No chime, no startup, no screen but fans and power-LED is on
I have a nice iMac G5 (iSight) on my desk but it doesn't run...
The system does the following:
After pluging in the power-cord diagnostic LED 1 lights on.
After switching it on the following occurs:
- NO (!!!) start-chime
- Diagnostic LED 3 flashes very shortly (10ms)
- Diagnostic LED 2 flashes very shortly after LED 3
- the right fan runs normal
- the Power-LED (which is see through the case) is on
- the optical drive goes in begin state
- the HD sprins up and goes in begin state
The system turns exactly after 1 minute all fans in full blow mode...
What did I have checked?
1. the main powersupply:
- 12V is OK and stable
- 3,3V is OK and stable
2. the other voltages are produced on a combo-board, with the inverter for teh TFT.
I measured the following voltages and they correspond to the printed voltages on the mainboard:
- 3,3V all
- 3,3V run
- 5V all
- 5V run
- 12V all
- 12V run
But there are two lines in the plug on position 1 and 8 (white and gray cables) there is no voltage and they are not GND!
Does anyone can say, what these two cables to have been supposed?
I have numbered the cables of the plug in this way:
| 01 | 02 | 03 | 04 | 05 | 06 | 07 |
| 08 | 09 | 10 | 11 | 12 | 13 | 14 |
When you lay down the open iMac with the top towards you and take a look to the cables then the white and the gray cable should be at the left side...
Btw. I've just changed all the ELCOs on the mainboard with Low-ESR-Elcos, but it is the same problem with the iMac!!!
Is this a good question?