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Messages - Joe

#76
Some ideas:

-Make sure no ground screws are missing, that go through tabs on the PCB. If they are all there, make sure they are tight.

-This is a pain, but remove the PCB and check the solder connections, especially on the jacks/pots. You'll have to remove the knobs and washers on all the pots first.

-Sometimes due to age etc corrosion forms around part legs, and sometimes you can even pull them straight out if it's real bad. Resolder bad joints if you find them.
#77
The docs now recommend a thermal shutdown switch on the heatsink. I mistakenly assumed that the diodes would behave as they do in a non-darlington output stage. I did find a thermal shutdown circuit consisting of a couple of transistors and a zener diode, which I'll try to figure out values for sometime. Not sure how to go about testing such a thing, though.

I've also added a diode clamp to the input to prevent overloading. (Obviously this will add distortion if the input goes past about a volt, but also limits the power output to a safe level.)

My goal was an easy build, not great quality. Hence the diode biasing (less to adjust) and output capacitor, etc. Thanks for the insights.