17 Jul
2015
17 Jul
'15
12:42 p.m.
Thank you for the detailed information. I need to figure out how im going
to get it out of the rack and moved to a place where i can test it over the
next couple days where it will not be in the way. Ill find some way to do
a dummy load and do an extended test to be sure the supply is working
properly. All fingers crossed, god it better not have damaged any of the
boards, i do not know where i would get replacements.It took years for me
to get the machine, who knows how long it would take to find a specific
board that is bad. I did buy an oscillicope and a logic analyzer well in
advance in preparation for getting this machine, however short of pressing
the power button no clue how to use them or basic troubleshooting
procedures. Guess i just have to learn by doing....
On Fri, Jul 17, 2015 at 3:23 PM, tony duell <ard at p850ug1.demon.co.uk> wrote:
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