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 Usenet: :+: ...!psuvax!mancuso Bitnet: :+: mancuso@psuvax1