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Troubleshooting Symptom Charts/Video - 25
Video
Screen is black, but
boot tone is present,
drive operates, fan is
running, and LED is
lit
1 Adjust brightness on monitor.
2 Clear parameter RAM. Hold down Command-Option-P-R
during startup but before "Welcome to Macintosh" appears.
3 Reset Cuda chip. (Refer to “The Cuda Chip” in Basics chapter
for instructions.)
4 Reset logic board. (Refer to “Resetting the Logic Board” in
Basics chapter for instructions.)
5 Replace monitor cable.
6 Remove all SDRAM DIMMs and try replacing them one at a
time to test. Replace any bad DIMMs.
7 Test with known-good monitor. Replace monitor if necessary.
Refer to appropriate monitor manual to troubleshoot
defective monitor.
8 Replace logic board.
9 Replace processor module.