I recently acquired a non-working Sansui 7070 Receiver. The main
symptom is the speaker protection circuit is activated all the time.
This appears to be due to the presence of a high DC voltage at the
power amp output. Actually the neg. rail voltage (-42v) is present at
the output of BOTH channels. I checked the output transistors
expecting to find a couple shorted but they all check OK so I'm
thinking the problem is up the chain somewhere in the driver stage. It
seems odd though that the DC is present on both channels suggesting the
same part failed on both channels. Is it reasonable to think that
there may be a power supply problem since it is common to both
channels?

Any help/advice is greatly appreciated.