On Sun, 17 Aug 2008 19:59:52 -0700 (PDT), put
finger to keyboard and composed:

It stands to reason that rotating the pot fully CCW or CW should not
damage the amp, otherwise not many would have left the factory. If the
trimmer is wired as below, then why not measure the idling
voltage/current at both extremities and verify whether this trips the
relay?

* |---|
* | * |
* | * V
--|-/\/\/\/\/\---

If neither setting causes the relay to trip, then the problem must lie
elsewhere.

- Franc Zabkar

Running it at a higher voltage for the idling current does get it to
run hotter. Could the protection be a thermal issue?

If I'm visualising the circuit correctly, then at 30mV the idling
current would be 30mV/0.47R = 60mA. If the supply rails are +/-40V,
then the dissipation in the output transistors would be 80 x 0.06 =
4.8W. At 7.5mV the dissipation would be only 1.2W. I can't imagine
either of these figures would give rise to thermal problems.

- Franc Zabkar
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