SuperSVGA
Well-known member
I have a Macintosh Classic II (Performa 200) on which vertical deflection was not working. All I got was the bright horizontal line.
After replacing nearly all the electrolytic caps, the video/power ICs, and testing a few diodes, I was still getting the exact same symptoms.
When I checked voltages at the TEA2037, I was getting very low voltages at the Flyback Generator Supply (0.48V) and Frame Power Supply (0.32V).
I tested RL2 which tested to be around 650KΩ, which according to the markings should only be 1Ω. I replaced it with a 1Ω 1/8W metal film resistor and put it back together. Notably, the Bomarc schematic I found online for the Classic I lists RL2 as 2.2Ω, but the markings on this one were clearly 1Ω.
Now when I test it, I get "full" vertical deflection but the picture is unstable, jittering/scrolling vertically.
Turning the vertical size adjustment, I can only get a stable image by vertically squishing it down to half of it's size.
Any idea what's wrong now? I've replaced so many parts in this I'm not sure where to look next.
After replacing nearly all the electrolytic caps, the video/power ICs, and testing a few diodes, I was still getting the exact same symptoms.
When I checked voltages at the TEA2037, I was getting very low voltages at the Flyback Generator Supply (0.48V) and Frame Power Supply (0.32V).
I tested RL2 which tested to be around 650KΩ, which according to the markings should only be 1Ω. I replaced it with a 1Ω 1/8W metal film resistor and put it back together. Notably, the Bomarc schematic I found online for the Classic I lists RL2 as 2.2Ω, but the markings on this one were clearly 1Ω.
Now when I test it, I get "full" vertical deflection but the picture is unstable, jittering/scrolling vertically.
Turning the vertical size adjustment, I can only get a stable image by vertically squishing it down to half of it's size.
Any idea what's wrong now? I've replaced so many parts in this I'm not sure where to look next.