Need assistance to find a short in power supply on BD1000a1

It seems half of the power supply is working correctly, but the other half has a possible short somewhere. With a 5 amp fuse inline with +B and only 1 FET on the Q5-Q8 (Q9-Q12 empty) side it will pop the fuse instantly. If I have 1 FET installed on the Q9-Q12 (Q5-Q8 empty) side it will power up green light and all. I started playing around trail and error style, and removed all the transformer leads for Q5-Q8. I also removed +B so only ground and REM power connected. With 1 Fet on both sides (1 on the Q5-Q8 side and 1 on Q9-Q12 side) installed the voltage to the gate on the Q5-Q8 side is ~2.3v if I connect the transformer lead back to the board the voltage jumps to 6v then it gets hot.

I have attempted to find this "short", but everything I've tested seems to be OK. I have even gone to the extent of removing the transformer to test the leads which i didn't find any shorts weird resistance readings. Tested Q17/Q20 (and they were replaced with new), have also tested D16, and i'm not fully sure how to test a switching diode for D15. U14 voltage on pin 13 was 5.45 and pin 16 was 5.30. Pretty sure I'm overlooking something, or not doing something correctly.
I can remove it again to double check the transformer windings. I pulled it out once, but didn't find any weird readings as each winding didn't seem to cross anywhere. Maybe it's shorting when it's installed? As a side note I can have the gate and drain connected on the Q5-Q8 side with +b and rem connected, but as soon as I connect the source it pops the fuse.

I also do not have a current limiter. It's just a 12v 50A capable power supply.
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For future reference, pulling an intermittently shorted inductor or transformer can make it much more difficult to find the fault. One of the first things you do is to push/pull/twist it while operating through a limiter (you should have one if you're going to do repair work) to see if the current draw changes.

Operating through a limiter with the FETs clamped makes it virtually impossible to damage anything or blow fuses.
You need to insert an insulator in-between the windings at the point where they are shorting. It can be as simple as piece of cardboard with a bit of adhesive to keep it in place.

The next time you order parts, buy a 2 ohm 100w resistor like the one shown below to use as a limiter. If you buy 2, you can use them in series for a 4 ohm dummy load. Fan cooling from the end (through the hollow core) will significantly increase their power handling.


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Ah yes that makes sense. I'll do that for next time for sure.

I did make a mistake, and I really screwed it up... It was starting to look promising although disaster struck. When I was putting in an output fet to see with no power to the amp at all not even the cables connected. It basically blew out a fet as soon as it touched the pads. In turned screwed up something else as I lost half the power supply again. I lost all power on the gate of the power supply fet. *sigh*
Thanks for the tips, but I was unable to find exactly where the short is on the transformer or maybe i'm just losing my mind haha! I can't get it to power up with a fet in the Q5-Q8 side again. With +B and ground only the fet gets really hot super fast, but didn't pop the fuse. with +B, REM, and ground it pops instantly. Then with REM and ground nothing happens. So i've again reduced it back down to the same issue as before, but no matter how much I twist/turn/push/pull the transformer nothing changes with the voltages on the pads and nothing makes any noise. I validated everything from U14 through the Q17-21 and everything around it... so I'm definitely back to this transformer...i think. Only weird thing (outside of some short i can't seem to find) I noticed was that U14 Ouput A (pin 13) has ~2.45v whereas Output B (pin 16) has ~3.15v.
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