Usually easy to test mosfet like this, but in a circuit board without desoldering it, the gate to drain resistance conducts away the gate charge rapidly so you can't use this method. Here's how to do it: Just connect an extra probe wire to the DMM positive probe and clip it to mosfet gate on the pcb itself or a circuit track there, and then measure drain to source resistance, with your dmm probes, you will see the same conduction! It will go back to high resistance immediately you unclip the gate extra probe! By bleeding the charge thru gate to ground resistance present on any mosfet using circuit. Some technicians use a 9 v battery with leads soldered to it and connect to gate and ground on circuit board, then use dmm to measure drain to source resistance! Use either method.
may not work with a better quality meter as usually the better the meter the less load it puts on the components not all the time but sometimes an analog meter would be good for it too, love your test thankyou
In testing/checking MOSFETs using Multi-meter, when the gate is charged, why some MOSFETs (N-channel & P-channel), the drain to source let us say 0.002 or less reading, others starts with more higher like 0.435 and running up as fast as a second or half a second until showing infinite? What does it mean? Does all MOSFETs behave like that?
Hey man, thanks for this video, I don't know much about the more advanced parts of electronics, but I'm currently repairing a car audio amplifier that uses N channel MOSFETs, which are known to go bad in this specific model. I'm using a cheap harbor freight cen-tech meter, on the diode mode. This amp uses 8 IRF3205 MOSFETs and 6 IRFB4227 MOSFETs. I've clipped them all off for now (I know probably the hack way to do it, but I don't have a good soldering iron and don't want to damage the amp's 2 layer PCB.) I got to the third 3205 using this basic test, the first two behaved exactly like yours did, but this third one immediately dead shorts (I believe?) and sets off the meter's beeper after I apply the lead to the gate lead then to the drain lead, as I did with the others. Could this indicate a defective MOSFET? I'm hoping it is, once I get all of these tested I'm tacking the remaining good units back into the amp which should allow it to work for testing purposes (given with less power output until I buy replacements for the bad MOSFETs.) Glad you made this video, only one that explained the testing procedure in a way that makes sense.
Update: Two of the 3205s ended up dead shorting, the other 6 tested fine. Could not get any of the 4227s to work, at least not with this specific meter doing the same test, which is odd because they use the same GDS pin layout as the 3205s do (checked multiple datasheets for both). I'm just going to assume the 4227s all as good for now, because even just testing them for continuity there was no dead shorts. Will see how the amp behaves with the two suspect 3205s pulled from circuit. I have a second one of these amps, also dead from the same issue, so I should have the donor parts to use to get one working, then eventually both.
Nice presentation. Please, can I use this method to test a mosfet the pcb? & I wish you could have test a bad mosfet on the $8 tester, just for us to see how it reads. Finally, kindly let me know if 3205z and 3205 can be substitute. Greetings from Nigeria.
Hello, I know this vid is pretty old but can't seem to find an answer with Google. Mine works as yours until I put the positive back onto the drain then the voltage drop rises until it is back in the off state. If I just touch the gate with positive again it will do the exact same thing. Assuming it's naffed but not 100%
Okay got a little confusion,I have several Mosfets IRLB3034 I have a fluke 77 series, witch I test the Mosfets on and I have some questions to whether witch ones are good and witch ones were bad, When I test one on a setting that has diode and continuity setting, only bleeps as shown in your video so that,s good , but the number creeps up slowly starting from 6.68 up to 3.000 then goes to 0 then starts going back up again, If I set it on ohms it goes up to 32.42 M ohms then goes back to LO, The other Mosfet IRLB3034 I set the multi meter back onto diode and continuity test ,it Bleeps as should as shown in your video but on this one the number flashed up 0.92 comes up quickly then quickly goes away. Witch Mosfet is the good one and why ,
I am trying to test a MOSFET using this method. In the ON state, the drain and source show continuity for a very brief duration, like half a second, and then opens again. I am not sure if this MOSFET is faulty of not. Any advise please.
I tried to do this using a craftsman 82008 multimeter and can not get any reading , yet if I use a super cheap cen-tech multimeter the mosfet behaves like you say in your video. Do you know of any reason for this? I thought a better multimeter like craftsman would yield better results.
Iv done this with old mosfet and a new one and the reading goes up then back down straight away the meter is in diode mode but is an old meter only showing l instead of OL does this mean that both the mosfets are ok or faulty .
This method only works with logic level MOFETs since the gate voltage required is quite small. Power level MOSFETs will require a 9V battery to test it. Right?
Hey so I have 12 mosfets in total and I tested them most of them come back good with three digits like in the 0.108 or but a few of them came back still three digits but 0.002 or 0.004 are these ones still good or does 02 mean short?
I touch the gate but between source (black on dmm) and drain (red on dmm) there is a very short spike with diode sign shown on DMM (continuity mode) and shows 1.8-1.9v and quickly shows OL. what does that mean? if I lift drain and put it back it again shows diode voltage and OL.
great little video.. but i can't get any readings at all no matter what connections i make . the G, D and S are the same as in your video .. i am testing a STW80NE06-10 Mosfet .. . does this mean it's completly blown ..
Late answer, but yes it does! If you happen to be working on something similar to what I am (a Rockford Fosgate car audio amplifier), this is the same process for the IRFB4227 MOSFETs as well. In the future, you can figure this out easily simply by looking on Google for the datasheet, which will tell you the type and specs of the part you are working with.
Thank you, when i touch gate and test i have voltage for 2 sec then it opens, and i tested a second one and the voltage is going up slowly until it opens, is it bad ?, because your vid say it should hold
Its could creep back to not conducting. Hold neg on source pin. Charge gate 5 seconds with pos from meter. Then check the drain pin again with meter pos lead. But yes it could creep back to being open or non conductive. When I test N channel mosfets I hold neg meter lead on source pin. Make sure it is open on drain pin with pos meter lead. Then I charge gate 5 sec with meter pos then meter pos back on the drain to confirm continuity. If you ever have a short on any pin then fet is bad.
Quick and Dirty. MOSFET confessions! I bet you can get them irf z44n's at the grocery store! they are everywhere. I'm thinking about trying to add FETs. to a lithium ion battery balance board/protection board. but on a separate board. to add balance current. and maybe discharge protection current. I'm mostly needing balancing for when charging. I almost think I will not need it. I don't want to end up saying. "I didn't think it would burn the house down" that's done happened 2 years ago. I had nothing to do with it! I just can't handle it again!! I know I need a Batrium system but that's near $500 and only balances and protects the batteries. it don't really "DO" anything to make things work. its not a charge controller. or anything like that. and it has all kind of extra Goody's. you can connect rgb neo pixels . to it it foes who knows what. and Bluetooth monitoring WiFi lots of stuff. I don't need. but is extra. the main board I heard is $365, plus long Mons for every parallel cell. maybe $50 ea. I'm running 7 cells in series. so maybe $350 for that. so near $1000, so I'm looking for cheaper options. in so tight one day I'm going to need some WD. to get my wallet open! keep teaching us professor! and hope you have a great day. and well thank you!
Best tutorial for testing mosfet, i salute you from philippines
Learning loads on your channel. We don't all have fancy meters! Built a wee esr meter recently and am impressed!
No one explained to me mosfets like that. Awsome. Thanks.
Simple explanation, easy to follow the instruction. This is a good tuitorial, thank u. Nice one.
RelY731
I like your Channel, I'm new to electronics and Your explanation Was 100 % UNDERSTOOD . Thank You
Glad to help
It's best MOSFETS testing method.Thank you sir
Easily the best video on testing a mosfit . Thanks .
Looks very simple to test. Thanks a lot.
Best video on this, hands down. Thank you.
What a nice and informative video! Thank you. You sure helped me out!
Usually easy to test mosfet like this, but in a circuit board without desoldering it, the gate to drain resistance conducts away the gate charge rapidly so you can't use this method. Here's how to do it: Just connect an extra probe wire to the DMM positive probe and clip it to mosfet gate on the pcb itself or a circuit track there, and then measure drain to source resistance, with your dmm probes, you will see the same conduction! It will go back to high resistance immediately you unclip the gate extra probe! By bleeding the charge thru gate to ground resistance present on any mosfet using circuit. Some technicians use a 9 v battery with leads soldered to it and connect to gate and ground on circuit board, then use dmm to measure drain to source resistance! Use either method.
Quick, but not very dirty! ;-) Nice, handy, quick field test! Good show as usual.
Short and well explained, i really enjoyed it, thanks.
Niiiice, couldn't be more simpler than this, thanks!
Fantastically simple
That's the best video I've seen all week, and I've seen a lot :D
Thank you for this. Well demonstrated
The testing probes are as excellent as you are sir,
Amazing tutorial demonstrating how MOSFETS work! Helped a ton ♥️
Must the mosfet be taken off the board to do this test?
Great demonstration, thanks lot brother.
Very very easy and usefully way to understand god bless you bro👍
may not work with a better quality meter as usually the better the meter the less load it puts on the components not all the time but sometimes an analog meter would be good for it too, love your test thankyou
Oh wow that was easy thank you, been searching for ages but all others were technical brain fry
Does this apply while they are still soldered in the circuit as the gate should be in the off position unless blown open?
Nice way to test Mosfets Thanks
Can I use your procedure to test this mosfet installed in the circuit board?
In testing/checking MOSFETs using Multi-meter, when the gate is charged, why some MOSFETs (N-channel & P-channel), the drain to source let us say 0.002 or less reading, others starts with more higher like 0.435 and running up as fast as a second or half a second until showing infinite? What does it mean? Does all MOSFETs behave like that?
Well explained, very helpful video, thank you.
Touching the gate with your fingers, like this jerk did, is not reccomended !!!
That was a dirty trick and i loved it. Any way to test in circuit?
Hey man, thanks for this video, I don't know much about the more advanced parts of electronics, but I'm currently repairing a car audio amplifier that uses N channel MOSFETs, which are known to go bad in this specific model. I'm using a cheap harbor freight cen-tech meter, on the diode mode. This amp uses 8 IRF3205 MOSFETs and 6 IRFB4227 MOSFETs. I've clipped them all off for now (I know probably the hack way to do it, but I don't have a good soldering iron and don't want to damage the amp's 2 layer PCB.) I got to the third 3205 using this basic test, the first two behaved exactly like yours did, but this third one immediately dead shorts (I believe?) and sets off the meter's beeper after I apply the lead to the gate lead then to the drain lead, as I did with the others. Could this indicate a defective MOSFET? I'm hoping it is, once I get all of these tested I'm tacking the remaining good units back into the amp which should allow it to work for testing purposes (given with less power output until I buy replacements for the bad MOSFETs.) Glad you made this video, only one that explained the testing procedure in a way that makes sense.
Update: Two of the 3205s ended up dead shorting, the other 6 tested fine. Could not get any of the 4227s to work, at least not with this specific meter doing the same test, which is odd because they use the same GDS pin layout as the 3205s do (checked multiple datasheets for both). I'm just going to assume the 4227s all as good for now, because even just testing them for continuity there was no dead shorts. Will see how the amp behaves with the two suspect 3205s pulled from circuit. I have a second one of these amps, also dead from the same issue, so I should have the donor parts to use to get one working, then eventually both.
Tell me more about the Bang good component tester. I would like to get one and learn how to use it.
Great video
/Bklyn👑
Why didn’t they just left the Gate in the middle.like the other transistors?
AWESOME!!!!!!!! THANK YOU, FOR THIS CONCISE, PRACTICAL LOOK AT MOSFET TESTING!!..
Can I do this in circuit
Very helpful i was able to repair my inverter thankyou
I love you soooo much THHHHXXX, you have no idea how your savings me.
All other vids were shit and I couldn't understand
Great info this
Do you have anything on testing spike absorbers?
Nice clean explination
All the other videos demonstrating this only confuse me but after watching this video a few times it finally sunk into the old brain. lol
good job. ez to understand .
is this also the case when the mosfet is in circuit?
Awesome info man!
Nice presentation.
Please, can I use this method to test a mosfet the pcb? & I wish you could have test a bad mosfet on the $8 tester, just for us to see how it reads.
Finally, kindly let me know if 3205z and 3205 can be substitute.
Greetings from Nigeria.
that's great video thank you,,, I wonder if possible to test it the MOSFET onboard is it the same way?
STRAIGHT TO THE POINT!!!
Small detail: mosfets don’t have Vcc and Vee, but Vdd and Vss
Excellent!
The shorter explanation and ther best, thanks
Hello, I know this vid is pretty old but can't seem to find an answer with Google. Mine works as yours until I put the positive back onto the drain then the voltage drop rises until it is back in the off state. If I just touch the gate with positive again it will do the exact same thing. Assuming it's naffed but not 100%
Is that conduction value on the data sheet somewhere?
Freakin cool dude. So simple. Question: Is it necessary to remove Mosfet from PCB to test? Especially 8pin dip type.
Mine didn't develop a capacitance between g and s until i disconnected it, perhaps u need to
Thanks for sharing 👍
Okay got a little confusion,I have several Mosfets IRLB3034
I have a fluke 77 series, witch I test the Mosfets on and I have some questions to whether witch ones are good and witch ones were bad,
When I test one on a setting that has diode and continuity setting, only bleeps as shown in your video so that,s good , but the number creeps up slowly starting from 6.68 up to 3.000 then goes to 0 then starts going back up again,
If I set it on ohms it goes up to 32.42 M ohms then goes back to LO,
The other Mosfet IRLB3034 I set the multi meter back onto diode and continuity test ,it Bleeps as should as shown in your video but on this one the number flashed up 0.92 comes up quickly then quickly goes away.
Witch Mosfet is the good one and why ,
Hi
What’s the mean When touch the gate and put the lead between drain and source and show zero or short circuit on multimeter?
Perfect!!!!
Question. Do i have to take out the mosfet from the pcb to do this? Or i can also test it while it is still in the pcb? Thnkx.
I am trying to test a MOSFET using this method. In the ON state, the drain and source show continuity for a very brief duration, like half a second, and then opens again. I am not sure if this MOSFET is faulty of not. Any advise please.
Will it also work for MOSFET with body diode?
Fantastic.thanks.
I tried to do this using a craftsman 82008 multimeter and can not get any reading , yet if I use a super cheap cen-tech multimeter the mosfet behaves like you say in your video. Do you know of any reason for this? I thought a better multimeter like craftsman would yield better results.
Do I have to remove them to test them?
What if the value from on state drain(red probe) to source(blqck probe) is raising and turns back to 1 is rhat good?
Great tutorial.
Awsome man thanks, helped me out
Iv done this with old mosfet and a new one and the reading goes up then back down straight away the meter is in diode mode but is an old meter only showing l instead of OL does this mean that both the mosfets are ok or faulty .
Very clear thankyou
this helped me !! thak you
+all motor welcome
The GATE can be discharged if it is shorted to the SOURCE and not to the DRAIN.
Mmmm that was quick and dirty. I need a wash. 👍
good, could make a video to show how to know the mosfet is fake or original ?
This method only works with logic level MOFETs since the gate voltage required is quite small. Power level MOSFETs will require a 9V battery to test it. Right?
I didn't use it on logic level.
Hey so I have 12 mosfets in total and I tested them most of them come back good with three digits like in the 0.108 or but a few of them came back still three digits but 0.002 or 0.004 are these ones still good or does 02 mean short?
Tnxs.for the info sir!god bless!
Magic!
I touch the gate but between source (black on dmm) and drain (red on dmm) there is a very short spike with diode sign shown on DMM (continuity mode) and shows 1.8-1.9v and quickly shows OL. what does that mean? if I lift drain and put it back it again shows diode voltage and OL.
idk if it helps its an ST Micro STD20NF06L
Simple is Good!
can a mosfet be tested in a motherboard
Awesome
Can it be test in circuit?
thanks alot!
Usefull
how can I tell which is mosfet and which is bipolar transistor they all look alike
When i touch the gate and than the drain I have continuity but only for 1 second or less it discharges very fast
great little video.. but i can't get any readings at all no matter what connections i make . the G, D and S are the same as in your video .. i am testing a STW80NE06-10 Mosfet .. . does this mean it's completly blown ..
+REDBARRON2424 I am not familiar with that MOSFET so I can't give you a definite answer. I would say check the data sheet for specifics.
You are really intellectual .
Does your process of testing the N-channel MOSFET applies to IRF3205 mosfet?
Please I need answers, thank you 😁
Late answer, but yes it does! If you happen to be working on something similar to what I am (a Rockford Fosgate car audio amplifier), this is the same process for the IRFB4227 MOSFETs as well. In the future, you can figure this out easily simply by looking on Google for the datasheet, which will tell you the type and specs of the part you are working with.
Thank you, when i touch gate and test i have voltage for 2 sec then it opens, and i tested a second one and the voltage is going up slowly until it opens, is it bad ?, because your vid say it should hold
Its could creep back to not conducting. Hold neg on source pin. Charge gate 5 seconds with pos from meter. Then check the drain pin again with meter pos lead. But yes it could creep back to being open or non conductive.
When I test N channel mosfets I hold neg meter lead on source pin. Make sure it is open on drain pin with pos meter lead. Then I charge gate 5 sec with meter pos then meter pos back on the drain to confirm continuity. If you ever have a short on any pin then fet is bad.
Super 👍
I can't see your pin on 4:55
Good
Quick and Dirty. MOSFET confessions! I bet you can get them irf z44n's at the grocery store! they are everywhere. I'm thinking about trying to add FETs. to a lithium ion battery balance board/protection board. but on a separate board. to add balance current. and maybe discharge protection current. I'm mostly needing balancing for when charging. I almost think I will not need it. I don't want to end up saying. "I didn't think it would burn the house down" that's done happened 2 years ago. I had nothing to do with it! I just can't handle it again!! I know I need a Batrium system but that's near $500 and only balances and protects the batteries. it don't really "DO" anything to make things work. its not a charge controller. or anything like that. and it has all kind of extra Goody's. you can connect rgb neo pixels . to it it foes who knows what. and Bluetooth monitoring WiFi lots of stuff. I don't need. but is extra. the main board I heard is $365, plus long Mons for every parallel cell. maybe $50 ea. I'm running 7 cells in series. so maybe $350 for that. so near $1000, so I'm looking for cheaper options. in so tight one day I'm going to need some WD. to get my wallet open! keep teaching us professor! and hope you have a great day. and well thank you!
Try eBay. The balancing boards with MOSFETS are less than $10. Just checked it : current voltage regulator modules (with meter) are less than $15.
I was looking for this video: don't want to spend $8 on a test device :)
Hi can this parts be damage by ambient temperature changes
I Always Loved Playing In The Mud A Weeds. Lol.
👍
Another tidbit about mosfets - they are ESD sensitive and should be handled in a static safe bench with a grounded wrist strap.
Have a suspected bad one thats not doing it that way
"OL" is not zero! is "Open Line"
Well, if you want to picky it's not open line either. It's "open loop."
I reckon you never lost an apprentice if they were smart enough to listen