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

Paul Berger phb.hfx at
Thu Feb 11 22:12:44 CST 2021

On 2021-02-11 10:55 p.m., Carlos E Murillo-Sanchez via cctalk wrote:
> 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...
> carlos.
I have never seen any schematics for this power supply however on 
bitsavers there is a document related to the expander that shows the 
power supply pinout. 
This would be the same power supply as the processor box. Also


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