Bob Simon wrote:
> I have a McIntosh 2100 that was performance certified in 1976 at a
> clinic. Now it needs service - one of the channels intermittently
> drops.
>
> Do they still have those free clinics?
In response to Mark Z's reply. Sometimes the card edge connectors of
the driver boards can also cause noise. They can be cleaned, but
getting to them is not a task for someone who does not feel comfortable
doing serious repairs, as a lot of the amp has to come apart. (DON'T use
any abrasives on the contacts, just lacquer thinner on a swab will do,
clean ONLY the card edge, not the socket on the chassis. Work the card
in and out of the socket a few times to wipe the contacts.)
I've also seen the input differential transistors get noisy, and these
should be well matched if replaced. They are much more likely to cause
a noise problem than the output transistors. a few other parts on the
driver boards can also cause problems. Ask the repair shop if they can
gain match (beta match) transistors. If they seem to have no idea of
what you are talking about, take the amp elsewhere. If there is ANY
significant DC at the terminals (I'd say more than 10 mV) then the amp
needs service. Also, one channel running considerably hotter than the
other is reason for concern. The amp should be a bit warm after an hour
or 2 with no signal, but not hot.
Sending it to McIntosh is certainly a safe choice, but ****pping could
be expensive depending where you are. You might want to look at the
McIntosh web site for an authorized servicer in your area.
Regards,
Tim Schwartz
Bristol Electronics
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