TRS-80 Mod I Video Displayu

I have the service manual for the original (no green filter, controls in a horizontal row at the bottom right) somewhere, and I'll dig it out if you want to get inside. However, a word of warning. This is by far the most unpleasant monitor I've ever worked on. It's a converted RCA portable TV (the conversion consisted of removing the tuners and IF plug-in PCB and fitting a video input PCB in the IF PCB slot). This means that the 110V model is hot chassis -- the video input PCB contains an optoisolator so the computer is not directly connected to the mains. Since you need to work on the vertical deflection circuit, you'll be working on the 'hot' part. If you don't have an isolating transformer then don't even think about working inside this monitor with the power applied! The 230V model is a bit more pleasant. The TV's PSU was strictly 110V only, so it needs a transformer for 230V mains. Radio Shack used a proper double-wound isolating transformer, which means the chassis of the 230V model is isolated from the mains. The video input board on that model is just a transistor buffer stage, no optoisolator. Let me know if you want me to dig out the service manual and talk you through the vertical deflection circuit. -tony