Help w/DEC H742 +15V...
derschjo at mail.msu.edu
Tue Apr 7 19:24:27 CDT 2009
So I'm now the proud father of a DEC PDP 11/40, which should be a fun
project/adventure to get running again.
I have been testing out the power supply and everything looked good this
morning, at which point I figured I'd populate the CPU backplane and see
what would happen. The answer is: not much -- occasionally a few LEDs
would light up, but the machine was completely unresponsive.
I went a bit further and tested the voltages at the backplane, and while
checking the +15V, my probe slipped momentarily, bumping a nearby
wirewrap pin, causing a small spark. Now, where I once had +15V, I have
0V. And since the -15V regulator is powered (in part) from the +15V
line, that's dead too.
I was hoping, after reading through the documents again, that it would
be something as simple as fuse F1 on the power control board, but no
such luck. The fuse is still good.
Any suggestions for what's most likely to have blown when I screwed up
here? Any recommendations for working on this supply? I'm really
looking forward to pulling this thing out of the rack to work on it --
this thing looks heavy :)
Josh (still slapping himself for screwing this up...)
More information about the cctalk