On Sep 19, 2010, at 8:44 AM, muttdog wrote: > On Sep 18, 11:35 pm, Kris Tilford <[email protected]> wrote: > >> In my experience the causes of freezes that are most common are: >> >> 1) bad RAM or mis-seated RAM > > Pulled the RAM and gotten the same results > >> 2) bad HD (especially if the fan has died) > > Replaced with known good HD and gotten same results > >> 3) hardware issue or short (logicboard, optical, ports, etc) > > I have shimmed the logic board - doesn't seem to have > any effect at all. > >> 4) software (easy to test, boot known good system or CD) > > Tried reformatting and reinstalling 10.4. Install would freeze > about halfway through. Was successful installing by firewire > from another iBook in target mode. But when I booted up, it > froze right after the desktop loaded. > > I'm ruling out software - happens whether OS is installed or not. > I've seen RAM problems before - usually prevents the machine > from booting up properly. This machine develops the problem > after it's operational for several minutes... possibly heat-related? > That would lead me back to logic board whether it's the vchip > or some other fault.
I think you're on the right track. I've seen iBook G4 models exhibit the kind of behavior you are experiencing. As you have done, I isolated it down to heat and probably video circuitry issues. A bad video chip or circuit will hang or freeze an iBook. The fact you could install via firewire when it wouldn't via the internal drive is also something I've seen with iBooks (G3 and G4). It works because the video circuitry isn't tasked significantly during installation. Both G3 and G4 iBooks have the video chips attached to the logic board via the BGA (ball grid array) technique. I've seen a few G4 iBooks and PowerBooks where the chip developed one or more broken solder joints, but it's more likely that the problem with a G4 iBook is the thermal pad(s). G4s have a pretty substantial heat sink clamped over the cpu, bridge chip and the gpu. If the thermal pads have been changed from the original, a pad that's too thick will not do the job and will cause overheating and thus freezing of the computer. Thermal grease doesn't work in this application. Only a set of thermal pads that are the right thickness will work -- Apple originals, in other words. In your case, it may be that reused thermal pads are too thin. Or new ones too thick. Or it may be that one or more internal traces have been damaged (cracked) by overheating in the past and that's why they act like a shutdown switch when the computer heats up. My guess is that you need to replace the logic board. That was the only fix for the G4s I worked on that showed similar symptoms. I will tell you that this is one frustrating problem to diagnose. The iBooks I've worked on even would pass the Apple Hardware Tests, and then go on to play DVDs for hours. Then, whammo!, the next time the started up and got warm, they shut down/froze. NTSC (never twice the same caca). HTH, Jim Scott -- You received this message because you are a member of G-Books, a group for those using G3 iBooks and PowerBooks (we run a separate list for G4 'Books). The list FAQ is at http://lowendmac.com/lists/g-books.html and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To leave this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g-books Support for older Macs: http://lowendmac.com/services/
