Boot problem with iMac G5

[Wordman]

I have had an iMac G5 in my kitchen for years. Recently, and suddenly, it froze up. It no longer fully reboots. After several dozen attempts, it seems to randomly display one of the following, with about equal regularity:

• monitor never turns on
• Grey "Apple logo and spinner" screen comes up, but with funky things happening to the video syncing and interlacing (every other line offset by 20 pixels or so, etc.)
• Grey "Apple logo and spinner" screen comes up, but when moving onto the "solid blue" phase of booting, screen shuts off (but machine still runs).
• Boot reaches the "solid blue" stage fine, but then never proceeds. Can see moving cursor, but doesn't do anything. Sometimes shows spinning beachball.

Here's what I have tried doing:

• Booted from installation CD. Shows same behavior.
• Booted into Hardware Test. Runs fine. Every test passes.
• Booted into single user mode. Ran fsdk, which finds no problems.
• Zapped PRAM. No improvement.
• Booted into open firmware mode and ran reset-nvram and reset-all. No improvement.
• Unplugged overnight, and did most of the above again.

From all this, I'm guessing that the problem is that the video card is hosed. So, questions for you all:

1. Is there anything else I can check?
2. What is your diagnosis?
3. How easy is it to change the video card in an iMac G5?
4. How much would doing so cost?

[DeltaMac]

Sounds like a typical problem with an iMac G5, especially the early ones (1.6 or 1.8 GHz), where there can be some failed capacitors on the logic board. I have seen the same symptoms that you describe multiple times. Replacing the logic board is the fix. The video chip is part of the logic board, and cannot be separately replaced.
You might check locally for a repair shop that can tackle replacing the logic board. You may even want to try it yourself, if you can locate a replacement logic board that doesn't cost more than the value of your iMac G5.

[nixgeek]

Apple used to have a repair extension program for the iMac G5, but it's been closed as of December 15, 2008. You can try and take it to Apple anyway and see if they might still cover it. I know someone who had similar problems with an iMac G4 and although the repair program for that Mac had expired, they still replaced the parts at no charge. It's worth a try.

[jtwitt]

I just reloaded OS X install disks and it seems to have fixed my problem...

[DeltaMac]

Good!
What problem was that? Was it anything related to the OPs problem, which is a known issue in the iMac G5 hardware?

[jtwitt]

The operation of my G5 deteriorated over the past week. After spending about two days researching on-line for solutions, I was told by a techy friend to reload the Tiger OS X 10.3 software. This solved my problem with hanging up on boot at the blue screen. I'm still reloading other software (iLife) and need to test it, but everything else seems to work ok.

[DeltaMac]

Although yours seemed similar. the OP had hardware issues, which is very common on the iMac G5, and is not helped by a simple software reinstall. Glad yours was a simpler process, and you are working again....

[stilbite]

You may want to take the back off and look at the capacitors on the motherboard. If you see any of the tops bulging (they should be perfectly flat) or any brown crud coming out of any of them... your motherboard is on its way out. known fault with original G5's, 17in and 20in.