A/D/S power plate 80 and 100

[Perry Babin]

With some amps, applying both B+ and remote together can cause problems. If it doesn't with this amp, it's OK.

For the negative diode, move the end that goes to the transformer to the same transformer winding as the positive diode. Does that give you both positive and negative voltage on the caps?

Are there any broken wires or solder connections on the transformer windings?

[Rabbit 16v]

Well it did get me thinking that caps might be a thing by removing the ground. I will reconfigure the setup for turning it on.

Still not reconfigured though, yes that give me 33v both pos and neg with reference of negative test lead on the caps.

I cant see anything on the transformer that indicates open circuit or anything.

[Perry Babin]

If only one transformer winding (of the two that went to the AC of the bridge rectifier), it would seem that one winding either has bad connections or a broken wire.

Heat all of the solder connections for all of the various transformer windings to see if the wires for any just fall over when thoroughly heated.

[Rabbit 16v]

This seems like we are getting closer. Hope its not the transformer, those probably arent easy to find.

I did heat them all and nothing obvious changed. Retouched the solder connections and no change there either. Next step is to pull it from the board and test on the bench for resistance then, I assume?

[Perry Babin]

I don't know how clearly the windings are laid out. If they're confusing, try to check them with resistance.

What's the resistance between the two windings that feed the AC terminals of the bridge rectifier?

Between those windings and the ground between the filter caps (orange arrow)?

[Rabbit 16v]

They arent too confusing, but the schematic we are going with isnt exact on this portion from what I can decipher.

resistance between the two points of AC input to the bridge rectifier are about an Ohm.

same resistance between orange arrowland and those same points as mentioned above.

[Perry Babin]

Using the ground between the capacitors, do you have a square wave on both AC terminals for the bridge rectifier?

Are they the same amplitude?

[Rabbit 16v]

Yes and yes.

[Perry Babin]

This is confusing. The bridge rectifier, if intact, was pulling from both windings but never produced the positive rail. The individual diodes will produce both rails if pulling from one winding but not from the other, even though both windings have the same waveform.

Do you have a 120v incandescent (not CFL, not LED) lamp (lower power would be better)?

[Rabbit 16v]

Right?? Very confusing and likely my fault for not getting all of this. Of note, not on all tests until recently have I been screwing the PS transistors to the heat sink. So maybe that matters?

I do have a 120vac 25w incandescent bulb here that I used earlier.

Maybe since I have all three wires disconnected from the PS to audio board, I might try installing the OG rectifier and testing with both transistors screwed down? If them being screwed down is the issue, I feel like a total idiot.