Blue Screen freeze on iBook G4?

Question

I am posting kind of as a last resort considering the fact that it's going into a holiday weekend, so if I have to take it in it'll have to wait until next week.
Anyway I have a iBook G4 1.2 GHz, with 512MB RAM (256 internal, 256 user slot) with now a 100 GB hard drive. About a week ago I was using the computer in the afternoon around 3pm (everything seemed to operate normally), and when my wife went to use it that night around 9:30pm and it had frozen up. The mouse and keyboard wouldn't respond, so I reset using the power button. After the reboot it seemed OK for about 1-2 minutes then I got a kernel panic. So I rebooted again thinking that maybe a software update might be in order since it was Leopard at the time. The software update downloaded the software then froze upon installing the updates. At this point I was unable to get the computer to respond. I tried a Tiger disk, and the computer would not start from the disk. I also tried the usual things such as resetting PRAM, safe mode (didn't work) resetting the PMU, open firmware, verbose mode (freezes here too), single user mode (which didn't indicate any problems) I then hooked it up in Target Disk Mode on an iMac 800 f/p and was able to get access to the drive, so I zeroed out the drive attempting to clean out any residuals that may have been there. I reinstalled the OS via Disk Utility Restore, and Carbon Copy Cloner as I have an image of the computer on the iMac. All of which resulted in the same result booting to the blue screen and freezing. I then used the System Restore disk to see if that would work with no luck. However the Apple Hardware test did work, which ran successfully after 2 run throughs, but I could get nothing else to work. Reading through these forums and other places it seemed that it might be a RAM or Hard Drive issue. I removed the user RAM chip with no luck. So I thought a hard drive replacement might help so I spent several hours this past Sunday replacing the hard drive. Upon returning home I attempted to reinstall Tiger which it booted up the disk nicely and started the install. It got to installing the printer drivers and froze up during the HP drivers. Upon rebooting I was unable to get it to read the disk. After having the flu the past couple of days I attempted to tackle it again today, I was able to install Tiger via Target disk mode onto the computer from the iMac, and upon completion it booted up on the iMac screen beautifully and seemed to be working correctly. I then rebooted both computers, and the iBook froze on the blue screen again. I tried all the tricks again, and it didn't respond. I then reset the PMU and it booted up to the desktop with a message saying that the clock was reset. I shut down so that I could test the stability of the problem, and started it up again about 5 minutes later, and it logged right in and got the the desktop. Upon running Software Update the computer froze again, and I am unable to get it back to the desktop.
So my question is, any other ideas? Could it be the internal RAM chip? Could it be the logic board? Apple Hardware tests are still showing that everything is passing.
Just a quick recap of the steps that I have taken.
Reset PRAM
Reset PMU
Attempted safe mode
Single-user mode reported no errors
Attempted verbose mode
Tried TechTools Pro
Tried DiskWarrior
Zeroed out drive
Reinstalled OS
Attempted Software Restore from CD
Ran Apple Hardware Test (passing everything)
Replace 60GB hard drive with new 100GB drive
Reinstalled OS
Reset PRAM/Single-user/Verbose/Safe/PMU again still getting frozen blue screen
Any help or insight would be greatly appreciated.
Thanks,
Todd Ernst
Message was edited by: Todd Ernst

Answer 1

Hey Todd,
Sorry to hear your problems continue. All companies stop at board level replacement, we go a lot deeper here .
I was looking over your posts tonight, both here and at the bottom of that other thread. I'm beginning to think that you have a bad Mobility Radeon 9200. There is a known failure rate on this chip. I actually have a 1.2 GB 12" logic board with a bad reballed 9200. I shouldn't have reballed it because I could never get any video out of it especially with the shim repair. Luckily like I reported on that other thread this chip is used in a lot of GPUs. It's a ATI Mobility Radeon 9200 4x AGP. I think I have a list if you're interested.
I lucked out since I was trading with someone who had bought a 1.2 thinking it would work in his 1.33. It didn't so he traded it to me for a digital camera I had repaired. I dropped it in the 1.2 12" and ta dah! My wife uses that one now.
This might sound a little stupid, but when I put the logic board back in I didn't apply any thermal paste because there was no residue from a previous application .. pads stuck to the heatsink which I assumed were acting in place of the thermal paste.
One thing I did notice on these G4s is that those 2 mounting studs have failed on one iBook I worked on. That would result in a bad contact with the heat sink. Superior corrected this when he reballed it.
Also you're right those pads on the chips are thermal transfer pads. I think they're silicone based. The problem with paste is that it tends to thin out with heat and loose contact with the heat spreader. Here's what the manual says about those pads:
"Replacement Note: Any time the heatsink is removed or a replacement heatsink is
to be installed, make sure new thermal pads are applied in the following orientation:
• Small rectangular pad at the upper end of the thermal plate
• Largest pad in the middle of the thermal plate
• Square, medium-sized pad at the lower end of the thermal plate"
eMail me if you want to read this for yourself.
Richard