Chosen Solution
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-chimeDiagnostic LED 3 flashes very shortly (10ms)Diagnostic LED 2 flashes very shortly after LED 3the right fan runs normalthe Power-LED (which is see through the case) is onthe optical drive goes in begin statethe 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?
- the main powersupply:
- 12V is OK and stable
- 3,3V is OK and stable
- 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!!! Best regards Georg
Your diagnostic lights indicate that the power supply should be replaced. My service book doesn’t get into the specific voltage leads. Here’s the part: iMac G5/Intel Power Supply When replacing note that at first it appears that there is no connector for the power lead running under the logic board but just continue to pull it out till you see the connector.
