20 Jun
2009
20 Jun
'09
10:34 p.m.
----- Original Message -----
From: "Josh Dersch" <derschjo at mail.msu.edu>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Saturday, June 20, 2009 12:13 AM
Subject: Service Manual for Ball TV-90 monitor?
Decided to dig out my IBM 5120 and try to get its
monitor working, at long
last. It's a Ball TV-90. Anyone out there have the service manual for
this? (Worst case, there's a copy on eBay right now, but before I go
through that I thought I'd bug you guys...)
I mentioned this issue a few years ago, here's a photo of the interesting
distortion I'm getting: http://yahozna.dyndns.org/scratch/5120disp.jpg.
Thus far I've done a complete cap kit with no effect. I hate working on
monitors, but I really want to get this running again...
Thanks,
Josh
Is that display by any chance supposed to be 40 characters wide rather than
80? ISTR the 5120 has a 40-wide video mode. The reason I ask is that the
best I can tell from the picture the display is exactly 40 characters wide
with the characters brighter starting at about the 10th character through
the 20th character on each line. If that is correct then I'd think the
problem is possibly with the grid-1 or cathode circuitry, in the sense that
something is driving grid-1 somewhat more positive or the cathode more
negative in sync with the horizontal sweep. But of course ICBW...
Later,
Charlie Carothers
--
My email address is csquared3 at tx dot rr dot com
