G5 7.2 DP won't boot

[GondolinOnMyMind]

I just got this one. Excitedly set it up and turned power on. Aaand it won't boot.
Symptoms

• power led is lit when button is pressed, it goes off right after
• fans do rotate slowlishly.
• fans do rotate at full speed when the plastic cover is removed. Also a red led is lit on the logic board. Both go back to normal when cover is put back
• no chime
• no picture

Observations

• There is no pram battery
• 2 Simms on #1-slots
• display adapter (radeon 9600) on the agp-bus
• no other leds are lit on the logic board
• computer is relatively dust free
• power goes off when power button is kept pressed ~10 seconds

What have I done:

• reseated memory and display adapter
• booted several times with various configurations of no memory installed, with memory, no display adapter installed, with display adapter
• also tried with and without a hard disk. I do not have a hdd sled.

As I don't have other simms, display adapter nor battery I can't swap parts. Battery is in mail and should arrive next week.

I should add that the very first boots did not succeed at all; the fans twitched and then kept still. I removed the simms (those were on #4-slots) and moved to #1 slots, reattached the display adapter. At some point those actions (or the matter that the computer got fed enough power as it had been without power for a couple of years) helped and I was faced with the symptoms above.

Any help is appreciated. This is a beautiful computer and I would love to get it running.

 

[eric]

I had some very weird behavior with my G5 as well (not sure the exact model) but a few things that may help:

Press the CUDA button on the motherboard, then try to boot

Put the RAM in different pair slots - oddly mine wont ever take RAM in the first pair, but same ram works always in 2nd.

Try resetting the PRAM while starting - see if it even gets that far.

Try different RAM, mine was very picky.

 

[RetroTheory]

Back in late 2003 I was given the offer to buy a dead G5 Dual 1.8, for very very little money. It was doing what yours is, power on, immediate protection shutdown.

I removed 1 processor in turn and discovered one of them had a short . One cpu had visibly blown mosfet or transistor . I ran that machine for a while in single processor mode, and eventially just removed the offending mosfet and reinstalled the cpu without it.
It worked away fine as a dual g5 for as long as I had it

So it could be a hardware fault, like a shorted capacitor , or discrete components thats triggering protection shutdown .

 

[GondolinOnMyMind]

I have some kind of more information on this. It seems to boot when it is cold, ie been powered off overnight. I even managed to boot from a G4 dvd until it froze. The image on the display was very distorted, and thus I suspect that the graphich adapter might be at fault. I guess the image should be readable at least when booted from older dvd, righ?

New symptom is that after some time powered on, maybe 5 mins, the fans start gradually spin faster and faster until they are full on. Maybe I did not originally keep it powered on long enough to notice this.

Does this computer support boot from USB?
Are there restrictions on what kind of hdd´s can be used?

When I get the new battery I´ll try also to cuda reset. And I guess I need to also test with just one cpu.

 

[GondolinOnMyMind]

Short update. New battery and pmu reset did not help.
On the open firmware console the computer was usable quite long time, something like an hour.
Booted then again with old dvd and got the same very distorted picture. This makes me think it might be the display adapter.

edit: emu -> pmu. Thx autocorrect

 

[GondolinOnMyMind]

Update. Finally got a new display adapter and that has solved the distorted picture issue. I have now run this computer three days, most of it of course hibernated or power save mode, what ever it is called.
I have also disabled one cpu in open firmware, and that may have solved the issue of the computer not being able to boot. During tests I removed one cpu physically, and tried running with only one, swapping the cpu between boots. This did not lead to anything however.

 

[ApfelKlassik.de]

INteresting! How do you disable a CPU in OF?

 

[GondolinOnMyMind]

I followed the instructions on http://mac-classic.com/articles/disabling-cpu-cores-on-a-multiprocessor-system/

1. Boot into Open Firmware (Command + Option + O + F during the boot process).
2. To view the current boot-args settings, enter the following command:cr boot-args type crprintenv boot-args will accomplish the same thing, but will output the hexadecimal value of each character in boot-args rather than readable text.
3. Enter the number of CPU cores to utilise with the following command:
   setenv boot-args cpus=1
4. You will need to reenter the current value of boot-args if you want to preserve it. For example, if the result of Step 2 was:debug=0x4 okThe command would read:
   setenv boot-args debug=0x4 cpus=1
5. After the ok response, continue booting your system with the mac-boot command.