Adjustable voltage regulator for car alternator
 

On Apr 23, 7:52 pm, "Michael A. Terrell"
wrote:
John Popelish wrote:

Michael A. Terrell wrote:
John Popelish wrote:
What does this failure tell us about the PIV rating of the
trio? Not much, I think. You don't know that thew trio
failed from excessive voltage. Could have been a bond
failure that overheated one of them.

All three diodes were open.

So what do you conclude caused this failure, if anything?

I have no idea. All I found was four lugs and burnt plastic ash.
There was nothing left to do failure analysis on.

That rules out the simple bond opening failure. It could be a case of
run away overheating that eventually led to molten diodes. All diodes
will work as an incandescent LED for a while after which they usually
go open. This could be what happened to them.