[sdiy] Weird Ripple Voltage

[mike ruberto]

More strange power supply problems. This time I have a high pitched
whining in the audio. I traced it back to the devices power supply
where it seems to be originating before the regulator. On the scope I
see a ripple voltage with the usual saw shape but it is shot through
with  lines. Increasing the volts division I can make out a tiny
sawtooth wave riding on the ripple at several times the ripple
frequency.

I disconnected the regulator to verify the origin and sure enough it
coming form the rectifier/filter stage. That stage is a bridge
rectifier with a ring of snubber caps and then the main filter cap and
another 0.1uF cap. Am I looking at a problem with the bridge rectifier
or is one of the snubbers bad?

Mike