On Fri, Apr 13, 2018 at 11:04 PM, Michał Pleban <lists@michau.name> wrote: > Hello! > > Mia Magnusson wrote: > >> Or you could repair the broken PSU. Unless a TDA1060 / NE 5560 or some >> replacement for the BUV48A/BUV47A power transistor is hard to get, >> there aren't any parts that's likely to be break and hard to get a hold >> of. >> I'd start with checking the electrolytic capacitors for short circuits. > > The problem is, I replaced all these capacitors a month ago, so it's not > likely that one of them failed. well, that can't be excluded anyway. I would not replace a non defective capacitor (I assume they weren't all faulty, were they?) Some switching mode regulators depend on the right range of the output capacitors ESR to be stable, though I think those old designs are not affected by this "problem". > > Nothing else in the PSU looks obviously broken or burnt, so I really > have no pointers where to look. I have never repaired a PSU before. first things: AC main bridge, the primary-side active devices (most of the times, two mosfets or two BJTs), the secondary side reference and feedback (usually an optocoupler) and the secondary side rectifiers. You can usually power the output with the same voltage supposed to be generated, with a current limited supply, AC disconnected, and look at the feedback signals, the voltage reference comparator and the PWM regulator in a safe way. Most of the times I get lucky by checking all discrete (diodes, BJTs) semiconductors with the diode check position on the multimeter and ESR of all electrolytics. HTH Frank >Received on 2018-04-14 00:00:42
Archive generated by hypermail 2.2.0.