PDP 11 gear finally moved

devin davison lyokoboy0 at gmail.com
Fri Jul 17 14:42:47 CDT 2015

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

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