Steve Thompson wrote:
>> I have checked everything else in the PS, and the common
>> denominator seems to be the cap bank. Am I missing something?
> Fuses between the transformer secondary and the bridge :-)
> To kill diodes in that way, you've got to be looking at something
> approaching a short - it's hard to see how loose screws would
> cause that. Open cct bleeder resistor(s) might, if one cap arcing
> led to over voltage on another and so on.
> Another thing to check is the insulation between secondary and
> core on the transformer. If one end arcs to the core you can end
> up with one leg of the bridge 'shorting' out the secondary. If
> that's happening, then I think your damaged diodes will always be
> in the legs feeding the -ve end of the caps.
I have been puzzling over this, I think it is either something that is not
on the schematic (like
a terminal strip or mounting screw arcing) or the secondary winding is arcing
to something, you need
to "hi-pot" the transformer's secondary winding to the frame and the primary
winding/s for 10 or 12
kV before you cook more diodes.
--
Ron KA4INM - A city is a large community where people
are lonesome together -- Herbert Prochnow
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