DECserver 700 PSU fix, H7881-AA

Adrian Graham binarydinosaurs at
Mon Feb 25 07:04:38 CST 2019

Hi folks,

My trusty DECserver has bitten the dust in a silent and non-violent way
with the fuse still intact so has anyone got tips on troubleshooting? I
know it's the PSU because I 'borrowed' another PSU from work and the unit
is running again. It's an ASTEC unit under the hood, and in my experience
of fixing the older types like the AC8151 (Memotech, TRS80 II/III, Osborne
etc) the chief culprits on an utterly dead PSU are the input caps and/or
the small 220uF or 330uF startup cap in the feedback circuit.

I haven't checked bitsavers etc for a schematic yet, does such a thing
exist? Helpfully the ASTEC board doesn't have a model number on it.


Owner of Binary Dinosaurs, the UK's biggest private home computer
t: @binarydinosaurs    f:

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