DMB@PSUVMA.BITNET (11/18/86)
I had a problem similar to yours (a black vertical line in the center of the mac, and then eventually a totally black screen except for a thin vertical line which what was remaining of the screen) It turned out that one of the wires on the power supply/video board had desoldered itself because of the heat. The folks at the repair shop just resoldered it and everything was fine.