User Guide

Troubleshooting Symptom Charts/ Video Problems - 19
Solid gray screen,
however, normal
startup boot chime,
power LED on, and the
fan is running.
1 Reset parameter RAM. Hold down <Command> <Option> <P>
<R> during startup.
2 Check that video/USB cable connections are secure between
monitor, adapter, and computer.
3 Boot off the system CD that came with the unit. Do you see a
normal screen display now?
Yes : Reinstall system software. (You must use the system
software CD that came with the unit to get the correct version of
Mac OS with the appropriate iMac enablers.)
No : Go to next step.
4 Reseat the internal RGB cable that attaches to the A/V
interconnect board at J5.
5 Reset the CUDA chip and try again. If the problem persists,
reset the logic board. (See “The CUDA Chip” and “Restarting
the Logic Board” earlier in this chapter for instructions.)
6 Verify that the following cables are attached securely:
• Internal video cable that attaches to the logic board at J16
and the A/V interconnect board at J2.
• Internal RGB cable that attaches at the A/V interconnect
board at J5 and the video board at P301.
7 Replace the analog/video board. Exchange like-for-like,
there are two versions of the board.
8 Replace the internal video cable that attaches to the logic
board at J16 and the A/V interconnect board at J2.
9 Replace the A/V interconnect board.
10 Replace the logic board.
11 Replace the internal RGB cable that connects at the A/V
interconnect board at J5 and the video board at P301.
12 Replace the CRT. Replace like-for-like, there are two
versions of the CRT.