Bose Panaray digital system controller psu

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The Bose Panaray System Digital Controller model Bose-01 was not switching on. The unit has NE5532 for the analog audio signals. The PSU has four outputs. 3.3, 5.0, +15, -15 volts.

Fault... the mosfet K1402 has shorted.

The psu is an SMPS, but for regulating +/-15 volts, it has 7812/7912.
It could have used so many other options instead of these fixed voltage regulators, but that is Bose. Forget this part but why does the psu has these regulators when the smps can be designed to do it without these. Is there any specific reason, related to audio or is it just easy/convenient.

Gajanan Phadte
 
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