[sdiy] Weird Ripple Voltage

[mike ruberto]

Hi René,

Ok I will give this a shot. Although, I don't see any evidence of it
at all on the other rail which has the same circuit coming off a
separate winding on the transformer.

Is there any reason not to replace these snubbers with metalized poly
instead of ceramic disc?

Thanks

Mike

On Fri, Apr 4, 2008 at 11:06 PM, René Schmitz <uzs159 at uni-bonn.de> wrote:
> Hi Mike,
>
>  mike ruberto schrieb:
>
>
>
> > 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?
> >
>
>  That could be a resonance from the caps and the inductance of the
> transformer. I'd try to see if changing the snubbers capacitance makes a
> difference in frequency of that ripple.
>
>  Cheers,
>   René
>
>