IBM Monochrome "Black and White" Parallel card double image
ard at p850ug1.demon.co.uk
Wed Mar 24 15:55:15 CDT 2010
> I am working with an IBM Monochrome "Black and White" Parallel card that
> is showing a double image. I noticed that the 106 / 16+ tant cap at the
> top left near where C1 / U47 is printed was broken off the board so I
> put in a new one. There was no change. I tried another cap, no
> change. I removed the cap entirely, no change. I am looking for a
This is certainly not a capacitor problem...
I am working from memory (pardon the pun) and if necessary I can dig out
the schematics (they're in the Options and Adapters Techref).But I think
this board uses 2144s as the video memory (look for 18 pin DIL chips). My
expeirence is that that particular RAM has a record of unreliability, and
a missing adress line is just the sort of problem you get (and it would
cause the repeated image).
So my first guess is to replace the RAMs.
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