Apple Power Macintosh 7100/80AV - Manual (Page 41)

Troubleshooting Symptom Charts/Video - 7
Video
Screen is dark, audio
and at least one drive
operate, fan is
running, and LED is
lit
1 Adjust brightness on monitor.
2 Replace video cable.
3 Try using known-good RAM SIMMs.
4 If monitor is attached to DB-15 connector, attach monitor to
HDI-45 connector. If problem goes away, verify VRAM
SIMMs on video card are good. If SIMMs are bad, replace
them. If SIMMs are good, replace video card.
5 Replace monitor. Refer to appropriate monitor manual to
troubleshoot defective monitor.
6 Replace logic board. Retain customer’s SIMMs.