DEC H745 regulator common failure modes?

Jon Elson elson at
Fri Nov 27 10:48:40 CST 2015

On 11/26/2015 11:13 PM, Pontus Pihlgren wrote:
> I can only say that they fail often. We have replaced lots in
> our 11/70. Luckily we have had spares.
> Sometimes the failure has been rather catastrofic with blown
> components. I think these modules run quite hot since
> discoloured pcb:s are common.
My experience with an 11/45 that ran 24/7 was the AMP 
Mate-n-Lok connectors would get a poor contact, heat up and 
go into thermal runaway, melting the plastic housing and 
totally frying the contacts.  I had to repair these at least 
5 times while we had that machine.  I never actually had a 
regulator itself go bad, it was always the contacts.  Maybe 
we just got lucky.  (This was also about 1977 - 1980, so 
parts have probably deteriorated a lot more since then.)


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