So what were the results of the ESR meter test on the capacitors?
I am not even sure how you can test a capacitor with a multimeter and get
any kind of useable result for a failing capacitor. Beyond maybe a shorted
one.

David

"Peter" wrote in message
...
I have an electric piano that recently developed what I believed to be a
faulty capacitor.

The symptoms were that during playing for a few minutes I would start
hearing a sort of crackling sound coming from the speakers.
Then soon after I would hear a quite loud "pop" sound through the speakers
and then the sound would go dead.

I could still hear faint hissing through the speakers (as when the volume
is
up but nothing is being played) but hitting the keys would produce no
sound.
When I turned the piano off for a few minutes to cool it down, it would
play
again.

I could also smell kind of "fish" smell coming from the piano.

Anyway I opened it up and when it went dead again I sprayed all the caps
one
by one with a freezer spray.
Strangely that did not help to locate the faulty cap - if that was the
problem at all.

I started removing the caps from the board one by one and testing them
with
a multimeter but they all seemed OK except one that seemed to change the
capacitance slightly when warmed up. I replaced it with a new one (same
values, but higher temperature tolerance).
The cap was 6800uF rated at 25V and it was the biggest one on the board,
located near the amplifier IC.

Well the difference is that unlike before when the sound goes dead now, it
quickly comes back within a second or so. No need to even power down the
piano. But I still get the loud "pop" every now and then.

At this stage I am at loss as to what else I could try. Freezer spray
will
not help me now at all, since the problem goes away within seconds by
itself
(just to reappear a few minutes later)

Should I remove and test all caps? Seems like a lot of work with an
uncertain result.

I am hoping that someone with more experience (I am not a technician)
might
have some idea as to what may be causing the problem and how to proceed.

Thank you for any help you could offer. The piano is Yamaha Clavinova
CVP-85A and is way past the warranty.

Peter