Sony amp model:TA-AX285,year:1990 (guess),when the external tuner is plugged in (has special shaped plugs) the +12v shorts out of the 7812 three lead regulator I cannot isolate the problem to either tuner or amp I checked many components on both units.Anyone have any common repair tips?.Thanks in advance.
Sidney E-mail:sidneybek(at)yahoo.com Dartmouth,Nova Scotia Canada
If the voltage drops, and the regulator gets hot, but the input voltage to the regulator remains substantially the same, chances are that the problem is downstream of the regulator, in the tuner. If the voltage drops and the regulator stays cold, and the input voltage remains substantially the same, then the problem is likely the regulator itself. If the voltage drops, the regulator remains cold, and the input voltage also drops, then the problem is likely on the raw supply to the regulator, possibly an open circuit bridge diode, or a bad smoothing cap.
This is a bit of a generalisation, and needs to be tempered with experience, but should at least get you on the right track.
Arfa
need the schematic for the main board (the board with the outputs),I don't need the whole service manual as I am on slow diail up.Thanks in advance.
Sidney E-mail:sidneybek(at)yahoo.com Dartmouth,Nova Scotia Canada
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