What is wrong with my amp? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 7 Old 06-14-2019, 09:41 AM - Thread Starter
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What is wrong with my amp?

I have a Sherbourne 5/1500 5 Channel amp that I purchased new 18 years ago. It has been a flawless performer in daily use for both music and HT without a single issue - until two days ago. In what I suspect is a bizarre coincidence, I was watching the Stanley Cup finals and at the exact moment the end of game horn sounded - and while the horn was playing - an incredibly loud static sound came pouring out of my speakers. Changing the volume had no impact on the static sound and it did not stop until I pulled the plug on the amp. The static sound returned when I plugged the amp back in. I know it has to be the amp because I replaced the amp with an extra 5-CH receiver I have and the system works without a static problem. Note that it was in one system for 14 years and then moved to a new system (new house) for 4 years -- and nothing has been changed in that system since its installation 4 years ago.

Can you help me diagnose the problem with my amp? I am pretty ignorant about how the electronics actually work. And I really don't want to pay to ship this behemoth off to some repair shop only to find its hopeless or too expensive to fix. If its dead, it served me well for almost two decades so I won't be too disappointed but I'd love to give it new life.

All suggestions welcome.

Thanks
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post #2 of 7 Old 06-14-2019, 10:03 AM
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Quote:
Originally Posted by DougF View Post
I have a Sherbourne 5/1500 5 Channel amp that I purchased new 18 years ago. It has been a flawless performer in daily use for both music and HT without a single issue - until two days ago. In what I suspect is a bizarre coincidence, I was watching the Stanley Cup finals and at the exact moment the end of game horn sounded - and while the horn was playing - an incredibly loud static sound came pouring out of my speakers. Changing the volume had no impact on the static sound and it did not stop until I pulled the plug on the amp. The static sound returned when I plugged the amp back in. I know it has to be the amp because I replaced the amp with an extra 5-CH receiver I have and the system works without a static problem. Note that it was in one system for 14 years and then moved to a new system (new house) for 4 years -- and nothing has been changed in that system since its installation 4 years ago.

Can you help me diagnose the problem with my amp? I am pretty ignorant about how the electronics actually work. And I really don't want to pay to ship this behemoth off to some repair shop only to find its hopeless or too expensive to fix. If its dead, it served me well for almost two decades so I won't be too disappointed but I'd love to give it new life.

All suggestions welcome.

Thanks
Most probability one or more capacitors possibly an output transistor.

The Sherbourn 5/1500 is built with component level parts as discrete mono block modules. It should not be difficult to repair. A local, experienced repair shop should be able to do the the work.

It's a good piece of equipment even though Sherbourn is no longer in business, I would have it repaired if it were me.
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post #3 of 7 Old 06-14-2019, 10:10 AM
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@DougF you must be a sharks fan too. My Integra 2 channel amp for zone 2 went out last week after the Blues defeated my Sharks.



All kidding aside....


1. take the speaker wire from the sherbourne and plug them all into the avr and bypass the amp and listen for static. if there is no static then its the amp.



2. plug the speaker wires back into the sherbourne, use the preouts from the avr back to the sherbourne left channel, turn everything on and listen for static. Turn it all off, then add the R channel and listen, turn it off and add the C channel and back on and listen for static. Continue to do that until you get all 5 channels going and can determine which channel causes the static.


If it is one channel, then create a new thread here with your issue, model of the sherbourne and your location and a member can probably help you find a local electronics repair shop.


good luck!
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post #4 of 7 Old 06-14-2019, 10:17 AM
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If it turns out to be caps, any thoughts on the lifespan of remaining caps? The underlying question here is should the OP consider replacing all caps at the same time if s/he likes the amp?

Seems like this would apply to other amps, too.

Just one more upgrade and things will be perfect.
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post #5 of 7 Old 06-14-2019, 12:06 PM
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Originally Posted by Bill-99 View Post
If it turns out to be caps, any thoughts on the lifespan of remaining caps? The underlying question here is should the OP consider replacing all caps at the same time if s/he likes the amp?

Seems like this would apply to other amps, too.

The OP indicated that it's 18 years old so yes, it's probably due for a re-cap. I would expect any competent repair shop to make that call after looking at it.

It's impossible to make that determination on the internet. Anything less than putting it on the bench is just a guess or speculation.
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post #6 of 7 Old 06-14-2019, 08:44 PM
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Very odd that the same problem would happen simultaneously on all channels, considering each channel has its own power supply. Perhaps there's a power-on muting circuit that's sending garbage to all channels?

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post #7 of 7 Old 06-15-2019, 06:00 AM
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Quote:
Originally Posted by Bill-99 View Post
If it turns out to be caps, any thoughts on the lifespan of remaining caps? The underlying question here is should the OP consider replacing all caps at the same time if s/he likes the amp?

Seems like this would apply to other amps, too.
There's one maxim that goes "if it ain't broke don't mend it" but I would say yes, replace them all as a matter of course. If that means a new power amp is cheaper...
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