mancuso@psuvax.UUCP (04/05/84)
If you have gotten the power connected to your 820 and hooked up
a video monitor to the HS VS and VO pins on J7, you may have no-
ticed that only the left half of the screen shows, and the right
half seems to run off the right edge of the screen. You are not
alone. I got my board up a couple of days ago, and I thought
that the problem was caused by the circuitry that I was using to
get composite video. After a couple of hours of dedicated (?)
work with an oscilliscope here at the computer lab, ace video
wizard Ralph Droms found that the horizontal sync signal that is
available at J7 was much too long. Somewhere between J7 and where
it is generated, the signal gets perverted, and it kills half of
the screen. Ralph located a more reasonable signal to use for
the HS, and it works beautifully. To use this new and improved
HS signal, forget about pin 4 on J7 and use pin 8 on U34 instead.
We found this error on both of our boards, so there is a good
chance that it is on all of them. Please let me know if this is
the case.
Happy Video!
---
Overall there is a smell of fried onions. (fnord)
:+: Pat Mancuso
:+: Penn State University
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