> -----Original Message----- > From: cctalk [mailto:cctalk-boun...@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
