[rescue] SPARCserver power supply

Lex Landa brooknet at imap.cc
Sun Dec 19 12:09:31 CST 2010

The 630MP power supply saga continues!

Having run continuity checks on my 630MP's lines, I've verified that my
original pinouts were correct (touch wood) - but some damage occurred
when I first powered up the replacement power supply, and I found that a
capacitor (C55) on the backplane had blown; this caused damage to the
RAM chips of the cgthree card and it now shows a corrupted screen.

Could any electronics experts please make a guess at what could have
caused this?  A guess: something similar happened with my Apple II; I
used a replacement PSU there too, and the RAM chips required the -5V
line to be active before the rest of the lines.  When I used a new PSU,
the -5V line powered-up at the same time as the other lines, causing the
RAM to eventually fail.  In that case, the chips didn't short-out, but
just died.  I'm wondering whether the SPARCserver issue is related or
whether this is a case of 'silicon latch-up'.

Thanks to Simon for the VMEbus connections.


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