[Kenwood] PS-53 on strike

[Peter Ravn]

Without warning my otherwise reliable PS-53 died the other day: no 13.8 V on the output terminals. The fuse was ok, so the board was inspected. Q5 (2SC2458) sitting close to thermistor TH1 seemed to have melted and fused with TH1, which was covered with sticky white powder. Further inspection and internet research proved that Q5 and TH1 are covered with a piece of shrink tubing to keep them in close contact with one another. I replaced the transistor and cleaned and checked the thermistor, which measured 2.4 KOHM with falling resistance by increasing temperature.

Still no voltage on the output terminals. But when the power switch is turned and off,  there are 19 V on the terminals falling slowly to zero, which might give the experts on this thread an idea where the fault is.

Thanks in advance
OZ8CTH
Peter