One more thing to fix... HP9000/380 power supply

Carlos E Murillo-Sanchez ce.murillosanchez at
Thu Feb 11 20:55:15 CST 2021

This decade seems to have increased the number of failing things in such 
a way that the "to be repaired" backlog is growing much faster than I 
can get to diminish it. Argh.  A month ago my trusty HP9000/380 ran just 
fine and I booted the different OS's in the SCSI and HPIB drives 
connected to it (this particular machine is interesting because the 
9000/300 port of NetBSD was partly developed in it: it was Mike 
Wolfson's). Yesterday, it failed to turn on; the power supply is dead.  
So I unracked the pile of drives and the computer, checked for obvious 
things (the fuse is fine, and nothing in the power supply is swelled up 
or leaking, or browned by heat; visually, it looks new; the HV caps seem 
to hold a charge).  I need the schematics for the power supply (at least 
the output connector; I can work my way back from that)  and also those 
for the backplane in this hp9000/380.  A preliminary search at bitsavers 
and elsewhere did not help.  Does anybody have these?

In the meantime, I finally improved the mainboard (had the parts for a 
long while) from a 380 to a 385 by changing the clock generator, and 
replacing the 68040RC25 with an RC33.

I ran this machine as a web server continuously for ten years in the 
2000's, totally exposed.  Many tried to hack it... and failed. Another 
personal connection to this architecture is that I used Apollos and 
hp9000/300 at UW-Madison back in 1989-91.  Boy, did I crunch numbers...


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