[Info-vax] SBB power supplies failing slowly

[Scott Dorsey]

In article <t1rut2$uku$1 at gioia.aioe.org>,
Phillip Helbig (undress to reply) <helbig at asclothestro.multivax.de> wrote:
>I've seen this before, about a year ago, then it happened again in 
>another BA356: Disks go offline and into mount verification, then come 
>back after a minute or so.  The process repeats every ten minutes.  Of 
>course, being VMS, the cluster continues and practically nothing else is 
>affected, but it is annoying.
>
>Replacing the power supply solves the problem.
>
>I understand that a power supply can fail, but why is it failing in this 
>manner?  Maybe overheating and shutting off then coming back on?

Yes, the supply is likely crowbarring itself.  Replace all of the 
electrolytic capacitors on the secondary side of the board.  While you
are at it, you might pre-emptively replace the kickstart cap since they
are prone to fail in those cabinets.

>Now to find a few more replacement power supplies.  When collecting 
>SBBs, I concentrated on disks, and I think that I have enough of them.  
>Since the first power-supply failure wasn't until about a year ago, I 
>hadn't explicitly looked for them, but fortunately got a few with BA356 
>and other SBBs (mostly disks).

Just fix it.  No reason to replace the whole thing.
--scott

-- 
"C'est un Nagra. C'est suisse, et tres, tres precis."