Don T wrote:Ok, what kind of trimpots are installed in the the thing? I've honestly never seen any that look like that.
I've learned to never assume anything, therefore: Check for AC voltage across the two green wires coming from the transformer. Then check for DC voltage at the Anode end of CR15 or CR16 (which should be negative), and at the Cathode end of CR18 or CR17 (which should be positive)
It may be worth replacing CR19, it's a 1N4748A zener diode, 22V, 1W. Zeners are a PITA to test.
Take Q7, Q6, and Q5 off the board and test them out of circuit. Be sure to also check them "backwards" for leakage using the diode test function on your DMM.
Let us know how those turn out! Good Luck!
garranimal wrote:What kind of problem is it? Voltage too high/low? Is this in disconnected state or under load? This is a case I would audit all currents going in (from AC) and the sum of all currents going out of the power supply. It should lead you to the cause pretty quick.
I had such problems under load with an old stringer. After the current evaluations I discovered the problem to not be on the power supply board at all. A transistor down circuit had blown and was drawing too much current from the PS.
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