[jakdedert]

David Nebenzahl wrote:
snip

The unit has only one fuse, which is good, on the primary side of the
power transformer. Someone else pointed out that there may be fusible
resistors in the output stage: these appear to be present, biggish
ceramic-packaged resistors very close to the output transistors. Maybe
these are open. Kinda hard to test w/o a schematic, as the resistors are
in packages with multiple leads.

It's looking like the parts bin for this guy.


You've done a lot of messing around, but it seems you've yet to
systematically test the unit from front to back...or even from back to
front. Either can be a valid method, although conventional wisdom is to
start at the input and trace signal forward through the circuit.

In your case, I'd at least test the outputs, as suggested many times in
the thread. Inject a signal--it could be anything, like the output of a
DVD player--into the output section. If you get sound out, then the
problem is before there...the preamp, or its switching.

If not, the outputs could be blown, although it's not the only
possibility. The protection circuit is the other main potential
culprit. Output devices (I believe you said they were discrete) are
usually easy to check with a DMM.

Test the preamp by plugging another amplifier into the tape outs with
the tuner selected as source. 'Another amplifier' could be one cheap
powered computer speaker, with appropriate 3.5 mm RCA adapter...or it
could be another working hifi amp. The same computer speaker can be
used as a signal tracer to track the signal through the entire circuit,
with a suitable probe (consisting of a tinned bare wire and an alligator
clip for ground.

In any case, what good is a parts bin with suspect parts in it? If
you're really determined to ditch it, just do so; but you've gotten a
lot of advice that you've apparently not followed.

jak