16 Jun
2009
16 Jun
'09
8:14 p.m.
Tony Duell wrote:
(yes, its three of them)
I'm sorry
for hi-jacking this topic but,
Most of the time it's just a bad contact at the wiper of the horizontal
hold preset inside.
Take off the terminal cover (extend the 'leg' all the way down, put the
terminal on it's screen, take off the 3 (?) plastic caps and undo the
screws under them).
(VT220s have a common fault that takes out
horizontal hold)
I think my VT220 has this problem, is there any documentation regarding
diagnosing and fixing this problem? I have search to no avail.
The horizontal hold preset is marked on the paper
cover on the video PCB.
Note its position, then turn it several times from one end to the other.
Put it back to the original position.
I could not find a paper cover, but it is printed on the PCB.
Plug the terminal into the mains and power up (you
don't need a
keyboard). If the picture locks, power down amd put the cover on. If not,
turn the horizotnal hold preset until it does, and set it to the middle
of the range where the picture is locked. Power down, wait a bit, power
up nd check it locks. Then power down again and put the cover on.
If you can't get the picture to lock by adjusting the preset, then you
have a more tricky fault to find :-)
-tony
My memory served me wrong, or I read the post to fast. Is the symptoms
of a "lost" horizontal hold that the picture will scroll, looping around?
This vt220 in front of me has no picture at all. I was using it and
between the blink of my eyes the picture disappeared, no bang, no smoke,
just gone. I think the logic still works, judging by the led indicators
on the keyboard and the satisfying beep it "boots" just fine.
Any ideas where I should start looking?
Kind regards,
Pontus.