the PV-1200 was blown
most obvious clue is the 100 ohm resistor at the output of
the front end 4560 opamp. It's burnt crisp.
can only come about when the amp is driven beyond it's limits.
It probably caused the pre-drivers to fail, thus triggering
a chain reaction. Driver's bases are pulled high, causing
them to blow. This in turn caused the bases of the power transistors
to go high, with catastrophic result on the power transistors.
so bad that even the DDT circuit is damaged. Note the two
burnt 1K ohm resistors at the DDT input. Since they are burnt,
we can infer that the associated opamp is gone as well.
it be repaired?
but is it worth it. A lot of man hours need to be expended,
meaning it's going to be expensive.
The underlying cause of this amp failure is not bad design
or manufacturing. Most likely, it's due to abuse or ignorance
of the user.
disappoints me though, is the way this amp fails. When it
does, it's total. Not good.