I know very little about home stereo equpiment, but I just got this
tuner from my father. I hooked my electric violin up to in (via the
Phono input, guessing that that would provide better amplification)
and everything was fine and good.

Then, the other day, I was playing "Cluck Old Hen", with the volume a
little louder than normal. Perhaps a heard a soft "pop", but perhaps
not... certainly there was no more sound from the speakers.

The odd thing is that everything seems to be working fine--the unit
powers on, the LCD display works perfect, but none of the
speaker-related buttons do anything (I can't adjust the loudness, turn
on Dolby, set the EQ). The rest of the buttons behave as before. Also,
before, the LCD display would show the levels even without speakers,
but now it does not.

Finally, there was a little glowing red light on the volume knob. This
light is no longer on.

From all of this I'm certain that someone who knows more about home
audio equipment should be able to diagnose the problem pretty quickly
and help me set it right. I checked all over for a fuse, or a reset
switch, but couldn't find anything.

Hey:

You'll want to check a few things, and the probably post back to get more info.

It sounds like the most likely culprit is that your e-violin (was it a
pickup or a true electric violin like a zeta etc?).  Very likely your
electric violin produces more current than the input was expecting
(phono expects very little - which is why you frequently seem to be
getting more volume than you did when put it into another input).

Check the following:

1.) make sure your tape monitor switch is the correct position.  Not
likely this, but gotta check it!

2.) Do you have a jumper cable running between you "pre out" and your
"main in" on the back?  If not, this is your problem.  Its unlikely
that this is it, since it would not have worked in the first place
without the jumper unless plugged into an external amplifer.

Those are the most likely super-easy-to-fix problems.  On to the next
round if no fix there.

3.) Check to see if you get sound through headphones.  A yes or a no
will help locate the problem at a particular junction in the
circuitry.  If you don't here anything in the headphones, crank up the
volume and see if you hear a faint version of what you're expecting to
here (do this with a CD or something that is not your violin :)  )

4.) Do you hear a click right after turning it on and then another one
about 2 seconds later?

5.) There are three fuses in your Technics unit.  Check them all! 
They are located right next to the power supply on your unit - all
fuses in the unit are right there.  Unfortunately, technics at this
time used in-house fuses and i don't think they are as cheap as a fuse
ought to be.

You'll want to have blown a fuse, prefer to have not destroyed a input
or output.  All of these are possible!

Regards,

Ben

Ben--
Thanks for taking the time to help me out here.

1) I've been mostly playing with "tape Monitor" off--that is, no "tape
monitor" icon visible. I tried changing the status back and forth (and
playing a cassette tape, as well) but no luck, no change.

2) The jumper is, indeed, in place.

3) No sound through the headphones. I would have been surprised if
there had been, because before (even with head phones) the main LCD
display showed the current levels, and there is no activity there now.
Also, there was a light on the volume knob, previously.

4) There is, indeed, a distinct click, followed two seconds later by
another one. Is that a good sign? (:

5) This is what I was hoping for, as well. After I posted the above, I
found one fuse, and took it to Radio Shack. The people there (who were
not, frankly, the most competent) concluded that it was blown and sold
me a pack of new fuses. I installed the new fuse, but there was no
change in the behavior of the tuner.

a) Is it still possible to buy Technics in-house fuses? Maybe the fuse
that Radio Shack sold me simply will not work in my unit, and that's
that.

b) Three fuses you say? I can only find one. I've posted a photo of
the unit, open, with a circle around the only fuse I could find:
http://flickr.com/photo_zoom.gne?id=18209201&size=o

Any advice about where the other two might be hidden?

Thanks again for the advice!

-=Benjamin