Hello
After reading a little on this forum I decided to dig out my old TRS-80 Model 1 to see if it stll works. As you'll see in the photo, it boots and runs BASIC code. However the display is distorted. The vertical is very stable and I can adjust it as you would expect using the various pots. The horizontal is wobbly and characters which should line above each other vertically are not vertical. The knob on the back of the display is very sensitive, moving it just a tiny bit messes up the display badly. The horizontal positioning pot inside the keyboard seems to have no effect at all. I have checked the Sync Generator circuits within the keyboard unit with an oscilloscope and they seem to be working fine. Therefore I'm suspecting the display circuitry. I know very little about how CRTs work. Any advice on where to start?
After reading a little on this forum I decided to dig out my old TRS-80 Model 1 to see if it stll works. As you'll see in the photo, it boots and runs BASIC code. However the display is distorted. The vertical is very stable and I can adjust it as you would expect using the various pots. The horizontal is wobbly and characters which should line above each other vertically are not vertical. The knob on the back of the display is very sensitive, moving it just a tiny bit messes up the display badly. The horizontal positioning pot inside the keyboard seems to have no effect at all. I have checked the Sync Generator circuits within the keyboard unit with an oscilloscope and they seem to be working fine. Therefore I'm suspecting the display circuitry. I know very little about how CRTs work. Any advice on where to start?