rather than touching the legs of the mosfet to discharge the gate when testing with a meter in diode mode, you can just put the +ve lead on the source, and the -ve lead on the gate - that will discharge the gate capacitance and turn the mosfet back off
Hi mate! thanks for the video! Just a question, where did you get the PSU schematic? Im struggling for a while to find PSU schematic for TDS380 and 420A. Gday
Nice tutorial video. I have Hameg 1004-3 oscilloscope and by mistake I shorted DC output wires during reassembling it. Now, oscilloscope turns on and turns off and cycle goes on. Any suggestion will be highly appreciated. Thanks.
Ive got the newer version without the c17 cap. same symptoms, q5, q6 blown. I replaced q5,q6, everything else i could find in the chain passed. When I reassembled I momentarily got the green lights for about a second or 2 then the fuse blew again. checking it took out Q5 also. thoughts? i couldn't find the other tvs diodes and transistors you referred to, waiting for pcbway to deliver the test board. thanks for designing that. seems strange indeed.
Thank you for doing this, always enjoy your videos, I had PCBway do a run of the 1.2 board and ordered the parts from Digikey, it works fine but noticed a difference on your video that the -PF led stays on but on the board I did it only stays on while I depress the momentary switch and goes out when I let go but power on all other outputs stay on like they are supposed to. Any thoughts?
An awesome video. I have a 744A with no display the VGA on the back works, it's just something in the display unit that not working. Thanks for sharing. Did KO4BB take down the schematics, I can't find them on the website anymore? If so do you have a link to them. Best Wishes & Blessings. Keith Noneya
Check here, the display schematics will be the same across all colour screen models, also the relevant parts of the processor board will be pretty much identical too. w140.com/tekwiki/wiki/TDS544A
i actually have an tds 644b with 684 board(the original board has been take a shower on capsfluid and drop the magic smoke) i change it his board and the caps in new boar, but still not working (only turn on and off every second) maybe need to check power supply too
22.17 do you have specs on those diodes? Looks like one of them is pulled out on mine for some reason the other one doesn't have any numbers just looking at the top of it...looks like one was pulled out at some point. Are these diodes the same? hmm..that's good think you did you video I didn't even see that missing diode - had a different issue than power supply. P.S. never mind u mentioned the part number later ebay got a bunch LOT OF 10 GI 1.5KE220CA SEMICONDUCTOR DEVICE DIODE 0024E
Another great tut = thanks! You taught me some new things about Low ESR e-caps and why it is important to match their specs exactly.
Professional service and fix, the idea with the testcard is great.
Yes bit he dont see the ripple noise thats why i dont like these cheap multimeters i use dual display multi it show DC and AC
Fantastic. Thanks for sharing the test board files. I will definitely use it, as I have one of those psu to be fixed.
Let us know how you go! If you install higher wattage, lower value resistors, you could do a higher current load test too.
rather than touching the legs of the mosfet to discharge the gate when testing with a meter in diode mode, you can just put the +ve lead on the source, and the -ve lead on the gate - that will discharge the gate capacitance and turn the mosfet back off
Thanks a lot!
Hi mate! thanks for the video! Just a question, where did you get the PSU schematic?
Im struggling for a while to find PSU schematic for TDS380 and 420A.
Gday
Nice tutorial video. I have Hameg 1004-3 oscilloscope and by mistake I shorted DC output wires during reassembling it. Now, oscilloscope turns on and turns off and cycle goes on. Any suggestion will be highly appreciated. Thanks.
Ive got the newer version without the c17 cap. same symptoms, q5, q6 blown.
I replaced q5,q6, everything else i could find in the chain passed. When I reassembled I momentarily got the green lights for about a second or 2 then the fuse blew again. checking it took out Q5 also.
thoughts? i couldn't find the other tvs diodes and transistors you referred to, waiting for pcbway to deliver the test board. thanks for designing that. seems strange indeed.
Thank you for doing this, always enjoy your videos, I had PCBway do a run of the 1.2 board and ordered the parts from Digikey, it works fine but noticed a difference on your video that the -PF led stays on but on the board I did it only stays on while I depress the momentary switch and goes out when I let go but power on all other outputs stay on like they are supposed to. Any thoughts?
Muito bom trabalho. Parabéns.
An awesome video. I have a 744A with no display the VGA on the back works, it's just something in the display unit that not working. Thanks for sharing. Did KO4BB take down the schematics, I can't find them on the website anymore? If so do you have a link to them. Best Wishes & Blessings. Keith Noneya
Check here, the display schematics will be the same across all colour screen models, also the relevant parts of the processor board will be pretty much identical too.
w140.com/tekwiki/wiki/TDS544A
That is a huge power supply
i actually have an tds 644b with 684 board(the original board has been take a shower on capsfluid and drop the magic smoke) i change it his board and the caps in new boar, but still not working (only turn on and off every second) maybe need to check power supply too
what solder extractor are you using, my Pace MBT250 sucks but only metaphorically :)
Friend, in which electronic store did you buy the Mosfets transistors?
It was either Mouser or Digikey, either or both should have stock.
22.17 do you have specs on those diodes? Looks like one of them is pulled out on mine for some reason the other one doesn't have any numbers just looking at the top of it...looks like one was pulled out at some point. Are these diodes the same? hmm..that's good think you did you video I didn't even see that missing diode - had a different issue than power supply. P.S. never mind u mentioned the part number later ebay got a bunch LOT OF 10 GI 1.5KE220CA SEMICONDUCTOR DEVICE DIODE 0024E
There are two different TVS diodes used, here are the part numbers:
VR4 ‐ 1.5KE220CA
VR5 - 1.5KE250CA
@@NearFarMedia copy that - thanks.
Awesome 👍👍
Where did the schematic for the Tek PS come from? The Service Manual I downloaded didn't have schematics.
Did you ever get a copy or find where you could acquire some?
No. Never did.@@keithnoneya
I have a TDS 754A. I am looking for schematics, is someone knows where to get the schematics?
Hi, when I go on your pcbway shared page, I don't see this power supply board. Can you help direct me to where I can order it. Thanks, Rob
You can find the gerber files linked in the video description....
gate drain source not ground drain source
Good catch!