Just in case someone out there other than myself dares to take on these,
and any ideas. All the previous times as far as the PAs are concerned
just matter of replacing SMD fusible resitors and powerFETs. This time
done that but unit goes into protect mode. With known good PA only or no
PA in there, then no flashing green power LED = protect mode.
I bench test these little 2 ounce, 250W, "digital" PAs as far as
quiesence is concerned and with +/-30V supply rails , sits there happily
with normal , for this minimal test, 0.7mA balanced current draw.
Cold testing DVM-D fashion has shown up no difference to the known good
PA SMDs.
I suspect something in the protect monitoring part of the pa has gone
wrong at the original failure but its a workup to make extenders etc to
probe these amps in full live circuit. At least the schematics etc are
out there for these amps.