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[TASS] A Fix At Last!



Some of you may recall that I had a temperature related intermittent in the
RA drive.  I eventually traced it down to missing pull up on a 7403.  The
RA drive has been driving me mad.  TOM up on the roof has continued to have
a temperature related RA problem.  I would go up and look on the back of
the board to make sure I had installed the pull ups.  Yep, they were there.
 This problem continues to mess up images since sometimes the RA drive
skips and that causes improper RA motion.  A couple of days ago, it got
cold enough that TOM would simply not run.

Today, I set up a system on the bench and with my new oscilloscope put test
points on everything and set out to make it work.  I pulled a board from
the stack that did not have the pull ups, and as soon as I put the cold
spray near the RA circuits, it quit working.  I added the pull ups and it
was solid.  So why would the board on the roof quit?

Well, I went up and got it.  Sure enough, there were the pull ups.  But I
had just soldered on a set and these did not look right.  Soon I realized
that I had put them on the wrong IC.  Sigh!

Things are now back together and running the RA exercise program and all
seems well.
I should take a tip from Santa.  Santa checks his lists twice!

OK, all this has been mostly due to me working myself into a snit.  I did
not even get much done.  But that is always the case.  You can just work so
hard, and then it is a net loss.  Still, there is a lot done.  ARNE is
sitting here complete.  MICHAEL is nearly complete.  There is still a lot
of testing to do on both, but if I go at a measured pace, I will get it
done.

Tom Droege