My power mac 2.3 recently start acting up.

Here is what is does:
1. The screen will go black.
2. The fans will steadily speed up to full speed in about 1 minute.
3. If I reboot it will work for a random amount of time.

I though it might be a heat issue so I cranked up the AC in the room and it didn't fix it.

The system worked fine since I bought it used earlier this year.

Any ideas?

Do you hear boot-chime?
If yes, try to go to OpenFirmware console (during booting, hold down Command + Option + O + F until you've arrived at the Open Firmware prompt.). If you can go to OF, please post it - then we can check further.

If you dont here chime, you may have a serious HW-problem. That means that the low routines for checking basic HW-components fail. This can be mainly caused by CPU, PSU, RAM, Graphic-card or one oft the main components on motherboard. You can try to remove battery and press reset-button underneath RAM-sockets. Sometimes this may help....
In some cases PSU is the problem - maybe capacitors are going to be defect.

Sometimes it also helps to swap the CPU modules.

It does chime once I turn it back on. I can't get into the firmware since my video card is a 1950. It will boot to Ambient just fine. But after 5 minutes or so, the screen goes black and the fans spin up.

I will try swapping the cpu's and see what happens. Thanks!

If you swap cpus, you need thermal calibration - otherwise your G5 wil sound like a starting jetfighter, till MOS takes it over and does the thermal control......

Quote:

That did it thanks Koszer! Now back to ami-back and file system testing.

@Harry You are right it is loud but I can't get into OF so hopefully I don't have to reboot often.

Don't have a MAC-Graphicscard?

> Don't have a MAC-Graphicscard?

See comment #4.

My PowerMAC G5 2,3GHz has a similar problem at moment. After getting warm, he won't boot anymore - no chime to hear. Turning off for some minutes and he will start normal. When once started, there are no further issues - it works till it will turned off or a reboot is needed. AppleDiagnocticCD does'nt find any problem.

I found out, that this has something to do with CPU-module. Changeing them solves the problem. So I dismounted both cpu-modules completely and found a damaged capacitor (beginns to run-out). I have now to purchase one and to change - then we will see whether this solves the problem.

On the picture you can see this capacitor (only one module is affected)

41547611ay.jpg


[ Editiert durch Amigaharry2 03.07.2021 - 21:17 ]

Quote:

Good luck with this one. I heard that CPU module is a hard nut to solder. One of my friends (a skilled one with electronics) did a G5 CPU module recap for me and said that it's a multi-layer board filled with a lot of copper. It dissipates the heat like crazy. Be sure to pre-heat the PCB well.

Capacitor is changed - PowerMac works again! These capacitors are "easy" to change, because they are soldered on surface (not to a layer).

But for sure, I'll look for a G5/2.3GHz-Cpu-module - don't now when next capacitors will die......
.

A small update:
PowerMac works, but there is a small thing, I don't understand.
When quitting MOS with A+A+ctrl, PowerMac restarts back to firmware. When quitting from Ambient-menue, it hangs most time (nit allways), before entering OF-console (do hear chime)! Must turn off and on again - then ist works normal.
Quitting MacOS doesn't make any problems......