[no subject]

Those capacitors can be relatively bad and all it affects is more ripple 
on the DC feeding the switching transistors.  In the days of tube radios, 
bad filter capacitors would mean hum on the audio output, something one 
could generally live with.

But, the thing about switching supplies is that after the transformer, 
there are diodes that convert the high frequency AC to DC, and 
electrolyitic capacitors that filter out the high frequency AC ripple.

These filter capacitors operate at a much higher frequency, which means if 
they go bad, they will do a much worse job than if 60Hz was involved.  The 
higher frequency ripple that they have to deal with every day may also 
help to make them go bad.

Those filter capacitors after the transformer and diodes are doing much 
harder work than the high voltage capacitors on the AC side.

There's that big story of a whole batch of electrolytics that were bad, 
they may have kept working if they only had to deal with line frequencies. 
But instead, they end up venting, I have two computers I've dragged home 
with the top of the capacitors opened up, with dried electrolytic outside 
the capacitors.  Same with that Acer 19" monitor I brought home last 
year, It nominally worked (the baclklight worked, the logo appeared on 
screen, but sometimes I could feed it a VGA signal and it would display, 
other times it wouldn't, other times still the monitor kept recycling, 
going into standby then back to on).

I suddenly opened it up yesterday and there were clearly capacitors that
had vented.  I replaced them, it was just a few relatively low value 
electrolytics that were obviously filtering the DC output, put it back 
together, and it works fine.

    Michael

> Anyhow, should I just continue to replace the other electrolytic capacitors, 
> or is there something specific I can do to troubleshoot the problem? Are 
> there any other likely components likely to fail?
>
> I'll probably continue to replace the capacitors, but if anyone can offer a 
> better suggestion I'm all ears. I could replace the internals, but I'd really 
> like to get the original supply working again if possible.
>
> Any help would be most appreciated.
>
> -- 
>
> Cheers,
> Mike
>
> Find my Apple II projects online at:
> http://apple2.sytes.net/
>
>