On 7/12/23 16:36, Santo Nucifora wrote: > I am trying to fix a Commodore PET Educator 64 model that has video > issues. There is no schematic that I could find for the board marked > with a part number of "02-96409 REV 3". Would anyone have a schematic > for it? > > Here is a picture, if it helps: > https://vintagecomputer.ca/wp-content/uploads/2023/07/Educator64-02-96409Rev3-videoboard-scaled.jpg <https://vintagecomputer.ca/wp-content/uploads/2023/07/Educator64-02-96409Rev3-videoboard-scaled.jpg> > > From my understanding, the monitor in the Educator 64 allows for shades > of grey (or green in this case) and is not a standard PET monitor so it > may be specific to the Educator 64 only. This monitor will run with > signals from an unmodified C64 motherboard. The PET 64, however, has > extra circuitry on a small daughterboard that changes the video signal > to black and white so that a normal PET monitor will work. > > I currently have vertical collapse on this particular monitor. The video > output of the C64 via an external monitor is good so the signal should > be good as well. Having a schematic would help with diagnosing the > vertical circuit. Can't help you with the schematic, but the TDA1170 is the IC that controls the vertical deflection and a datasheet is easily available. The TDA1180 is for the horizontal part. You might also want to check the socketed NE556 on the left side. Sockets can develop contact problems over time and this doesn't look like a quality socket. Same goes for all the potentiometers and that little switch. GerritReceived on 2023-07-12 18:00:08
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