unibus backplane list?

Joe R. rigdonj at cfl.rr.com
Mon Aug 15 18:16:39 CDT 2005

At 02:31 PM 8/15/05 -0700, Dwight wrote:
>>From: "Joe R." <rigdonj at cfl.rr.com>
>>At 03:51 PM 8/12/05 -0600, you wrote:
>>>On 8/12/05, Brad Parker <brad at heeltoe.com> wrote:
>>>> Is there a list of the various pdp-11 unibus backplanes anywhere?
>>>I do not know of a master list online.
>>>> My 11/44 has a DD11-DF in it which is impossible to get cards into and
>>>> out of.  It's like something is physcally wrong with it.  Rather than
>>>> damage any cards I thought I'd replace it.
>>>It takes a bit of force to get hex cards in a nearly-unused backplane.
>>> I've bent latches trying to get boards in. 
>>   I've had similar trouble with the HP 1000 boards. I found that if I
>>clean the edge connectors and them wipe them with a rag slightly dampened
>>with WD-40 (mostly kerosene, a light oil) that the cards go in and out much
>>easier and I have a lot less intermitant contacts. I believe the oil
>>coating also helps reduce oxidation of the contacts.
>>  Joe
> From what I've been told, WD-40 contains both silicon and
>petrolium oils. I prefer using silicon grease for this purpose.
>Past experiments with petrolium oil and grease showed that the
>contact resistance increased on clean contacts while the
>silicon grease showed a significant drop in resistance.
> I recommend Dow-Cornings, DC-4.

   Does DC-4 lower the force required to insert and remove the board? Where
can you get it? Any idea how much WD-40 increases the contact resistance?
Even if it does increase the resistance it has cured many of problems that
I've had with the 1000s so it seems to do more good than harm.


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