an ADM-3A cam in tod...ay

Jules Richardson julesrichardsonuk at
Thu Dec 28 08:26:57 CST 2006

Alexandre Souza wrote:
>>> Replacing the CRT would be preferable, but only in the case of 
>>> dealing with
>>> somewhat standard gear. Every piece of gear I have that has the dreaded
>>> screen mold, replacing the crt is not likely as the crt is somewhat
>>> oddball/nonstandard. Not something you can just order up. I will be 
>>> giving
>>> the faceplate removal thing a try when I get to that DG terminal for 
>>> sure.
>    I'm yet to see some "oddball" tube into a monitor. I use to replace 
> them here in Brazil with old mono VGA tubes.

At least in the case of the HP250 one, the aspect ratio of the CRT is around 
2:1 (unlike most screens which are closer to 4:3). I'm surprised if HP got a 
CRT custom-built just for them, but maybe that was the case; certainly I've 
seen nothing like it in any other displays ever.

Mac portrait displays are presumably similarly difficult to get replacement 
CRTs for, at least without realigning the yoke (I gather that most CRTs don't 
like a change in orientation, although I used to run a Sun colour display on 
its side a few years ago with no obvious ill-effects)

For more conventional equipment I suspect that a swap is possible, providing 
knowledge of how to tweak the old circuits with the new tube is known.



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