Sent a few days ago, but it never appeared on the list:
You don't bother to test, you just replace all of the shiny silvery
capacitors. They are the ones that don't have stripes on them : )>
IMHO, your amp was likely in this condition before you plugged it in,
you plugging in the wrong impedance speakers didn't matter at all...
Swapping out expired components is a big thing in the guitar amplifier
world, so you might take it by your local amplifier repair guy. I am in
Austin, so perhaps not typical, but there are three within about ten
minutes from me. Walk in, ask him if he can replace the leaky caps and
put the circuit diagram in front of him, and see what he says...
Old guitar amps are worth a fortune, but they all need this type of
updating, so there is a business in doing this. It is interesting to me
that this guy is doing it with classic audio amps. Like this guy,
people sell kits of the parts needed to refresh a specific Fender. Of
course, in that world distortion is a good thing, but the approach is
the same.
The issue is that this can only be done with components of a certain
age, specifically, before circuit board manufacturing advances made the
circuitry too small for our fat fingers to work. Your amp might be too
modern and miniaturized... If you are committed to a high end solution,
as you were when you bought the thing 20 or 30 years ago, then I think
the guy's trade-in makes sense. If you are just looking for music for
the shop, and only are dealing with this because this box happened to be
on the shelf, I would suggest a boom-box from a garage sale. In fact, I
will swap you a big old boom box for your dead amp, how about it?
Since we are on shop-talk, I was pleased to find a guy back in the early
nineties who was doing this cap refreshing service for the fuel
injection circuit board for my '75 450SEL...
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