DEC BA11K Fan repair

Sue Skonetski Sue.Skonetski at
Sat Sep 26 15:34:23 CDT 2015

I know a few folks that custom make parts and many are from DEC if anyone needs me to check just let me know.


> On Sep 26, 2015, at 3:45 PM, Jon Elson <elson at> wrote:
> On 09/26/2015 11:25 AM, tony duell wrote:
>> I'll tell you one that you can't get -- the fan in the PDP11/44.
>> That one is a standard outer dimension alright, but electrically
>> it's plain odd. 35V 70Hz AC or something. It runs from a full-H
>> circuit from the (possibly battery packed) 36V supply. There have
>> been suggestions to kludge in 12V DC fans, but I would not do
>> that, the fan circuit _is_ part of the design of the PDP11/44 and
>> should be preserved.
> Oh, wow!  We had a 44 a LONG time ago, I never knew about that!
>> There is also the issue of keeping the machine as original as possible.
>> And the fact that a lot of the cheaper (i.e. $15) modern fans are very
>> poorly made. I think a rebuilt oriignal DEC fan would easily outlast one
>> of those.
> Well, fans come in many varieties.  There are Chinese knockoffs, and name-brand fans.  You can get plain sleeve bearings, "hydro-wave" bearings and ball bearings.  Good ball-bearing fans have a very long life, but may get a bit noisy near the end of their life.  These can also be re-bearing-ed quite easily, and it essentially makes them brand-new.  I've done this on my Dell desktop machines a few times. Yes, maybe the best fans do run over $15.
> Jon

Sue Skonetski

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