P500; low regen output; help!

my P500 output from the filtered AC is fine. the fuses are fine too. however, the regen outputs are low. in auto mode i get up to 70 volts AC (58 right now; seems to go up a bit when the unit warms up); in the other modes it drops about 10 volts.

i opened the case and see nothing dramatic. i used my peak ESR meter to test the large caps on the regen circuit.
C5 3610uF 0.58ohm ESR (some evidence of deterioration)
C3 3652uF 0.6ohm ESR
C1 3464uF 0.56ohm ESR
C2 5992uF 0.08ohm ESR
C4 6440uF 0.08ohm ESR
C10 6354uF 0.1ohm ESR
I called PSA and was told you no longer service the P500s. I was told you could send the schematic
I have a local tech who can hopefully look at this but has COVID; hoping for his full recovery!
if it is just replacing the power supply caps i can do that myself :slightly_smiling_face:
any tips would be appreciated.


@jamesh may be able to obtain and send you a schematic.

Good luck!

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Just send over an email with some schems. Best of luck!


Please let us know how it works out.

the schematic says the power caps are supposed to be 3300 uF and 100v (they are polar caps). at least some of them are measuring way off from that. another one had some signs it was dried out.

seems like a good 1st step would be to replace those caps. does that make sense? if that doesn’t fix the problem i’m going to hope my tech can sort it out.

No question a great place to start!

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how do these look?

Seem great!

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OK, ordered

mouser deliveries were running slow. the new caps finally arrived and i installed them last night. the old caps were definitely dried out (at least most of them were). alas, this has not solved the problem. set on auto, the regen outlets are producing about 83 volts AC. that is an improvement over the high of 70 volts AC i noted above. i’ll leave it plugged in and see if i can any more gain–it did take a while for the readings to slowly ramp up last night. right now the voltage seems to be stuck at this new high.

replacing the caps is within my competence, but troubleshooting beyond this easy fix is not.

any thoughts? many thanks!

This level of troubleshooting is outside of my wheelhouse as well. Sorry the new caps didn’t fully bring it back to life. At this point, it might be best to send our service team and email and see what they think. service@psaudio.com

OK, thanks!