IBM Monochrome "Black and White" Parallel card double image

[Tony Duell]

> 
> 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 
> schematic/docs/suggestions.

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.

-tony