Tom Lake wrote:
I have an ADM-3A dumb terminal and when I first turn it on the display
is squashed and the top line is mangled. After five minutes or so the
display looks OK but is a little jumpy. After a few more minutes, the
display is rock-solid and stays that way until the next time I turn it
on cold. If I turn it off back on, the display is still fine as long as
I don't let the ADM cool off first. Does anyone know what the problem
might be? What to look for?

The freezy spray comments are just going to waste your money. You are not
having intermittent problems when the unit heats up. Grab a heat gun and
hit the capacitors. If you have a kit of spares, just start to replace
them, or solder tack new ones across the bad ones and see which one fixes
the issue. I used to have an adm-5a, a very similar unit.

Here's a full manual, schematics start on page 57

https://www.manualslib.com/manual/10...ler-Adm-3.html

It's a great terminal, except for how that damn keyboard feels.