Sanyo Mosfet intermittent maximum output spikes

[litewate]

This amp is a:

Sanyo Mosfet DC power amplifier Plus PSS.

The amp will work normally then without warning, send the maximum output to the speakers (A or B channel); the circuit breaker kicks in; then it is back to normal for a bit.

Any idea or suggestions on how to repair this?

Aloha, Neal

 

[mikeks]

Passlabs..

One good reason to change to Pass' Aleph series of amps...particularly the 'o'....no funny spikes on program....

...rather tough to get a grip on that....total absence of such is generaly a hallmark of quality amp.....

 

[anatech]

May take a while to find

Hi Neal,
Check solder connections first. If this still happens, warm up some transistors one by one. They may go open when heated. Do not have your speakers connected when doing this! Next, use some cooling spray and give the transistors a small shot. Wait between transistors as the effect is thermal and may take 20s or so.
I have had capacitors & resistors do this too. I track 'em down with a 'scope as I "tease" the unit.
The Mosfet output stage doesn't make this any different to troubleshoot than a BJT output amp.
-Chris

 

[litewate]

Thanks for the input. Will take it to a friend's house and run troubleshoot it there.

Aloha, Neal