VT52 is back in service!
cz at alembic.crystel.com
Wed May 13 20:59:41 CDT 2020
Well, I put the VT52 back together, tightened all the bolts, plugged it
in, turned it on and enjoyed the silence. I can just barely hear the
transformer hum but that's about it.
Hooked it up to my PDT11/150, booted up RT11 and the display is
perfectly crisp and clear. Ran space invaders to check it out, no bugs
or errors and the screen updates perfectly.
Glad I got this working again. I'll take a look at that transistor, I'm
almost 100% positive the switching transistor is either leaking or going
bad. Either way I'll order a transistor when I have some time and put it
in eventually to see if it works. But to be honest the new regulator is
a thousand times better than the original discrete logic system.
So moral: If your VT52 goes nutty and the screen becomes a blur try
checking all of the voltages. An errant -12v will make the screen
unreadable at -15v and I'm guessing oddness on the other voltage levels
will do similar things as well. And don't leave it on for days, that's
probably what pushed the transistor over the edge, but I'm guessing it
has been crummy for awhile which is why I heard all that noise in the
high voltage circuit.
I feel like I accomplished something today. Thanks everyone for the help
and thoughts in getting this old girl to work again...
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