HP-1000E PSU

From: Frank McConnell <fmc_at_reanimators.org>
Date: Mon Jun 19 09:57:28 2000

ard_at_p850ug1.demon.co.uk (Tony Duell) wrote:
> > > Looks like the installer is expected to adjust the power supply with it
> > > installed in the computer. Test points are on the crossover assembly
>
> HP were fond of suggesting that you do this :-(, even on machines where

Yes, this was not my idea. I spent some time staring at the manual
convincing myself that there were no directions for testing the power
supply with a less expensive load.

I suspect HP's thought was that they would probably have the service
contract, and if the power supply was going to fail in a way that
fried other stuff then it would have already fried the other stuff by
the time the service call was placed, and the CE would have those
boards in his kit too.

> Incidentally, am I the only person who finds the faultfinding flowcharts
> (like the ones that HP published in a lot of their service manuals) to be
> fairly useless? You know the ones that say
> 'Is there a clock at pin 3 of U5
> Yes : Is there a high level at ....
> No : Replace U5, X1, C1, C2 in order.'

It looks vaguely useful for people like me: a programmer with
soldering iron type who appears to have a read-only mind w/r/t the
more interesting bits of electronics. At least it would get me to a
board that I could then try to trace out and ask questions about.
That's why I pointed rdd through the first couple of bits -- they will
tell whether the power supply is alive at all and whether the
fundamental adjustment has any effect.

Unfortunately I don't think I have schematics for 1000s or 21MXs.
Well, not complete ones. Tonight I picked up the 21MX E-series
Installation and Service Manual instead of the 1000 E-series one.
Guess what, it's got appendices, including Appendix B with schematics
for the operator panel, 16K memory module, 8K memory module, and 4K
memory module. Not the power supply though. Hmm, on the other hand
I'm not sure it would matter, it looks like the power supply is
different in the 21MX -- instead of board with daughterboards, it's
got an upper and a lower board. Guess the difference is deeper than
the front panel silk-screening.

-Frank McConnell
Received on Mon Jun 19 2000 - 09:57:28 BST