Amp with dead channel only via tone controls - advice plea..

Archived from groups: rec.audio.tech (More info?)

Hi,

I have an oppotunity to get an amplifier that has a problem, and I'm
just trying to get a feel for how fixable it might be.
The amp is a fairly modern IC type device, made by Yamaha.

The problem is that the right channel drops out when the tone controls
are enagaged. If it is in 'Direct Mode' both channels are ok.

Any ideas on what this might be? Is it likely to be fixable by me?
(I'm practical but not an electronics engineer)

Archived from groups: rec.audio.tech (More info?)

In <K94ce.7395$YF5.5551@newsfe5-win.ntli.net>, on 04/28/05
at 11:54 AM, John Fryatt <jrf1@ntlworld.com> said:


>Hi,

>I have an oppotunity to get an amplifier that has a problem, and I'm
>just trying to get a feel for how fixable it might be.
>The amp is a fairly modern IC type device, made by Yamaha.

>The problem is that the right channel drops out when the tone controls
> are enagaged. If it is in 'Direct Mode' both channels are ok.

>Any ideas on what this might be? Is it likely to be fixable by me?
>(I'm practical but not an electronics engineer)

Typically, a "contact cleaner" (a chemical) will salvage the situation.

A few switches use closed construction and cannot be cleaned without
breaking them open -- but the sealed switches are not as prone to
developing this problem.

Not as likely, but there could also be a broken wire or printed circuit
trace.

A very thorough visual inspection is always helpful.


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