iMac G5 doesn't wake form sleep mode!

[Fallinangel]

Hi,

My old iMac G5 still works quite well considering its age, but it has one major flaw: it isn't able to awake when it's in sleep mode.
In fact, there's no reaction at all when I try to get it out!?
It is as if it was turned of, but there still is a slight fan noise. 😕

Even the start/restart button becomes inactive. Pressing and holding it won't shut the iMac down!!! 🙁
The only thing, that works for me is pulling the power plug and putting it back in!
After that rebooting/restarting is no issue.

Here are some technical details for the iMac:

- Processor : 1.8GHz PowerPC G5
- Memory : 2GB DDR SDRAM
- Graphics : GeForce FX 5200 64MB
- Harddisk : Samsung HD403LJ 400GB
- OS : Mac OS X 10.5.4

Thanks for any help!

 

[techound1]

A computer's PMU (Power Management Unit) is relevant to:

• sleep/wake issues
• battery issues (such as not charging at all)
• power-on issues
• port issues (USB/FireWire ports appear dead).

The Power Manager is an integrated circuit (computer chip) that is usually on the logic board. As the name implies, it is responsible for power management of the computer. It controls backlighting, hard disk spin down, sleep and wake, some charging aspects, trackpad control, and some input/output as it relates to the computer sleeping.

Over time, the settings in the Power Manager may become unusable, which can result in operational anomalies with the computer. Examples include not turning on, not waking from sleep, not charging the battery, or not seeing the AC Adapter, among others.

Perform these steps:
1. If the computer is on, turn it off.
2. Reset the power manager by simultaneously pressing and then releasing Shift-Control-Option-Power on the keyboard. Do not press the fn (Function) key while using this combination of keystrokes.
3. Wait 5 seconds.
4. Press the Power button to restart the computer.

 

[Fallinangel]

Thanks but it doesn't work!
It still shuts down when entering the sleep mode.