17 Jul
2015
17 Jul
'15
1:10 p.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of tony
duell
Sent: 17 July 2015 20:23
To: General Discussion: On-Topic and Off-Topic Posts
Subject: RE: PDP 11 gear finally moved
> When I repaired my VT100s I had to replace all the electrolytic caps
> on the monitor control board to cure the screen wobble. Before doing
> so I had reformed them all and I had tested them all for ESR and they
> had all tested fine so I was unable to determine which of them was the
> bad one. Perhaps there is other more professional test equipment I
> could use that would have helped, I don't know. I did keep all the
original caps
though (somewhere).
Are you saying that if you put any of the original capacitors back
(leaving new
ones in all other locations) you get screen wobble. If
so, I am not sure I
believe
you. It's been some years since I repaired a
VT100, but from what I
remember
there are plenty of capacitors that simply could not
cause screen wobble
no
matter what they were doing.
Or did you recap the board and find that it then worked. In which case (a)
perhaps only one of the capacitors was faulty or (b) it was actually a dry
joint.
-tony
=
I am saying that I recapped the entire board, so one or more of them must
have been bad. I agree it could have been a dry joint, but I am not going to
put them all back just to check :-) This happened on *two* of these boards,
so either I had two dry joints, or two bad caps.
Regards
Rob