Apple Macintosh Performa 577 - Manual (Page 22)

Troubleshooting Symptom Charts/Video
(Continued)
- 5
Video
(Continued)
Screen jitters or
flashes
1 Verify that adjacent computer equipment is properly
grounded. Move electrical devices away from monitor.
Temporarily shut off all fluorescent lights in area.
2 Check that all ground cables are secure.
3 Replace analog board.
Out of focus 1 Perform focus adjustment. Refer to “Focus” in Adjustments
chapter.
2 Replace analog board.
3 Replace CRT only if one part of display remains out of focus
despite adjustment of focus controls to their limits.