11/73 (ba23) bringup after 12 years in deplorable storage conditions

Jacob Ritorto jacob.ritorto at gmail.com
Thu Nov 20 19:09:28 CST 2014

  OK, decided to let the machine acclimate from 25 F to inside-house temps
overnight.  The thing's still all together - RD54, TK50 with a tape in it
(!), Ethernet, DZ interfaces and TK25 interface plugs on rear.

  Guess I'll be conservative, empty out the backplane and do the careful
powerup first.  So where would I put the resistors?  I still have my
wirewrap tool somewhere around here. Could try to figure out what pin is
the 5v rail and tie in a resistor on there, I guess.  But I'd rather not
tear the thing apart *quite* so much if I could avoid it.  Is there a way
to check ripple w/o a scope?  (don't have one)


On Thu, Nov 20, 2014 at 4:38 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu>

>     > Roe Peterson roeapeterson at gmail.com
>     > I would remove all the boards, blow it out, insert the minimum board
>     > set, (CPU, memory, DL console, maybe bus terminator depending on
>     > backplane) and just turn it on.
> That long in storage, I think that I'd probably go for powering it on with
> a
> dummy load first. It's not _that_ much more work, and it could save some
> expensive/rare electronics.
> It you don't have any QBUS Minimum Load Modules, get a couple of
> high-wattage
> resistors (down at Radio Slack, if necessary) and rig the equivalent. The
> M7556 MLM draws 1A of +5V, and I like to run two for testing. RS sells
> 10-Ohm/10-W resistors (ISTR they had smaller ones too, but I needed to
> test a
> 12V supply, hence the 10-W), so buy four...
> Probably a good idea to throw a 'scope on the DC power, too, check for
> ripple, etc.
>         Noel

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