switching power supply

Mainly capacitors. Could be a zener diode or something in the feedback, like a TL431 voltage reference or a problem in a voltage divider. Lots of other possibilities, though, and the more complicated the supply, obviously the more potential suspects.

Mark Z.

Make sure you have a load on the main (regulated) output!

See the SMPS repair guide at the site below.

--- sam | Sci.Electronics.Repair FAQ:

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