Well, the amp itself confirmed that the fault was internal a day or so ago - by blowing the output transistors and mains fuse!
The customer has since taken it back, as the repair bill would now be pretty high (he can get a good used one on eBay fairly inexpensively), so we may never know what the actual cause was.
My money is on one of the many diodes in the power amp section breaking down.
The mystery remains unsolved!
The customer has since taken it back, as the repair bill would now be pretty high (he can get a good used one on eBay fairly inexpensively), so we may never know what the actual cause was.
My money is on one of the many diodes in the power amp section breaking down.
The mystery remains unsolved!