Powermac G4 Random Shut-Down/Beeps on Startup

[bunnspecial]

I've just recently(as in over the last two days) started having a problem with my Powermac G4 Digital Audio. I have made no hardware changes to the computer in this time frame.

Basically, the computer will randomly power off when I'm using it. Sometimes it will happen during startup, sometimes within a few minutes of startup, and at other times I can get several hours of use out of the computer.

Sometimes, when it powers down, I can restart it immediately. At other times, it will be a little while before I can restart it. I'm guessing this may be a sign of a PSU on its way out-any thoughts on how likely this is?

In addition, now whenever I startup the computer I get a single beep accompanied by the power LED flashing. As per Apple, it looks like this is indicating a POST problem.

http://support.apple.com/kb/ht1547

However none of these seem applicable. Once the LED stops flashing, I will then hear the start-up chime and the computer will boot as normal. I have not counted the number of flashes(I didn't realize that was significant until finding that page just a few moments ago) but will do so on my next start-up. In the mean time, does anyone have any suggestion as to what could be causing the problem?

I have reset the PMU, and in addition have installed a new clock battery.

 

[DeltaMac]

Does your Mac recognize ALL the RAM memory that you have installed?

Be sure to try reseating all memory sticks.
If each stick is 256MB or 512MB, you could try booting with only one stick at a time, to check for worse problems with a single stick. Certain memory failures might disable part of a stick, but let it boot with the other RAM detected. If only the faulty stick is in place, it might not boot at all. Maybe...

Do you have any additional PCI cards installed (USB, second video card, etc.) Be sure to try removing those extra cards (if any), and check if that clears the beep at the beginning of boot.

Do you have the Apple Hardware test CD for your digital audio G4?
It's not a huge test of everything in the system, but worth trying…

From what I see in troubleshooting, if those few items seem OK in your opinion, then I would begin to suspect the processor, or the power supply.

Finally, does the initial beep come from the internal speaker - or from somewhere else, like the hard drive? some failing hard drives can make really unusual sounds, depending on the manuf. (beeps, varying tones, sirens, along with more common clicks, etc.

 

[bunnspecial]

Does your Mac recognize ALL the RAM memory that you have installed?

Be sure to try reseating all memory sticks.
If each stick is 256MB or 512MB, you could try booting with only one stick at a time, to check for worse problems with a single stick. Certain memory failures might disable part of a stick, but let it boot with the other RAM detected. If only the faulty stick is in place, it might not boot at all. Maybe...

but woDo you have any additional PCI cards installed (USB, second video card, etc.) Be sure to try removing those extra cards (if any), and check if that clears the beep at the beginning of boot.

Do you have the Apple Hardware test CD for your digital audio G4?
It's not a huge test of everything in the system, rth trying…

From what I see in troubleshooting, if those few items seem OK in your opinion, then I would begin to suspect the processor, or the power supply.

Finally, does the initial beep come from the internal speaker - or from somewhere else, like the hard drive? some failing hard drives can make really unusual sounds, depending on the manuf. (beeps, varying tones, sirens, along with more common clicks, etc.

To answer your questions that I can-

Yes, it does recognize ALL the ram.

I actually had quite a few PCI cards installed-a Motorola WiFi card, an Adaptec SCSI card, and an Adapted USB 2.0/Firewire card. I removed the SCSI and USB cards, but seem to be still having the problem.

I don't have the hardware test CD.

The beep is definitely coming from the system speaker.

Also, one other comment-I found one the bosses that support the modem rolling around between the modem and logic board. How it got loose, I don't know, but I just went ahead and removed the modem completely as there's zero chance that I'll use it(I don't even have a landline).

Also, one last thing-even when the computer refuses to power on, I can press the power button on the front of my Studio display(which is powered through the computers power supply via the ADC connector) and the button will illuminate briefly, telling me that the display is getting power. I pulled the power connector from the logic board, and I was able to measure +5V from ground to pin 15(the "power on" pin) as well as +28V from pin 22(the ADC connector). So, it seems as though, at least as that goes, everything is as it should be.

 

[bunnspecial]

Well, I think that I solved the problem by switching out the logic board, power supply, and the case while I was at it for good measure.

In all seriousness, I found a Quicksilver semi-locally for a decent price(actually a little less than I paid for the DA). I pulled the HDDs from the DA, along with all of my other upgrades(ram, graphics card, PCI wireless, USB, and SCSI). I put the HDD, graphics card, and ram that came in the Quicksilver in my DA, and for the time being have set it aside. I'll play with it more as I have time.

I have a big scanning project I'm working on now that needs to be done pretty quickly, and I NEED a working G4 machine(or at least its easiest on a G4). Some of the scans I've been doing take 10+ minutes, and it's unbelievably frustrating to to have the machine shut off in the middle of doing so.

Plus, if my Dual 1ghz processor card ever gets here, I have a feeling the install will be a LOT easier in the Quicksilver(since that's what it's meant for) than in the DA.