This is a truly comprehensive, methodical tutorial for people like myself who are comfortable working with electronics, but are unknowledgeable about testing microwave ovens. I have the top-rated, gleaming stainless steel, above-the-range GE microwave that quit heating after only three years and four months of use. Because of your video, I easily identified a shorted HV transformer. (Prior to finding your video, I located two bad components: the HV diode and magnetron. However, the oven still didn't heat. A professional electrician tested the unit, failed to find the HV transformer failure and gave up.) The Malaysian-manufactured unit is stuffed with Southeast and Far East Asian components. In sharp contrast, our 22-year-old Ohio-manufactured Tappen 1000w microwave oven continues to give top performance and trouble-free service. (I would pay the premium and buy USA, if given the choice.) Thank you for producing an outstanding series of how-to videos, which are worthy of a college-level (or, at least, a good trade school) course in electronics.
I watch the previous video and what I have to say is that this video is fantastic and "electronicsNmore" know how to make good videos about microwaves. He is very detail and able to show how to test parts to people of any level of electricity knowledge. Congrats.
electronicsNmore - Thanks so much for sharing your expertise & posting this video. Using your helpful tests, I was able to rule out the magnatron, high voltage diode & transformer. The high voltage capacitor tested bad. Replaced it & my old 1982 Sharp R8320 convection microwave started right up. They don't make them dependable like that anymore. THANKS AGAIN!!
Very good videos about microwave fixing! Unfortunately my oven had a high voltage (5kv 0.7A) fuse blown which you didn't address in your videos (probably many ovens don't have one), but that was easy enough to figure out myself. My symptoms were: Everything else works but oven doesn't heat. Lights, fan, even transformer hum was present. After testing every other component I was suspecting some fault inside the magnetron even though it measured 0.3 ohm with an ESR meter. DMM showed below 0.1 ohm delta reading with leads shorted compared to connected to a magnetron so it was no help in my case. I fixed mine temporarily with a 0.315A 1000v FF multimeter fuse for the next 2-4 weeks until correct size fuses arrive from china (1.1€ for 5 pcs). I know that if the fuse blows now, the arc might not close inside the fuse because of inferior voltage rating and difference in construction. But I, a cheapass student, won't have a microwave otherwise so I take the risk of causing further problems with this cheap oven. :)
Great video. All of my components tested good but I saw sparks through the holes in my magnetron case. Knowing that couldn’t be good I replaced it and now it works. I had seen on another sight the same testing for the magnatron and they said it could test good but still have issues. I tore it apart afterwards to get the magnets and saw that the input inductor was burnt on the varnish. May be why it was sparking. But great video. I learned a lot.
your the best!!!...I just found out the problem of my whrpool microwave after watching your demonstrations...thanks a lot...your a good man not selfish, GOD BLESS YOU AND YOUR FAMILY....
I really enjoyed your video,Thank you very much. my Q is after i found the problem in my microwave was the rectifying diode,when in stall right one mic was working but take to long than normal heating.
Well, thank you for your videos. I tried to repair my Sanyo EM-V3405SW microwave (intermittent flickering appliance light when door was opened or during operation and pitch change in magnetron during flicker). I was able to trace it to a relay, which I replaced (confirmed that it was relay by shorting the high voltage side of relay. I ordered the relay, replaced it - microwave is running fine - but display is blank. Is there some video you have on testing LCD display operation ? I will admit, I had disconnected the front touch pad ribbon that goes into control panel, when I was testing relay operation. Problem is I have no schematic diagram of the control board and have no idea how the display gets lit.
Thanks for the video. I have tested all the switches, termal switches, fuse and all good. Everything is working except heating. There is no 120v on the entrance of the big transformer hence no charge on capacitor. What could be the issue?
Thank you Paul! Be sure to look over my extensive video playlists below for many other videos of interest to you, and most importantly take one minute to share a link to my channel with others on social networking sites. ua-cam.com/users/electronicsnmoreplaylists
Thank you so much! My metre doesn't go above 20M so can't do the second test on the diode, but it read 8.4 volts on the voltage test. I guess that is good enough eh? The Capacitor was the only faulty bit since the reading between the two terminals went to 1.4. No reading change on the terminals to casing. The microwave display and light comes on but as soon as I try to heat something, it instantly blows the fuse....would the bad capacitor do that? Great instructional, thanks again.
So helpful; thank you. If one of my capacitor caps (the plastic) snapped, is it OK to still use the capacitor, maybe with some electrical tape holding the broken plastic in place? tia.
Thanks for the video, it is the most informative guide I have seen so far. Excellent step by step instructions. I have one question. I am checking the step at 14:15 and instead of getting 95 ohm I got no measured value. Is there a way to further check the transformer? Thank you
No reading for the high voltage winding means a faulty transformer, or you failed to scrape away the clear coating on the transformer before touching the probe to the core.
Everything checked out okay on my microwave according to your guide on oven parts. But my 1st instinct was the Magnetron went bad but has 0.1 Ohm resistance which you said it is good (0.1 to 0.3 ohm). I put on heating and I can hear humming but no heat. Any suggestions? Thank you for your informative videos though.
Very likely if the diode and capacitor are both good. Sometimes a magnetron can test good, but be bad. Did you measure the resistance from each terminal on the magnetron to the metal chasis? You should not get any reading. If you do, it's bad. Use a high ohms range on your DMM. Thank You For Watching!
electronicsNmore I follow your guide and I didn't get any reading for touching metal chasis and one to the terminal. If I have another magnetron from other microwave can I hook it with the one that's not heating up to test?
If the size is similar(wattage), and it bolts in the exact same way, then yes. Substituting another known good one, will let you know if yours is faulty.
Glad you enjoyed the video! I have a lot of excellent videos on my channel that cover many different subjects, so be sure to check out my extensive video playlists for other videos of interest to you, rate thumbs up, and share my channel with others. Thank You
Most interesting, may I ask ? can you not measure the voltage out of the output transformer while on to see if the transformer is working ie sending power to the magnetron ? and what would you expect the resistance to be on those same leads with a the machine off and capacitors discharged?
VERY dangerous! You need a special HV probe like I made on my channel. Or you can remove it after unplugging the microwave and discharging the HV capacitor and do as shown below. Do as shown at your own risk. It's very dangerous for the average person. ua-cam.com/video/VicnLpnwO-k/v-deo.html
hey there, i have the analog electrical meter so could you pls tell me what position/symbol/mark to select to check the capacitor after you do the ohms check. ta
+Capricornarr If your meter is inexpensive and does not have a "F" setting meaning Farads(capacitance), then you are out of luck. You will have to rely on the resistance test.
+electronicsNmore Thanks for your quick response, I only have an analog electric meter which is clearly no good in this situation. Could you please suggest any good digital multi meter that would do all these jobs and I would be able to do all these checks? cheers mate.
Thanks so much for this tutorial and forum. Defy Convention Microwave oven DM0357. Just went dead. Perhaps overheated. I don't know. Keypad dead. Should I replace capacitor first, or the keypad? Or, is it possible the keypad alone needs replacing. Multimeter testing showed components are ok. Have to guess if capacitor must be replaced and/or keypad.
In my case it was the capacitor. Unfortunately it was the last thing I tested for I was afraid of the voltage thing. Anyway I did diode, magnetron, the little switches, those fuses and breakers first. One fo the 20A fuses was bad, replacing it bought the lights and display back, the microwave was turning but no heat. Anyway, when I finally get it off and check the capacitor, it was leaking oil and short. I just ordered one from Amazon and hopefully that's it. Thanks a lot! Will paypal some if the new caps fixes the issue.
Thanks for the videos. I've read your comments and I think I have a puzzle. The puzzle occurs when heating more than one batch that needs heating. The first batch heats fine. When we heat the second batch it takes longer. Everything else is fine. Please suggest any possible solutions. Thanks
Sounds like the magnetron is failing. You can try testing/replacing the capacitor/diode. You may also have an issue of burned relay contacts not allowing full current to the HV transformer.
I have watched your videos and they are helpful but I have a question. When testing the hi volt line on a GE transformer in our microwave, I get a reading of 76.5 on the high voltage side. Is that acceptable as you have mentioned 80-120 is desirable (you got 95.5). All of the other components have checked out as you mentioned and we did replace the diode but it still makes a loud humming noise and does not produce heat. The GE Profile Sensor convection microwave oven we have is 16 years old.
@@electronicsNmore well then the only thing left is to replace the magnetron because as you noted they can test correctly but still be defective. Your opinion?
Awesome video. Easy to follow steps. I have a GE countertop microwave that does not heat. Control panel functions fine. Fan runs. Light in oven comes on. Do not hear the sound of the magnetron kicking in. Followed your steps; i.e., door switches tested OK; relay on PCM registers 120VAC and then goes to zero when start is pressed. Magnetron checked Ok for ohms, however, the fins rattled when shaking the mag. Was able to push them together and eliminate the rattle. HV transformer, capacitor and diode all checked OK. I think it must be a faulty mag but is their any additional tests I can do before springing for a new mag?
If when testing the capacitor I got 1.9 ohms across the terminals. Does it mean that the capacitor is faulty. In reference with 4:06 to 4:25 of the video testing the capacitor.
Appreciate the videos, tremendous help. Lights would come on but microwave did not work. Replaced switch a d a thermocouple. Now everything works but exhaust fan turns on as sonn as I plug it in? I can switch speeds but won't turn off? Hope you can advise. Thank you in advance.
Hello, I have a dead microwave. The light works when you open the door, but no display nor do any buttons work, fuse is good. I have narrowed it down to the PC Transformer according to your very interesting and informative videos. How do you remove it from the board for testing? Thank you.
Awesome video, still have problems. Micro would buzz, but would not heat cup of water. Power setting button did not work, everything else did. Replaced Diode, set power to 2, fired it up, and fuse blew. Replaced fuse, turntable, fan etc. ran with transformer unhooked, all was O.K. until Transformer was connected, fuse blew again. All test readings on mag, transformer and cap are same as yours. Ideas? Also, can I wire a 20 amp household breaker in-line to test? Blowing ceramic fuses is getting expensive!.
This is an excellent guide for enthusiasts trying DIY fixing of microwave. One question: If high voltage transformer primary tests 120 v AC on each terminal to ground, what does that mean?
That means your transformer is not connected to the neutral wire allowing it to turn on. The circuit is not complete. You have to trace the wire and find out why(there may be a faulty switch or blown thermal cutoff). If you connect a 120V live / hot wire to one side of the transformer, and the other side(terminal) is not connected to the neutral wire, then you wire have 120V on each terminal. If the neutral is connected, you will have 120V on one side(power feeding in), and the other side connected to the neutral wire to complete the circuit, will be ZERO volts. Thanks For watching! Be sure to check out my video playlists.
Thanks for knowledgeful and helpful video. I need your assistance to resolve issue of burning fuse when microwave put in operation. checks on hv transformer, capacitor & diode found good. Resistance on PCB on L and N terminal found 1424 ohms which seems not normal. What may be cause please guide. Thanks
I only upload well explained/helpful videos and answer simple questions. I don't troubleshoot for viewers. I already spend way too much of my free time helping people, and get very little in return. This channel is underfunded. Watch my other microwave oven repair video below for more help. Thanks ua-cam.com/video/t1tdj3OnlXU/v-deo.html
For diode testing, why don’t you turn your multimeter dial to the diode test position? Hard to tell, but I believe it’s the 6:00 position on your meter.
this has been one of the best how to i have seen thanks for taking the time to share, is there a way to test the relays on the controlboard with out taking them off?
This is an excellent tutorial, very clear to understand. I have a related question: you indicate to use a 18k ohms 5-10w ceramic resistor to discharge the capacitor; may I use a film resistor of the same ratings? Thank you.
Great Video. How do I check when my turntable motor does not have 120V input power? I test the motor with 120V source and it works but there is no power supply to my motor.
I have 120V on the HV primary, the light comes on, the turnbtable rotates but no heat. HV transformer primary is 0.4 ohms, secondary winding is 90 ohms to ground, however, the HV secondary connector unplugged going to the magnetron is 0.3 ohms. Is that a secondary winding short? Do I need to replace the HV transformer?
Thanks for the proper, safe process. Interestingly, about half the folks DON'T test for shorts on the Mag (terminals to body) which ultimately was my issue as I was seeing continuity from terminal to body. Just received and install the new Mag and it tested out exactly as you specified .001-004 ohm across the terminals and OPEN from terminals to body and my unit is cooking again and operating quitely (comparatively speaking), it sounds like new again. I do have a few questions maybe you can answer as I haven't found anything yet on the subject: 1. can a shorted Mag be repaired? The terminal block looks clean, so it must be an internal short and 2. As far as the part # mine is an LG 2M246 050GF 1200watt and there is an additional set of letter/numbers under model #. Is the main number I need to worry about the 2M246 or are any of the other numbers important to match? Thanks again!
Thanks for the video, my Panasonic inverter microwave no longer working 2days ago. When I opened the door, the light came on then popped. The timer counts down, but no light, turn table not on, fan not on; Took out the 3 switches to test. Both prim and secondary closed when pressed... inter switch open when pressed... they look fine to me. The bulb actually burnt. wondering if u know the problem and what is next to test... Thanks in advance, Terry
Thanks for the reply. Are you referring to the pcb that contains the power relay? When I open the door, the lamp is supposed to be on. I checked the voltage between the lamp connectors and read 0 v. Between one connector and the chassis, it reads 110v. The other connector doesn't seem to get grounded. Is it possible that the Power Relay is busted? Any way to test that out?
Thanks for the useful video. My microwave display is not working (door + light is working and tested fuse is fine etc). I checked and the problem seems to be either with the small transformer on the display-board or the entire display board. For the small transformer(on the board), on the primary I got 125 ohms. And on the other side I get 1 ohm and 4 ohms (the video mentioned about 400 ohms for primary and 8-10 ohms on the secondary). Do I need to replace just the transformer or the entire display board. Thanks for your response.
First unplug the microwave. Next discharge the capacitor. After that, remove the blk/white wires connected to the primary side of the HV transformer coming from the larger relay on the PC board. Cover the terminals with electric tape. The purpose of doing that is to prevent the transformer/magnetron from powering up when you plug the unit back in to test the pc mounted transformer. CAREFULLY test the output voltages on the PC mounted transformer while the microwave is plugged in. Wear latex gloves to be safe. No need to press start on the oven. you should get around 12VAC on one set of pins, and around 6VAC on the other set of pine. All pins are on the same side of the transformer in a straight line. If you do not see that voltage, then the transformer is faulty if you see 120VAC between the two pins on the opposite side of the transformer. Thanks For watching. Be sure to share my channel and rate Thumbs Up.
Is it mandatory that I take one wire off the switch before I do the continuity test? Would i get wrong reading if i left both wires attached to the switch terminals?
Useful video thanks. I've done all the tests but for the diode (as I lack a resistor) and PCB transformer (which I assume to be ok as the display works). The microwave comes on and the display and light works etc, it just doesn't heat the food. I suspected the magnatron but it checks out ok according to your tests. As do the fuse, door switches and capacitor. The only discrepancy I have is the main transformer, the primary windings are at about 2 - 2.5 ohms between the terminals and the HV Power output lead about 160 ohms to the core. Do I have a transformer issue?
The diode can be tested w/o a resistor if you have a DMM that has a 50M or 60M range. How many watts is the microwave oven? You are positive the DMM is working properly?
I have a question if you can help me.I want to do an isolator transformer with 2 Microwave oven transformer the same.what I want to know as secondary shall I use the 2 red end between the 2 coil to connect bought transformer and disconnect the high voltage red and cut the wire touching the body.So I will have an input of 240v and an output 240v.What is the output of the 2 red wires between the coils?
+Joseph Cauchi Hi Joseph. You need to cut open the weld of a 220V MOT as shown in my other video, then remove the middle red wire(2-3 turns), along with the HV secondary. Take the primary from another MOT that is identical, and install it in the transformer that you removed the filament and HV winding from. You will end up with 220V in and 220V out.
I have a ge convection microwave. When I open the door the humming noise comes on and turn table turns is this the microwave shooting microwave at me or a fan running. microwave does warm my water in the cup. The only thing still under warranty is the magnetron should I throw microwave away or call repairman
Thanks a lot for your video. It helped me isolate the fault to what I think is the diode. This is a Kenmore Elite , about 6 years old. My problem is that I cannot find the diode it is using. It is marked CL04-12. I had to settle on buying from eBay and I bought three of them. When I replaced one of the new diodes in the microwave I still hear a loud hum. When I disconnect the magnetron the hum reduces substantially. Everything else is working, lights timer, turntable etc. The capacitor checks out at 1 microFarad. I suspect I got cheated on the diodes. The new diodes show 15 Mega Ohms in one direction and over limit in the other. I am using a Fluke 87v DMM. What else could be wrong? The magnetron also checks out as per the tests.
my multimeters already read 0.2-0.3 Ohms when the leads are touched together and I get the same reading when testing the magnetron and transformer secondary winding, so I don't know if one or the other is bad.
@@electronicsNmore I think my multimeters aren't accurate enough to read that low ohms, it was fluctuating between 0.2 and 0.3 ohms both while doing a reading or while just having the leads connected. I saw another video ua-cam.com/video/xJMorrJzm6c/v-deo.html which helped me confirm the transformer seems good. The capacitor and diode also seem ok, so I think it has to be the magnetron.
Great video. I was able to test all of my microwave's component and all have resistance reading like you mentioned. I did more tests, I used an energy meter to measure the wattage when in use. Plugged in, 2 watts. At power start, 38 watts (light, fan, turntable) When the magnetron kicks in, 400 watts. (Instead of 1200 W) Same, but with magnetron unplugged, 325 watts. (I think it's for the power transformer) I did buy a new capacitor & diode, but still doesn't work. Next step is to replace the magnetron. Any thoughts? Thanks very much. Carl
Can you hear a hum when the microwave turns on? Or does it run with the light on, fan on, and turn table only? If you swapped out the cap and diode, and you are getting 120V to the primary side of the transformer(DO NOT go anywhere near the HV red secondary wires!), then the magnetron is likely faulty even though it tests ok.
electronicsNmore Yes it does hum and there's power to the transformer. Just wanted to make sure it was the magnetron. A GE magnetron WB27X10305 is $250 - $280 in Canada. Thanks for your help.
Yes, it was an expensive model that matched the oven and GE doesn't make anymore. That's why I'm thinking of ordering it from here; www.appliancepartspros.com/ge-magnetron-wb27x10305-ap2026205.html By the time I add shipping, customs and currency exchange rate, It'll be about $160 Thanks, Carl
I'm trying to figure out the specs on a magnetron that is no longer available so I can replace it with a non-oem unit. The original is a Sanyo 2M219H which, from what I've read, is a 4.1kv rated unit (due to the "2M219" part, H being the physical size and layout of mounting ears, vents, etc). The problem is the tag on the oven itself says "microwave output" is 1000w which, if I'm not mistaken, would be equivalent to a 4.35kv rated magnetron. So I guess my question would be: can, would, or should the oven and the magnetron each have two different output ratings, or are they one in the same? Thanks for any info.
Hello, I have one (few yrs. old) Kenmore micro, and the fan, light, carousel runs continuously until I open door. Heating cycle does run and cycle fine with touch pad, and heating does go off when timer zeros out, the rest just continues to run until door is open or I unplug it. I have a feeling there is another relay on keyboard that is stuck in the closed position for the light, fan, and carousel cycle! It did this recently before but cleared up and now doing it again full time. Do you suppose this would be the be the case? I wouldn't be asking if weren't mounted under cabinet.. Old tired electrician...
HI have performed all of these checks and cannot find a problem but my convection / microwave still does not heat water. Everything sounds ok when the overis turned on. How can I check the voltage coming out of the transformer? I want to verify if the transformer is good / bad and maybe the magnatron is good / bad.
After unplugging the microwave, and discharging the capacitor, you can take the red high voltage wire leaving the transformer and position the terminal connector on the end of the wire VERY close to the transformer core(1 or 2 mm space), but not touching. Then plug in the microwave, and power it up for 3 seconds while standing back. You should hear and see arcing between the end of the wire and the transformer core if the output is working. When done testing, unplug the unit. More than likely a faulty magnetron.
Glad you enjoyed it! I have many videos on my channel that cover a wide range of subjects, so be sure to look over my video playlists below for other videos of interest to you, and most importantly share. Thank you ua-cam.com/users/electronicsnmoreplaylists
great video i have a combination of microwave and oven GE PT970S M2SS do you have any literature/information how to take the micro apart to see the components. I have no powers to the micro
+Antonio Pacheco Probably a blown fuse inside the microwave due to a faulty magnetron, capacitor, diode, or door switch. You need to take the time and do some research on your make/model microwave. Thanks
Thanks Joe! I have many excellent videos on this channel that cover many different topics, so be sure to look over my video playlists and most importantly share. Thank you
Diode voltage test confirmed good but ohm test at 20M (meter's highest setting) no reading in either direction. Does this confirm bad or should the test be done at 200M or higher to confirm bad?
I'm a fan! , but I have a puzzling problem, I have tested as you've instructed and I found a faulty high voltage diode and a faulty micro switch in the door (both parts were replaced), but the microwave continues not to heat. All other parts tested within normal range. the display panel works fine. I thought it maybe the magnatron as on testing I'm getting .5 ohms the other test is normal. Any help you can provide me would be great! or I will succumb to defeat and go out and buy another one (if only to get my wife to stop yelling at me to buy another)! Thank you!!!
Thanks for responding And yes the transformer is getting 120 volts so I will try a new magnatron and see if that resolves it and again thanks for the help!!!!
clean the contacts, and try shorting the 2 wires together on your meter to make sure it is working properly. You should get zero ohms when the test probes are shorted. Thanks For Watching! Be sure to rate Thumbs Up, and share my channel with others.
Great Work!! My GE microwave oven blew the internal 20A Fuse as it started to cook. Replaced fuse, set the time, hit the start cook and it ran for a second and the fuse blew again. Took it apart. Door switches seem ok. HV Cap seems ok. Read the right capacitance with my digital meter. HV Diode voltage test with 9 V battery passed but I don't get any voltage if I measure resistance in either direction! Shows open either direction. The magnetron resistance tests come out fine but if I shake it, it has a slight rattle noise! Checking the internal light of the microwave found the light bulb to not be seated tight. Any thoughts/comments what might be causing the 20A to blow? Thank
vj K Testing the diode with 9V is no good. You need much higher voltage as stated in the video, or a meter that has a very high ohm range of at least 50M. Use your car battery with the engine idling. The usual culprits are a faulty capacitor, diode, and lastly the magnetron. If you can rule out the capacitor and diode, then swap out the magnetron. Make sure the HV transformer passes the tests. Thanks For watching.
FYI is easy to follow ... My oven is not working ... I will follow this simple test only problem is I dont have a DVM... Maybe I can use 9volt battery connected to lamp as tester... Any good? Or there is a caution I needed to think like damaging a component? 😳😨🙏
Very good instructions. However, can I suggest you to add a test for the transformers low voltages ? You should test if there are no short between the secondaries.
Yes, the little ones. It could happen, sometimes, that because of a default on the board driving to a peak of current a hot point between the secondaries. This is valid not only for the microwaves. You can use the mutimeter to perform the test. In case of any doubt, you can drive direct current into each secondary with your external source and test the other secondary from its two ends and, 2nd test, one end of it to the two ends of the first one under DC. Repeat this with the second end of the secondary considered. In fact, it is an insulation test between those secondaries to perform.
Hi , I have a GE Microwave JVM6172SK1SS that I got free , only problem is the exhaust fan won't turn off. I changed the fan relays on the board but still won't turn off. I checked the door switches and the three temp sensors all ok . What else do you think I could test
@@electronicsNmore what would I check on the control board, what keeps the fan on untill it cools off enough to turn it back off. It must be stuck on. Thanks for your input. I don't care really want to replace the control board for they are over one hundred dollars, besides I like the challenge to try and find the faulty part on the control board.
I have a GE profile. The front control panel lights up, but will not take touch commands. I took apart and cleaned all ribbon contacts with contact cleaner, and still no good. New boards are too expensive. Any thoughts?
Hey. When I test the Diode one way, I get 50M. When I reverse the leads, it starts to count up to infinity. I have a 2000M setting on my meter. I purchased a new diode and I'm getting the same readings on the new one. Is it possible that the new one is faulty as well?
Most will rise up to the 300M range one direction, but I have seen others read to infinity. As long as one way is 30-55M and the other way is 300M to infinity, then you are OK.
Ok thanks for posting this video!! Question for ya, my GE microwave everything works but it does not heat and the turntable does not run! When it did this both stopped at the same time. Everything else sounds like it is running normal. What could cause both of these to go at the same time? Seems that they are not connected as far as what controls them or powers them. Even the display is still normal! PLEASE if you have any suggestions let me know! Excellent video just thought I would ask in your experience what could cause the two problems at the same time, so far I checked door switches and figuring out your instructions on checking the diode.
Sounds like a faulty door switch, OR when the door closes, contact is not being properly made to trigger a switch. Test each switch according to the video, and open/close the door while you test to ensure they are being triggered. POWER OFF!(unplugged)
I have an LG microwave that would start when I pressed the button, but would brown out and blow the breaker. Took the cover off, and the transformer was fried literally. Replaced the transformer, checked the capacitor, diode and magnetron, all checked out ok. Put it all back together, and it's still doing the same thing. Looks like it's trying to draw too much amperage on starting of the magnetron, then blows the breaker. Could it still be the capacitor even though it tests ok? thanks! Sean
You can try unplugging the microwave, discharging the capacitor as shown in my video, then unplugging the red HV wire from the transformer and leave it at least 1" away from any metal parts. CAREFULLY without touching ANYTHING inside the oven, stand back and plug in the microwave. Next, using the keypad, start up the microwave for a duration which would normally allow the problem to occur. If nothing happens, (everything works OK without heating), then you have a faulty capacitor, diode, magnetron, or you wired it wrong. Unplug the microwave when you finish the test. You do this at your own risk. Do it wrong, and touch anything while powered up, and you can be killed.
Microwave capacitors will usually have built-in resistors connected to each terminal so that the capacitor will discharge automatically when the oven is switched is not in use.
I'm using defy microwave DMO 351... It powers on but the timer doesn't display nothing, now when I set on the timer it goes 1 second then trips what might be the issue
Outstanding video. Very detailed. Thank you for your effort. I have a situation and could use your expertise. I have a Kenmore Elite over the range microwave. My Son heated up some grub late at night and my wife came in in the morning and heard the microwave humming and could not shut it off. she pulled the plug and plugged it back in and everything was fine except it would not heat and would make a weird noise when she would try to use it. I took it apart and found that the Magnatron cooling fan shroud was melted and would not let the fan turn (ie weird noise). I cut the shroud from around the fan; put it all back together (to see if everything worked before ordering new parts) and everything works fine except it doesn't heat. My conundrum is:Should I even try to repair this? The only reason I can think of that the microwave was running when she woke up is that the filter was so clogged (didn't even know that there was a filter and has been there for 6 years caked in grease) that the system couldn't cool itself; the shroud melted, stopping the fan, which was getting a signal to cool the Magnatron. Which put it in a loop (glitch). Wouldn't even be wasting your time; but this is a very expensive microwave to replace and it's too cool. :) .Everything on the inside looks brand new and is probably the thermal switch that tripped but wanted your expert opinion on this before I started. I guess I would like to know if you have heard of "anything" like this? My problems are "never" easy. Thank you in advance for any help. Mark
Mark Schneider You need to test the parts according to the video. Not much else I can suggest. I have 2 videos on this subject. If everything tests OK, then replacing the magnetron is usually a good idea even if it tests OK.
I have a Sharp microwave oven. Everything works except the digital display, including the clock of course. Any tips on the problem and how to fix it. Thanks in anticipation. I like this video. Very precise and clear.
My GE microwave is properly working except when it is done heating up the food, and we open the door, the fan is still blowing. So what is the possible recommendation that you can give? And one thing more, can you show me how to make a wire to discharge the capacitor? Thank you.
Sounds like a faulty door switch. You need to test them all very carefully, and open/close the door as you test them. Make the microwave is unplugged, and test according to the video. Good link here showing how to make the discharge tool. 1k to 10k is fine. www.ifixit.com/Guide/Constructing+a+Capacitor+Discharge+Tool/2177
Thank you, I did test the capacitor and it tests normal I think at 9.37 for a 10 ohm capacitor and the terminal to body on each test infinity (followed your video). The buzzing is coming from the transformer. If I unplug the magnatron the tranformer still hums but the loud buzzing stops. Left the magnatron unplugged disconnected HV wire to the capacitor normal hum from the transformer but no buzzing. The tests of the transformer were all normal low side read .7 at 200 ohms and terminal to body was infinate at 20M ohms. High side .5 at 200 ohms and terminal to body was infinate at 20M ohms. The HV wire tested 91.2 at 200 ohms. I also tested the new diode and it was normal. I tested all the door switches, the thermo sensor, the fuse and transformers on the board all were normal. Again everything works except buzzing from the transformer and no heat, the magnatron is silent. I visually again inspected the magnatron, no cracks, sounds, etc... I also retested it and get .5 at 200 ohms and each terminal to body reads infinate at 20M ohms. Do you still think it is the magnatron?? and again THANK YOU VERY MUCH FOR THE HELP!!!
If you unplugged the magnetron from the transformer, then got only a hum and no buzzing, then that would indicate the magnetron is causing the problem. You need to swap out the magnetron. (0.5 ohms) for the magnetron is higher than normal.
Hey Mike.... Great video! I'm looking for some advise before I can even think about trashing this older but expensive 1650 watt GE built-in oven. I get the annoying buzzing BUT the oven does still heat at what seems to be it's normal heat rate. Here is what I did so far..... 1.I did ALL the magnetron tests in your video. All tests were normal EXCEPT when testing across the 2 terminal plug on a 250 ohm setting, I get a reading of point five (.5) This is also the exact same reading I get when I simply touch only the 2 probes together. Does this indicate that there is a short since .5 is my starting resistance due to the resistance of the meter and probes itself? IF yes, I do not see how the oven would still be warming! I also tried 2 other cheaper meters and each said resistance was one point zero. (1.0) Again, both meters tested at 1.0 when only touching the probes together. (Again I assume this is because of the normal resistance to the meter wire and probe itself and the meter just not being 100 percent calculated) Do you think I have a full short in the mag based on the above reading? 2. Next, I ran ALL of your TRANSFORMER test. All were ok EXCEPT on the high power wire test I got a reading of 79.5 olm on my good meter and 80 and 79.5 on the other two cheapo meters that I have. I believe that you said between 80 and 140 or so was most common I am at the extreme low end or below....so could that be causing my BUZZZZ? 3. I also tested the cap and diode test. Both test were good. (did a test using a 9v battery for the diode) Both of those test we ok as I expected. 4. I removed the mag. Shook it. No noise. I also carefully looked for cracks and any burning on the head. The silver thingee that surrounds the head of the mag was nice and shiny silver but there is some kind of metal thing inside of that shiny silver part that was black.... but i assume that is normal....right? 5. I can not tell if the buzzz sound comes from the mag or transformer. I disconnected the 2-wire terminal plug that goes into the rear of the mag. When I turned the oven on, i did not hear any buzzing, but of course there was no heat :) I would guess that might not tell me anything since I assume that pulling out the mag might also stop the buzzing even if the transformer was bad and causing the mag to buzzz. Any thoughts or questions would be really appreciated Thanks!
+MrUsaer Hi there. I'm Doug. :-) 80 ohms on the HV secondary is fine. You can unplug the unit, discharge the capacitor, then unplug the red HV wire from the transformer leading to the capacitor and leave it sticking out and away from the metal chassis. Plug in the oven, stand away from the open areas(danger areas) of the oven, and TOUCH NOTHING except for the control pad. Enter 10 seconds and press start. See if the buzzing sound is gone while the oven is running, if it is, then you likely have a faulty magnetron even though it tests ok. Unplug the oven, discharge the cap again to be safe, then you can touch things.
I will have to watch the video again. Based on watching and replaying sections, I think my problem is the capacitor or the diode. I have a Sharp R-4A77 and it has 3 microswitches to the door. The instant I try to heat, it blows the fuse but the clock display is fine until I try to heat (I'll remove the good fuse shortly). I checked the operation of the 3 door micro switches with wiring pretty much removed (removed from wire harness), 2 NO and 1 NC, and they appear to function appropriately. What I find odd is the 1 NC when back in the wire harness has continuity when the microwave door is open or closed, but again, operates appropriately when removed from the wire harness. Sound plausible to you? So I believe you indicate if I am blowing fuses, it is likely the diode or the capacitor, correct? I am a bit leery on testing those but perhaps I will gain more confidence if I get the resistor you mention to discharge the capacitor. I would appreciate your thoughts as I hate to send the microwave to the land fill if repairable.
Hey elec my microwave packed in yesterday. Ive done all the testing that you said. It runs like all is well but does not get hot at all. everything tests good the magnetron is good and the capacitor is good i changed the diode still nothing. However i do get 2.5 ohms on my primary windings of the transformer any idea do you think that transformer is the problem the HV wires are fine to what you said and none of the wires short to the casing? Thanks man hope to get it working got no cash for a new one:) i get the tell tale hummmm from the transformer and all but nothing.
electronicsNmore thanks elec the diode is brand new so that should be good. i do struggle to test cap though as i only have 2m ohm on my meter. if i test across the terminals i get it count past 2m ohms not sure if that means the 10m ohm resister is good in the cap or not. the magnetron tests good but i guess there could be something wrong with it. anyway thank you so much elec solid video man keep it up.
My HG m-wave runs & hums, and does the deep hum as if it's heating. I tested the major components and they all passed, except possibly the HV diode between the capacitor & chassis. It passed the tests except the last ohm tests without the battery, it didn't change readings for that. It looks & sounds like it's running fine, just doesn't heat. Any ideas?
Usually the diode, capacitor or magnetron last. The magnetron can test OK, but still be faulty. You have to be absolutely sure the diode and capacitor are good before swapping out the mag.
Hello, I have a GE microwave and it once blown up the noise filter fuse. I replaced it and it blew again. So the next possible test is door switches and that was the problem. I ordered the switches online and changed them too but this time my breaker went off. Did I miss anything here? Also my switches looks good as per your test videos. When ever the door opens the fuse blow. Can you help me pls.
Hi My meter reads 1 at 200 ohms open circuit (not 0.L like yours) and 0.7 closed circuit. I have checked the magnetron and it shows 0.7 ohms across the terminals directly from the meter with no jumper wires. When I use 2000k ohms to terminal and body it continues to read 1. Does this mean that it is faulty?
Your meter is not calibrated. When you touch the probes together you should have ZERO ohms. I think your due for a new meter if you cannot open and calibrate it. If you set the DMM at 2000k and you notice no change in the reading from each terminal on the mag to ground, then your OK. Understand this test is not 100%. If everything else tests OK according to the video, then usually the magnetron is faulty. Buy a new meter and repeat the tests. All the info you need is in the video, as well as in all the comments below. Thanks For Watching
Hey Doug.... No buzzing after following your instructions below. I am going to buy a new magnetron and hope for the best. I was curious about 2 things....... 1, When I followed your instructions by disconnecting the red HV from the transformer, would the mag be getting power from the other wire going from the capacitor to the mag? 2. Would you expect that low-end 80 ohm reading that I have on the HV secondary to gradually get lower as the oven gets older and result in less effective heating for cooking? I will post back the outcome once i receive the new mag from online purchase and plug her in. Thank you very much for your help!!!
+electronicsNmore Yes, pretty sure. I did the cap tests per your video and did the 9v battery test for the diode....which I believe I read later that you were not a fan of.... anyway, the diode test showed full 9.3 volts one way and about 6 volts the other way as best I recall. If the mag ordered online does not work I am allowed to return to the seller. So not a big deal if it turns out to be something else. Should have it by Friday or Monday..... Will let you know... Thanks again!
Thanks for uploading this was so helpful! While testing the transformer, the resistance between the single high voltage wire and the body of the core did not change the reading from OL. Does this mean the transformer is broken?
Place the digital meter on a low ohms range(up to 200 ohms or 1k ohm) You should get a reading. Be sure to scrape the transformer core in the area you test from. There is an enamel coating which must be removed to expose bare metal prior to testing. Thanks for watching. Be sure to rate Thumbs Up, and share my channel with others.
Wavetek 27xt, but I also use another very good DMM which I made a product review video for. The DMM is a Mustool. Please refer to my "Product Review" video playlist. Thanks
This is a truly comprehensive, methodical tutorial for people like myself who are comfortable working with electronics, but are unknowledgeable about testing microwave ovens. I have the top-rated, gleaming stainless steel, above-the-range GE microwave that quit heating after only three years and four months of use. Because of your video, I easily identified a shorted HV transformer.
(Prior to finding your video, I located two bad components: the HV diode and magnetron. However, the oven still didn't heat. A professional electrician tested the unit, failed to find the HV transformer failure and gave up.)
The Malaysian-manufactured unit is stuffed with Southeast and Far East Asian components. In sharp contrast, our 22-year-old Ohio-manufactured Tappen 1000w microwave oven continues to give top performance and trouble-free service. (I would pay the premium and buy USA, if given the choice.)
Thank you for producing an outstanding series of how-to videos, which are worthy of a college-level (or, at least, a good trade school) course in electronics.
Glad my video was able to help you!
I watch the previous video and what I have to say is that this video is fantastic and "electronicsNmore" know how to make good videos about microwaves. He is very detail and able to show how to test parts to people of any level of electricity knowledge. Congrats.
Agree with the fact that he is accurate enough, but not too wordy to confuse anybody. Very good videos indeed.
electronicsNmore - Thanks so much for sharing your expertise & posting this video. Using your helpful tests, I was able to rule out the magnatron, high voltage diode & transformer. The high voltage capacitor tested bad. Replaced it & my old 1982 Sharp R8320 convection microwave started right up. They don't make them dependable like that anymore. THANKS AGAIN!!
Very good videos about microwave fixing! Unfortunately my oven had a high voltage (5kv 0.7A) fuse blown which you didn't address in your videos (probably many ovens don't have one), but that was easy enough to figure out myself.
My symptoms were: Everything else works but oven doesn't heat. Lights, fan, even transformer hum was present.
After testing every other component I was suspecting some fault inside the magnetron even though it measured 0.3 ohm with an ESR meter. DMM showed below 0.1 ohm delta reading with leads shorted compared to connected to a magnetron so it was no help in my case.
I fixed mine temporarily with a 0.315A 1000v FF multimeter fuse for the next 2-4 weeks until correct size fuses arrive from china (1.1€ for 5 pcs).
I know that if the fuse blows now, the arc might not close inside the fuse because of inferior voltage rating and difference in construction. But I, a cheapass student, won't have a microwave otherwise so I take the risk of causing further problems with this cheap oven. :)
Great video. All of my components tested good but I saw sparks through the holes in my magnetron case. Knowing that couldn’t be good I replaced it and now it works. I had seen on another sight the same testing for the magnatron and they said it could test good but still have issues. I tore it apart afterwards to get the magnets and saw that the input inductor was burnt on the varnish. May be why it was sparking. But great video. I learned a lot.
your the best!!!...I just found out the problem of my whrpool microwave after watching your demonstrations...thanks a lot...your a good man not selfish, GOD BLESS YOU AND YOUR FAMILY....
Thank you! Be sure to share my channel with others and rate thumbs up.
I really enjoyed your video,Thank you very much.
my Q is after i found the problem in my microwave was the rectifying diode,when in stall right one mic was working but take to long than normal heating.
This is the simplest instruction for us amateur fixers in my humble op.
this is the best teaching video, it is the best of all and wil be the best forever.
Thank you! :-) Please be sure to share my channel, watch my other videos, and subscribe.
Well, thank you for your videos. I tried to repair my Sanyo EM-V3405SW microwave (intermittent flickering appliance light when door was opened or during operation and pitch change in magnetron during flicker).
I was able to trace it to a relay, which I replaced (confirmed that it was relay by shorting the high voltage side of relay.
I ordered the relay, replaced it - microwave is running fine - but display is blank. Is there some video you have on testing LCD display operation ?
I will admit, I had disconnected the front touch pad ribbon that goes into control panel, when I was testing relay operation. Problem is I have no schematic diagram of the control board and have no idea how the display gets lit.
Thanks for the video.
I have tested all the switches, termal switches, fuse and all good. Everything is working except heating. There is no 120v on the entrance of the big transformer hence no charge on capacitor. What could be the issue?
Excellent explanation of each test. You must be very good at what you do.
Thank you Paul! Be sure to look over my extensive video playlists below for many other videos of interest to you, and most importantly take one minute to share a link to my channel with others on social networking sites.
ua-cam.com/users/electronicsnmoreplaylists
Your attention to detail is awesome, except my name is Raul , not Paul. Hahahahahaha. Its ok, i get that all the time
@@raiderman28 LOL. Sorry about that.
Thank you so much! My metre doesn't go above 20M so can't do the second test on the diode, but it read 8.4 volts on the voltage test. I guess that is good enough eh? The Capacitor was the only faulty bit since the reading between the two terminals went to 1.4. No reading change on the terminals to casing.
The microwave display and light comes on but as soon as I try to heat something, it instantly blows the fuse....would the bad capacitor do that? Great instructional, thanks again.
So helpful; thank you. If one of my capacitor caps (the plastic) snapped, is it OK to still use the capacitor, maybe with some electrical tape holding the broken plastic in place? tia.
Great videos! If I have parts that are bad. Where do you get said parts?
Other units, or?
Thanks for the video, it is the most informative guide I have seen so far. Excellent step by step instructions. I have one question. I am checking the step at 14:15 and instead of getting 95 ohm I got no measured value. Is there a way to further check the transformer? Thank you
No reading for the high voltage winding means a faulty transformer, or you failed to scrape away the clear coating on the transformer before touching the probe to the core.
Everything checked out okay on my microwave according to your guide on oven parts. But my 1st instinct was the Magnetron went bad but has 0.1 Ohm resistance which you said it is good (0.1 to 0.3 ohm). I put on heating and I can hear humming but no heat. Any suggestions? Thank you for your informative videos though.
Very likely if the diode and capacitor are both good. Sometimes a magnetron can test good, but be bad. Did you measure the resistance from each terminal on the magnetron to the metal chasis? You should not get any reading. If you do, it's bad. Use a high ohms range on your DMM.
Thank You For Watching!
electronicsNmore I follow your guide and I didn't get any reading for touching metal chasis and one to the terminal. If I have another magnetron from other microwave can I hook it with the one that's not heating up to test?
If the size is similar(wattage), and it bolts in the exact same way, then yes. Substituting another known good one, will let you know if yours is faulty.
Magnetron doesn't have any wattage on the label. How can you tell the wattage?
Go by the label on the microwave oven. 900w /1000w...etc.
Hi how do you check the thermal switches when you removes the wires sould you have resistance or should they be open when good?
Thank your for taking the time to make this troubleshooting video, it was helpful!
Glad you enjoyed the video! I have a lot of excellent videos on my channel that cover many different subjects, so be sure to check out my extensive video playlists for other videos of interest to you, rate thumbs up, and share my channel with others. Thank You
Most interesting, may I ask ? can you not measure the voltage out of the output transformer while on to see if the transformer is working ie sending power to the magnetron ? and what would you expect the resistance to be on those same leads with a the machine off and capacitors discharged?
VERY dangerous! You need a special HV probe like I made on my channel. Or you can remove it after unplugging the microwave and discharging the HV capacitor and do as shown below. Do as shown at your own risk. It's very dangerous for the average person.
ua-cam.com/video/VicnLpnwO-k/v-deo.html
Do you have to start the vehicle first,or after to make your connections? To test the oven diode.
Thanks for very valued information about micro oven trouble shooting ,
Excellent video, Thank you for the detailed step by step instructions and component test info! ...I will definitely share the link with others !
hey there, i have the analog electrical meter so could you pls tell me what position/symbol/mark to select to check the capacitor after you do the ohms check. ta
+Capricornarr
If your meter is inexpensive and does not have a "F" setting meaning Farads(capacitance), then you are out of luck. You will have to rely on the resistance test.
+electronicsNmore Thanks for your quick response, I only have an analog electric meter which is clearly no good in this situation. Could you please suggest any good digital multi meter that would do all these jobs and I would be able to do all these checks? cheers mate.
Vichy VC99 on Ebay.
It turned out to be the door switch. There are two switches in series. The mount on one swtich was broken so the switch shorted. Thx for your help.
It was the magnatron. Installed a new one and it works great. Thank you very much for the great videos and the help!!!!!!
Good to hear! Share and rate Thumbs Up. Thanks.
Thanks so much for this tutorial and forum. Defy Convention Microwave oven DM0357. Just went dead. Perhaps overheated. I don't know. Keypad dead. Should I replace capacitor first, or the keypad? Or, is it possible the keypad alone needs replacing. Multimeter testing showed components are ok. Have to guess if capacitor must be replaced and/or keypad.
In my case it was the capacitor. Unfortunately it was the last thing I tested for I was afraid of the voltage thing. Anyway I did diode, magnetron, the little switches, those fuses and breakers first. One fo the 20A fuses was bad, replacing it bought the lights and display back, the microwave was turning but no heat. Anyway, when I finally get it off and check the capacitor, it was leaking oil and short. I just ordered one from Amazon and hopefully that's it. Thanks a lot! Will paypal some if the new caps fixes the issue.
Thanks for the videos.
I've read your comments and I think I have a puzzle.
The puzzle occurs when heating more than one batch that needs heating. The first batch heats fine. When we heat the second batch it takes longer. Everything else is fine. Please suggest any possible solutions. Thanks
Sounds like the magnetron is failing. You can try testing/replacing the capacitor/diode. You may also have an issue of burned relay contacts not allowing full current to the HV transformer.
Can the PCB transformer test be done while still attached to the board? Or do I need to de-solder the transformer?
Great great videos! I'm reviewing at work and can't wait to go home and fix my KitchenAid microwave!
Good luck. Hope you fix it. :-)
I have watched your videos and they are helpful but I have a question. When testing the hi volt line on a GE transformer in our microwave, I get a reading of 76.5 on the high voltage side. Is that acceptable as you have mentioned 80-120 is desirable (you got 95.5). All of the other components have checked out as you mentioned and we did replace the diode but it still makes a loud humming noise and does not produce heat. The GE Profile Sensor convection microwave oven we have is 16 years old.
That's fine.
@@electronicsNmore well then the only thing left is to replace the magnetron because as you noted they can test correctly but still be defective. Your opinion?
Awesome video. Easy to follow steps. I have a GE countertop microwave that does not heat. Control panel functions fine. Fan runs. Light in oven comes on. Do not hear the sound of the magnetron kicking in. Followed your steps; i.e., door switches tested OK; relay on PCM registers 120VAC and then goes to zero when start is pressed. Magnetron checked Ok for ohms, however, the fins rattled when shaking the mag. Was able to push them together and eliminate the rattle. HV transformer, capacitor and diode all checked OK. I think it must be a faulty mag but is their any additional tests I can do before springing for a new mag?
THIS IS BRILLIANT. EVEN THE THICKEST CAN FOLLOW THE DEMONSTRATION
TWO THUMBS UP 22-9 2015
+Michael Loftus Thank You! Be sure to watch my other microwave oven repair video as well.
If when testing the capacitor I got 1.9 ohms across the terminals. Does it mean that the capacitor is faulty. In reference with 4:06 to 4:25 of the video testing the capacitor.
You have a shorted capacitor. :-)
Appreciate the videos, tremendous help. Lights would come on but microwave did not work. Replaced switch a d a thermocouple. Now everything works but exhaust fan turns on as sonn as I plug it in? I can switch speeds but won't turn off? Hope you can advise. Thank you in advance.
Bad thermostat(heat sensor). Make sure you installed the correct parts, and wired them correctly.
Hello,
I have a dead microwave. The light works when you open the door, but no display nor do any buttons work, fuse is good. I have narrowed it down to the PC Transformer according to your very interesting and informative videos. How do you remove it from the board for testing? Thank you.
Awesome video, still have problems. Micro would buzz, but would not heat cup of water. Power setting button did not work, everything else did. Replaced Diode, set power to 2, fired it up, and fuse blew. Replaced fuse, turntable, fan etc. ran with transformer unhooked, all was O.K. until Transformer was connected, fuse blew again. All test readings on mag, transformer and cap are same as yours. Ideas? Also, can I wire a 20 amp household breaker in-line to test? Blowing ceramic fuses is getting expensive!.
Fuse usually blows if a door switch is misaligned or faulty, the cap is faulty, or the magnetron is shorted. Thanks for watching!
This is an excellent guide for enthusiasts trying DIY fixing of microwave.
One question:
If high voltage transformer primary tests 120 v AC on each terminal to ground, what does that mean?
That means your transformer is not connected to the neutral wire allowing it to turn on. The circuit is not complete. You have to trace the wire and find out why(there may be a faulty switch or blown thermal cutoff). If you connect a 120V live / hot wire to one side of the transformer, and the other side(terminal) is not connected to the neutral wire, then you wire have 120V on each terminal. If the neutral is connected, you will have 120V on one side(power feeding in), and the other side connected to the neutral wire to complete the circuit, will be ZERO volts.
Thanks For watching! Be sure to check out my video playlists.
Thanks for knowledgeful and helpful video. I need your assistance to resolve issue of burning fuse when microwave put in operation. checks on hv transformer, capacitor & diode found good.
Resistance on PCB on L and N terminal found 1424 ohms which seems not normal. What may be cause please guide. Thanks
I only upload well explained/helpful videos and answer simple questions. I don't troubleshoot for viewers. I already spend way too much of my free time helping people, and get very little in return. This channel is underfunded. Watch my other microwave oven repair video below for more help. Thanks
ua-cam.com/video/t1tdj3OnlXU/v-deo.html
For diode testing, why don’t you turn your multimeter dial to the diode test position? Hard to tell, but I believe it’s the 6:00 position on your meter.
this has been one of the best how to i have seen thanks for taking the time to share, is there a way to test the relays on the controlboard with out taking them off?
InstaBlaster...
This is an excellent tutorial, very clear to understand. I have a related question: you indicate to use a 18k ohms 5-10w ceramic resistor to discharge the capacitor; may I use a film resistor of the same ratings? Thank you.
Any resistor, just as long as the wattage/resistance value is close.
Great Video. How do I check when my turntable motor does not have 120V input power? I test the motor with 120V source and it works but there is no power supply to my motor.
Trace the wires. Could be a faulty relay.
Hi , you could also test the diode with a 9 volt battery since our multimeter tester cannot supply enough power to elicit a reading
For a reliable test, higher voltage is best.
I have 120V on the HV primary, the light comes on, the turnbtable rotates but no heat. HV transformer primary is 0.4 ohms, secondary winding is 90 ohms to ground, however, the HV secondary connector unplugged going to the magnetron is 0.3 ohms. Is that a secondary winding short? Do I need to replace the HV transformer?
Once again, a really fantastic video. My only query is why don't you just test the diode with your meter ?
You can't test high voltage diodes using the diode test setting on a DMM. Thanks for watching!
Respectfully appreciate you for the information
Thanks for the proper, safe process. Interestingly, about half the folks DON'T test for shorts on the Mag (terminals to body) which ultimately was my issue as I was seeing continuity from terminal to body. Just received and install the new Mag and it tested out exactly as you specified .001-004 ohm across the terminals and OPEN from terminals to body and my unit is cooking again and operating quitely (comparatively speaking), it sounds like new again. I do have a few questions maybe you can answer as I haven't found anything yet on the subject: 1. can a shorted Mag be repaired? The terminal block looks clean, so it must be an internal short and 2. As far as the part # mine is an LG 2M246 050GF 1200watt and there is an additional set of letter/numbers under model #. Is the main number I need to worry about the 2M246 or are any of the other numbers important to match? Thanks again!
Not worth the time repairing, you can buy a used replacement on Ebay at a low cost. Thanks for watching! Be sure to share my channel with others.
@@electronicsNmore Will do! KUTGW!
Thanks for the video, my Panasonic inverter microwave no longer working 2days ago. When I opened the door, the light came on then popped. The timer counts down, but no light, turn table not on, fan not on; Took out the 3 switches to test. Both prim and secondary closed when pressed... inter switch open when pressed... they look fine to me. The bulb actually burnt. wondering if u know the problem and what is next to test... Thanks in advance, Terry
Hi there. Sounds like you may need to swap out the power board.
Thanks for the reply. Are you referring to the pcb that contains the power relay?
When I open the door, the lamp is supposed to be on. I checked the voltage between the lamp connectors and read 0 v. Between one connector and the chassis, it reads 110v. The other connector doesn't seem to get grounded. Is it possible that the Power Relay is busted? Any way to test that out?
Thanks for the useful video. My microwave display is not working (door + light is working and tested fuse is fine etc). I checked and the problem seems to be either with the small transformer on the display-board or the entire display board. For the small transformer(on the board), on the primary I got 125 ohms. And on the other side I get 1 ohm and 4 ohms (the video mentioned about 400 ohms for primary and 8-10 ohms on the secondary). Do I need to replace just the transformer or the entire display board. Thanks for your response.
First unplug the microwave. Next discharge the capacitor. After that, remove the blk/white wires connected to the primary side of the HV transformer coming from the larger relay on the PC board. Cover the terminals with electric tape. The purpose of doing that is to prevent the transformer/magnetron from powering up when you plug the unit back in to test the pc mounted transformer. CAREFULLY test the output voltages on the PC mounted transformer while the microwave is plugged in. Wear latex gloves to be safe. No need to press start on the oven. you should get around 12VAC on one set of pins, and around 6VAC on the other set of pine. All pins are on the same side of the transformer in a straight line. If you do not see that voltage, then the transformer is faulty if you see 120VAC between the two pins on the opposite side of the transformer.
Thanks For watching. Be sure to share my channel and rate Thumbs Up.
Is it mandatory that I take one wire off the switch before I do the continuity test? Would i get wrong reading if i left both wires attached to the switch terminals?
Removing one wire ensures reliable testing.
Useful video thanks.
I've done all the tests but for the diode (as I lack a resistor) and PCB transformer (which I assume to be ok as the display works). The microwave comes on and the display and light works etc, it just doesn't heat the food. I suspected the magnatron but it checks out ok according to your tests. As do the fuse, door switches and capacitor. The only discrepancy I have is the main transformer, the primary windings are at about 2 - 2.5 ohms between the terminals and the HV Power output lead about 160 ohms to the core.
Do I have a transformer issue?
The diode can be tested w/o a resistor if you have a DMM that has a 50M or 60M range. How many watts is the microwave oven? You are positive the DMM is working properly?
Such a good video, helped me fix my microwave
I have a question if you can help me.I want to do an isolator transformer with 2 Microwave oven transformer the same.what I want to know as secondary shall I use the 2 red end between the 2 coil to connect bought transformer and disconnect the high voltage red and cut the wire touching the body.So I will have an input of 240v and an output 240v.What is the output of the 2 red wires between the coils?
+Joseph Cauchi
Hi Joseph. You need to cut open the weld of a 220V MOT as shown in my other video, then remove the middle red wire(2-3 turns), along with the HV secondary. Take the primary from another MOT that is identical, and install it in the transformer that you removed the filament and HV winding from. You will end up with 220V in and 220V out.
Thank you I will do it like you have advised.
I have a ge convection microwave. When I open the door the humming noise comes on and turn table turns is this the microwave shooting microwave at me or a fan running. microwave does warm my water in the cup. The only thing still under warranty is the magnetron should I throw microwave away or call repairman
My LG I Wave the problem the display is not changed only the last digit is light on, I need advise to trouble shoot if possible to use again.
Thanks a lot for your video. It helped me isolate the fault to what I think is the diode. This is a Kenmore Elite , about 6 years old. My problem is that I cannot find the diode it is using. It is marked CL04-12. I had to settle on buying from eBay and I bought three of them. When I replaced one of the new diodes in the microwave I still hear a loud hum.
When I disconnect the magnetron the hum reduces substantially. Everything else is working, lights timer, turntable etc. The capacitor checks out at 1 microFarad.
I suspect I got cheated on the diodes.
The new diodes show 15 Mega Ohms in one direction and over limit in the other. I am using a Fluke 87v DMM.
What else could be wrong? The magnetron also checks out as per the tests.
my multimeters already read 0.2-0.3 Ohms when the leads are touched together and I get the same reading when testing the magnetron and transformer secondary winding, so I don't know if one or the other is bad.
Deduct the reading from the measurement you take.
@@electronicsNmore I think my multimeters aren't accurate enough to read that low ohms, it was fluctuating between 0.2 and 0.3 ohms both while doing a reading or while just having the leads connected. I saw another video ua-cam.com/video/xJMorrJzm6c/v-deo.html which helped me confirm the transformer seems good. The capacitor and diode also seem ok, so I think it has to be the magnetron.
what if the rsistance of the primary of the transformer reads 2.5 ohms? is that good or bad?
Great video. I was able to test all of my microwave's component and all have resistance reading like you mentioned. I did more tests, I used an energy meter to measure the wattage when in use.
Plugged in, 2 watts.
At power start, 38 watts (light, fan, turntable)
When the magnetron kicks in, 400 watts. (Instead of 1200 W)
Same, but with magnetron unplugged, 325 watts. (I think it's for the power transformer)
I did buy a new capacitor & diode, but still doesn't work.
Next step is to replace the magnetron.
Any thoughts?
Thanks very much.
Carl
Can you hear a hum when the microwave turns on? Or does it run with the light on, fan on, and turn table only? If you swapped out the cap and diode, and you are getting 120V to the primary side of the transformer(DO NOT go anywhere near the HV red secondary wires!), then the magnetron is likely faulty even though it tests ok.
electronicsNmore Yes it does hum and there's power to the transformer.
Just wanted to make sure it was the magnetron.
A GE magnetron WB27X10305 is $250 - $280 in Canada.
Thanks for your help.
WOW. What a rip off. I have 2 laying around my house. Cheaper to buy a new microwave.
Yes, it was an expensive model that matched the oven and GE doesn't make anymore. That's why I'm thinking of ordering it from here;
www.appliancepartspros.com/ge-magnetron-wb27x10305-ap2026205.html
By the time I add shipping, customs and currency exchange rate, It'll be about $160
Thanks,
Carl
I'm trying to figure out the specs on a magnetron that is no longer available so I can replace it with a non-oem unit. The original is a Sanyo 2M219H which, from what I've read, is a 4.1kv rated unit (due to the "2M219" part, H being the physical size and layout of mounting ears, vents, etc).
The problem is the tag on the oven itself says "microwave output" is 1000w which, if I'm not mistaken, would be equivalent to a 4.35kv rated magnetron. So I guess my question would be: can, would, or should the oven and the magnetron each have two different output ratings, or are they one in the same?
Thanks for any info.
Hello,
I have one (few yrs. old) Kenmore micro, and the fan, light, carousel runs continuously until I open door. Heating cycle does run and cycle fine with touch pad, and heating does go off when timer zeros out, the rest just continues to run until door is open or I unplug it. I have a feeling there is another relay on keyboard that is stuck in the closed position for the light, fan, and carousel cycle! It did this recently before but cleared up and now doing it again full time. Do you suppose this would be the be the case?
I wouldn't be asking if weren't mounted under cabinet..
Old tired electrician...
HI have performed all of these checks and cannot find a problem but my convection / microwave still does not heat water. Everything sounds ok when the overis turned on. How can I check the voltage coming out of the transformer? I want to verify if the transformer is good / bad and maybe the magnatron is good / bad.
After unplugging the microwave, and discharging the capacitor, you can take the red high voltage wire leaving the transformer and position the terminal connector on the end of the wire VERY close to the transformer core(1 or 2 mm space), but not touching. Then plug in the microwave, and power it up for 3 seconds while standing back. You should hear and see arcing between the end of the wire and the transformer core if the output is working. When done testing, unplug the unit. More than likely a faulty magnetron.
I thank you for this information . I find it absolutely well prepared and very informative .
Glad you enjoyed it! I have many videos on my channel that cover a wide range of subjects, so be sure to look over my video playlists below for other videos of interest to you, and most importantly share. Thank you
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great video i have a combination of microwave and oven GE PT970S M2SS do you have any literature/information how to take the micro apart to see the components. I have no powers to the micro
+Antonio Pacheco
Probably a blown fuse inside the microwave due to a faulty magnetron, capacitor, diode, or door switch. You need to take the time and do some research on your make/model microwave.
Thanks
Excellent video. Very in depth and detailed
Thanks Joe! I have many excellent videos on this channel that cover many different topics, so be sure to look over my video playlists and most importantly share. Thank you
Diode voltage test confirmed good but ohm test at 20M (meter's highest setting) no reading in either direction. Does this confirm bad or should the test be done at 200M or higher to confirm bad?
Not high enough range to properly test.
I'm a fan! , but I have a puzzling problem, I have tested as you've instructed and I found a faulty high voltage diode and a faulty micro switch in the door (both parts were replaced), but the microwave continues not to heat. All other parts tested within normal range. the display panel works fine. I thought it maybe the magnatron as on testing I'm getting .5 ohms the other test is normal. Any help you can provide me would be great! or I will succumb to defeat and go out and buy another one (if only to get my wife to stop yelling at me to buy another)! Thank you!!!
If the large transformer is being supplied 120V on the primary side from the circuit board relay, then I'd say the magnetron is bad.
Thanks for responding And yes the transformer is getting 120 volts so I will try a new magnatron and see if that resolves it and again thanks for the help!!!!
my hv transformer is reading 4ohms instead of the less than 1ohm you mention. your thoughts?
clean the contacts, and try shorting the 2 wires together on your meter to make sure it is working properly. You should get zero ohms when the test probes are shorted.
Thanks For Watching! Be sure to rate Thumbs Up, and share my channel with others.
Great Work!!
My GE microwave oven blew the internal 20A Fuse as it started to cook. Replaced fuse, set the time, hit the start cook and it ran for a second and the fuse blew again. Took it apart. Door switches seem ok. HV Cap seems ok. Read the right capacitance with my digital meter.
HV Diode voltage test with 9 V battery passed but I don't get any voltage if I measure resistance in either direction! Shows open either direction.
The magnetron resistance tests come out fine but if I shake it, it has a slight rattle noise!
Checking the internal light of the microwave found the light bulb to not be seated tight.
Any thoughts/comments what might be causing the 20A to blow?
Thank
vj K Testing the diode with 9V is no good. You need much higher voltage as stated in the video, or a meter that has a very high ohm range of at least 50M. Use your car battery with the engine idling. The usual culprits are a faulty capacitor, diode, and lastly the magnetron. If you can rule out the capacitor and diode, then swap out the magnetron. Make sure the HV transformer passes the tests.
Thanks For watching.
FYI is easy to follow ... My oven is not working ... I will follow this simple test only problem is I dont have a DVM... Maybe I can use 9volt battery connected to lamp as tester... Any good? Or there is a caution I needed to think like damaging a component? 😳😨🙏
If the high voltage diode is not reading with the 20m ohms is that means that is bad
Very good instructions. However, can I suggest you to add a test for the transformers low voltages ? You should test if there are no short between the secondaries.
The circuit board mounted transformer?
Yes, the little ones. It could happen, sometimes, that because of a default on the board driving to a peak of current a hot point between the secondaries. This is valid not only for the microwaves. You can use the mutimeter to perform the test. In case of any doubt, you can drive direct current into each secondary with your external source and test the other secondary from its two ends and, 2nd test, one end of it to the two ends of the first one under DC. Repeat this with the second end of the secondary considered. In fact, it is an insulation test between those secondaries to perform.
Hi , I have a GE Microwave JVM6172SK1SS that I got free , only problem is the exhaust fan won't turn off. I changed the fan relays on the board but still won't turn off. I checked the door switches and the three temp sensors all ok . What else do you think I could test
If the relays and temp sensors are OK, then it must be a faulty control board keeping the fan on.
@@electronicsNmore what would I check on the control board, what keeps the fan on untill it cools off enough to turn it back off. It must be stuck on. Thanks for your input. I don't care really want to replace the control board for they are over one hundred dollars, besides I like the challenge to try and find the faulty part on the control board.
What on the control board would be faulty for the exhaust fan to keep running ?
I have a GE profile. The front control panel lights up, but will not take touch commands. I took apart and cleaned all ribbon contacts with contact cleaner, and still no good. New boards are too expensive. Any thoughts?
jim bringe Usually a faulty door interlock switch. Test every switch and make sure they function properly as the door opens and closes.
Hey. When I test the Diode one way, I get 50M. When I reverse the leads, it starts to count up to infinity. I have a 2000M setting on my meter. I purchased a new diode and I'm getting the same readings on the new one. Is it possible that the new one is faulty as well?
Myth Your test showed a perfect diode. That is what the results should be. There was no need to buy a new diode.
electronicsNmore Ah, I see. I thought if the reading went over 350M it meant it was bad. Luckily I can return it. Thanks for all your help.
Most will rise up to the 300M range one direction, but I have seen others read to infinity. As long as one way is 30-55M and the other way is 300M to infinity, then you are OK.
Ok thanks for posting this video!! Question for ya, my GE microwave everything works but it does not heat and the turntable does not run! When it did this both stopped at the same time. Everything else sounds like it is running normal. What could cause both of these to go at the same time? Seems that they are not connected as far as what controls them or powers them. Even the display is still normal! PLEASE if you have any suggestions let me know! Excellent video just thought I would ask in your experience what could cause the two problems at the same time, so far I checked door switches and figuring out your instructions on checking the diode.
Sounds like a faulty door switch, OR when the door closes, contact is not being properly made to trigger a switch. Test each switch according to the video, and open/close the door while you test to ensure they are being triggered. POWER OFF!(unplugged)
I have an LG microwave that would start when I pressed the button, but would brown out and blow the breaker. Took the cover off, and the transformer was fried literally. Replaced the transformer, checked the capacitor, diode and magnetron, all checked out ok. Put it all back together, and it's still doing the same thing. Looks like it's trying to draw too much amperage on starting of the magnetron, then blows the breaker. Could it still be the capacitor even though it tests ok?
thanks!
Sean
You can try unplugging the microwave, discharging the capacitor as shown in my video, then unplugging the red HV wire from the transformer and leave it at least 1" away from any metal parts. CAREFULLY without touching ANYTHING inside the oven, stand back and plug in the microwave. Next, using the keypad, start up the microwave for a duration which would normally allow the problem to occur. If nothing happens, (everything works OK without heating), then you have a faulty capacitor, diode, magnetron, or you wired it wrong. Unplug the microwave when you finish the test. You do this at your own risk. Do it wrong, and touch anything while powered up, and you can be killed.
Canl you make a video repairing a turbo broiler including a circuit diagram tnx
Microwave capacitors will usually have built-in resistors connected to each terminal so that the capacitor will discharge automatically when the oven is switched is not in use.
Yes, slowly discharges with the internal 10M resistor. Thanks for watching!
I'm using defy microwave DMO 351... It powers on but the timer doesn't display nothing, now when I set on the timer it goes 1 second then trips what might be the issue
And am getting a higher voltage in my high voltage transformer
At the range of 170v does that mean the relay is bad
Outstanding video. Very detailed. Thank you for your effort. I have a situation and could use your expertise. I have a Kenmore Elite over the range microwave. My Son heated up some grub late at night and my wife came in in the morning and heard the microwave humming and could not shut it off. she pulled the plug and plugged it back in and everything was fine except it would not heat and would make a weird noise when she would try to use it. I took it apart and found that the Magnatron cooling fan shroud was melted and would not let the fan turn (ie weird noise). I cut the shroud from around the fan; put it all back together (to see if everything worked before ordering new parts) and everything works fine except it doesn't heat. My conundrum is:Should I even try to repair this? The only reason I can think of that the microwave was running when she woke up is that the filter was so clogged (didn't even know that there was a filter and has been there for 6 years caked in grease) that the system couldn't cool itself; the shroud melted, stopping the fan, which was getting a signal to cool the Magnatron. Which put it in a loop (glitch). Wouldn't even be wasting your time; but this is a very expensive microwave to replace and it's too cool. :) .Everything on the inside looks brand new and is probably the thermal switch that tripped but wanted your expert opinion on this before I started. I guess I would like to know if you have heard of "anything" like this? My problems are "never" easy. Thank you in advance for any help. Mark
Mark Schneider You need to test the parts according to the video. Not much else I can suggest. I have 2 videos on this subject. If everything tests OK, then replacing the magnetron is usually a good idea even if it tests OK.
electronicsNmore Any good leads on where to get a good cheap Magnatron? Amazon, Ebay or a better place? thank you, Mark
I have a Sharp microwave oven. Everything works except the digital display, including the clock of course. Any tips on the problem and how to fix it. Thanks in anticipation. I like this video. Very precise and clear.
ron martin Mhg Sounds like a faulty LCD display or faulty conttol board.
Thanks for the advice.
My GE microwave is properly working except when it is done heating up the food, and we open the door, the fan is still blowing. So what is the possible recommendation that you can give? And one thing more, can you show me how to make a wire to discharge the capacitor? Thank you.
Sounds like a faulty door switch. You need to test them all very carefully, and open/close the door as you test them. Make the microwave is unplugged, and test according to the video.
Good link here showing how to make the discharge tool.
1k to 10k is fine.
www.ifixit.com/Guide/Constructing+a+Capacitor+Discharge+Tool/2177
Thank you, I did test the capacitor and it tests normal I think at 9.37 for a 10 ohm capacitor and the terminal to body on each test infinity (followed your video). The buzzing is coming from the transformer. If I unplug the magnatron the tranformer still hums but the loud buzzing stops. Left the magnatron unplugged disconnected HV wire to the capacitor normal hum from the transformer but no buzzing. The tests of the transformer were all normal low side read .7 at 200 ohms and terminal to body was infinate at 20M ohms. High side .5 at 200 ohms and terminal to body was infinate at 20M ohms. The HV wire tested 91.2 at 200 ohms. I also tested the new diode and it was normal. I tested all the door switches, the thermo sensor, the fuse and transformers on the board all were normal. Again everything works except buzzing from the transformer and no heat, the magnatron is silent. I visually again inspected the magnatron, no cracks, sounds, etc... I also retested it and get .5 at 200 ohms and each terminal to body reads infinate at 20M ohms. Do you still think it is the magnatron?? and again THANK YOU VERY MUCH FOR THE HELP!!!
If you unplugged the magnetron from the transformer, then got only a hum and no buzzing, then that would indicate the magnetron is causing the problem. You need to swap out the magnetron. (0.5 ohms) for the magnetron is higher than normal.
Hey Mike.... Great video!
I'm looking for some advise before I can even think about trashing this older but expensive 1650 watt GE built-in oven.
I get the annoying buzzing BUT the oven does still heat at what seems to be it's normal heat rate.
Here is what I did so far.....
1.I did ALL the magnetron tests in your video. All tests were normal EXCEPT when testing across the 2 terminal plug on a 250 ohm setting, I get a reading of point five (.5) This is also the exact same reading I get when I simply touch only the 2 probes together. Does this indicate that there is a short since .5 is my starting resistance due to the resistance of the meter and probes itself?
IF yes, I do not see how the oven would still be warming! I also tried 2 other cheaper meters and each said resistance was one point zero. (1.0) Again, both meters tested at 1.0 when only touching the probes together. (Again I assume this is because of the normal resistance to the meter wire and probe itself and the meter just not being 100 percent calculated)
Do you think I have a full short in the mag based on the above reading?
2. Next, I ran ALL of your TRANSFORMER test. All were ok EXCEPT on the high power wire test I got a reading of 79.5 olm on my good meter and 80 and 79.5 on the other two cheapo meters that I have. I believe that you said between 80 and 140 or so was most common I am at the extreme low end or below....so could that be causing my BUZZZZ?
3. I also tested the cap and diode test. Both test were good. (did a test using a 9v battery for the diode) Both of those test we ok as I expected.
4. I removed the mag. Shook it. No noise. I also carefully looked for cracks and any burning on the head. The silver thingee that surrounds the head of the mag was nice and shiny silver but there is some kind of metal thing inside of that shiny silver part that was black.... but i assume that is normal....right?
5. I can not tell if the buzzz sound comes from the mag or transformer. I disconnected the 2-wire terminal plug that goes into the rear of the mag. When I turned the oven on, i did not hear any buzzing, but of course there was no heat :) I would guess that might not tell me anything since I assume that pulling out the mag might also stop the buzzing even if the transformer was bad and causing the mag to buzzz.
Any thoughts or questions would be really appreciated Thanks!
+MrUsaer
Hi there. I'm Doug. :-) 80 ohms on the HV secondary is fine. You can unplug the unit, discharge the capacitor, then unplug the red HV wire from the transformer leading to the capacitor and leave it sticking out and away from the metal chassis. Plug in the oven, stand away from the open areas(danger areas) of the oven, and TOUCH NOTHING except for the control pad. Enter 10 seconds and press start. See if the buzzing sound is gone while the oven is running, if it is, then you likely have a faulty magnetron even though it tests ok. Unplug the oven, discharge the cap again to be safe, then you can touch things.
It seems to me that MrUsears is having an issue with the mica lid that covers the openning of the waveguide in the oven cavity. Thanks for your video.
@@juanabreu5127 What can go wrong with those mica covers? Just curious.
Could you test them without disconecting from the microwave Sir?
I will have to watch the video again. Based on watching and replaying sections, I think my problem is the capacitor or the diode. I have a Sharp R-4A77 and it has 3 microswitches to the door. The instant I try to heat, it blows the fuse but the clock display is fine until I try to heat (I'll remove the good fuse shortly). I checked the operation of the 3 door micro switches with wiring pretty much removed (removed from wire harness), 2 NO and 1 NC, and they appear to function appropriately. What I find odd is the 1 NC when back in the wire harness has continuity when the microwave door is open or closed, but again, operates appropriately when removed from the wire harness. Sound plausible to you? So I believe you indicate if I am blowing fuses, it is likely the diode or the capacitor, correct? I am a bit leery on testing those but perhaps I will gain more confidence if I get the resistor you mention to discharge the capacitor. I would appreciate your thoughts as I hate to send the microwave to the land fill if repairable.
Mark Allen You need to test the capacitor and diode.
Hey elec my microwave packed in yesterday. Ive done all the testing that you said. It runs like all is well but does not get hot at all. everything tests good the magnetron is good and the capacitor is good i changed the diode still nothing. However i do get 2.5 ohms on my primary windings of the transformer any idea do you think that transformer is the problem the HV wires are fine to what you said and none of the wires short to the casing? Thanks man hope to get it working got no cash for a new one:) i get the tell tale hummmm from the transformer and all but nothing.
If the diode is definitely good, as well as the capacitor, then I suspect a faulty magnetron.
electronicsNmore thanks elec the diode is brand new so that should be good. i do struggle to test cap though as i only have 2m ohm on my meter. if i test across the terminals i get it count past 2m ohms not sure if that means the 10m ohm resister is good in the cap or not. the magnetron tests good but i guess there could be something wrong with it. anyway thank you so much elec solid video man keep it up.
Cap sounds like it is good. Likely a faulty mag.
My HG m-wave runs & hums, and does the deep hum as if it's heating. I tested the major components and they all passed, except possibly the HV diode between the capacitor & chassis. It passed the tests except the last ohm tests without the battery, it didn't change readings for that. It looks & sounds like it's running fine, just doesn't heat. Any ideas?
Usually the diode, capacitor or magnetron last. The magnetron can test OK, but still be faulty. You have to be absolutely sure the diode and capacitor are good before swapping out the mag.
Hello,
I have a GE microwave and it once blown up the noise filter fuse. I replaced it and it blew again. So the next possible test is door switches and that was the problem. I ordered the switches online and changed them too but this time my breaker went off. Did I miss anything here? Also my switches looks good as per your test videos. When ever the door opens the fuse blow. Can you help me pls.
Sounds like a fault capacitor or magnetron.
electronicsNmore magnetron test was ok. Should I check the capacitor then?
If the switch wires plugged in wrong would that going to be a problem?
The magnetron test isn't 100%. If everything else tested OK, then the magnetron is faulty.
Hi My meter reads 1 at 200 ohms open circuit (not 0.L like yours) and 0.7 closed circuit. I have checked the magnetron and it shows 0.7 ohms across the terminals directly from the meter with no jumper wires. When I use 2000k ohms to terminal and body it continues to read 1. Does this mean that it is faulty?
Your meter is not calibrated. When you touch the probes together you should have ZERO ohms. I think your due for a new meter if you cannot open and calibrate it. If you set the DMM at 2000k and you notice no change in the reading from each terminal on the mag to ground, then your OK. Understand this test is not 100%. If everything else tests OK according to the video, then usually the magnetron is faulty. Buy a new meter and repeat the tests. All the info you need is in the video, as well as in all the comments below.
Thanks For Watching
Are the Magnetron interchangable for different microwaves??
Mark E As long as the mounting bolts match up, the wattage is very close, and the size of the aperature is close, it should work just fine.
Hey Doug.... No buzzing after following your instructions below. I am going to buy a new magnetron and hope for the best.
I was curious about 2 things.......
1, When I followed your instructions by disconnecting the red HV from the transformer, would the mag be getting power from the other wire going from the capacitor to the mag?
2. Would you expect that low-end 80 ohm reading that I have on the HV secondary to gradually get lower as the oven gets older and result in less effective heating for cooking?
I will post back the outcome once i receive the new mag from online purchase and plug her in. Thank you very much for your help!!!
+MrUsaer
You're certain the capacitor and diode are both good? If so, then try a new magnetron.
+electronicsNmore
Yes, pretty sure.
I did the cap tests per your video and did the 9v battery test for the diode....which I believe I read later that you were not a fan of.... anyway, the diode test showed full 9.3 volts one way and about 6 volts the other way as best I recall.
If the mag ordered online does not work I am allowed to return to the seller. So not a big deal if it turns out to be something else. Should have it by Friday or Monday..... Will let you know... Thanks again!
Thanks for uploading this was so helpful! While testing the transformer, the resistance between the single high voltage wire and the body of the core did not change the reading from OL. Does this mean the transformer is broken?
Place the digital meter on a low ohms range(up to 200 ohms or 1k ohm) You should get a reading. Be sure to scrape the transformer core in the area you test from. There is an enamel coating which must be removed to expose bare metal prior to testing.
Thanks for watching. Be sure to rate Thumbs Up, and share my channel with others.
electronicsNmore That did the trick! It was reading 154 ohms. Thanks :)
hello there...Could u tell us something about the causes of blown HV fuses?
Some microwaves blow fuses when a door switch is faulty. A bad capacitor or diode can also cause the problem.
What model DMM do you use in this video ? Thanks.
Wavetek 27xt, but I also use another very good DMM which I made a product review video for. The DMM is a Mustool. Please refer to my "Product Review" video playlist. Thanks
A very informative tutorial. Many thanks.