# Crackling and Hissing Yamaha

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#### Jeffrey Landgraf

Jan 1, 1970
0
Gentlemen,

My Yamaha P2100 stereo amplifier has "crackling" and hissing on a single
channel. It started out intermitant and would disapear (for awhile) when
the amp was turned off and then back on immediatley. The audio from that
channel is very thin sounding as well. I've replaced all the electrolytic
caps awhile back and the problem remains. I'm an experienced board level
trouble shooter but I'm trying to cut the time for diagnosis to a minimum.
In my experience "thin" is often dried out caps but this amp design does not
use many electrolytics ( and they've been replaced!). I've not fixed an amp
with crackling and hissing. Any ideas on which components would likely
cause these symptoms?

S

#### Sofie

Jan 1, 1970
0
Jeffrey Landgraf:
I think you should be concentrating on looking for cracked, cold, or
otherwise faulty solder connections on the main circuit board, especially
near and around the high heat producing parts such as power semiconductors,
diodes, resistors, etc. Re-solder as needed.
Very IMPORTANT..... you would be best advised to STOP using your amp until
you get this fixed, either by you or by a service shop. If you continue to
try to use the amp with this problem you risk additional and major (read
EXPENSIVE \$) failures.

J

#### Jeffrey Landgraf

Jan 1, 1970
0
Daniel,

I've got the amp on the bench and in fact did stop using it. I've repaired
flamed amps before and it's defiantly not fun! It's always easier to fix an
amp that is "sort of working" than one that's gone to pasture. Resolder is
a simple, good idea and can't hurt. I'll do that first.

Thanks,
Jeff

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#### Bill Webb

Jan 1, 1970
0
Agreed. I had almost identical symptoms on a Sony amp (loud SNAP! from
center channel at power-on, intermittent audio with sputtering and
hissing "wet candle" sound) which resulted from cold/cracked-off solder
joints on an amplifier IC at the center (surround) channel output.

Sorry to post a "me too", but watch those little STKs or integrated
amplifiers (if any), even if they don't look like the "usual suspects"
for bad solder joints (large pins, high heat, bolted to chassis or
flex-prone heatsink, etc.)

Jeffrey Landgraf:
I think you should be concentrating on looking for cracked, cold, or
otherwise faulty solder connections on the main circuit board, especially
[snip]

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