polyex Posted March 11, 2017 Share Posted March 11, 2017 My model 4 screen is jittery. It jiggles and the size changes rapidly back and forth at times. Sometimes it is stable but for the most part it is not stable. I had an identical thing happen to me with a Wizard of Wor arcade machine. Turned out to be a sync problem with a bad transistor. Are the schematics to these Model 4 monitors around? Anyone know common failure points for sync problems? Regards, Adam Quote Link to comment Share on other sites More sharing options...
+arcadeshopper Posted March 13, 2017 Share Posted March 13, 2017 Yes have you tried Google? The Power supplies go bad and need to be rebuilt. Mine jitters every time you do a disk access. Sent from my LG-H830 using Tapatalk Quote Link to comment Share on other sites More sharing options...
polyex Posted March 13, 2017 Author Share Posted March 13, 2017 Yes, I did search Google. I found the TRS-80 Model 4 Technical Reference Manual. It has a chapter for it, but the pages on the video display are missing! Quote Link to comment Share on other sites More sharing options...
+arcadeshopper Posted March 16, 2017 Share Posted March 16, 2017 basically.. the power supplys are weak.. they get weaker with time.. they probably need new caps and so does the monitor chassis.. the flickering tends to happen during disk access which is the highest current draw my model 4 does this but it's tolerable so I haven't done the rebuild. Not sure if there are cap-kits to buy or if I have to just take it apart and make my own list. Also using modern lower power drives helps. Greg Quote Link to comment Share on other sites More sharing options...
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