powerbook G4 fails to boot with error message Machine Check (0) uncorrected -pc... panic (cpu caller 0x 000130504 "Uncorrected Machine check

You might loop Apple Hardware Test (cmd-L or control-L, I can't remember, to toggle from single pass to loop) for five or six loops. Also, when it does boot, what does the Diagnostics area under Hardware in System Profiler say?

You might also try an NVRAM reset, as there may be something odd in the device table that the firmware builds.

stantonfromgoleta wrote:

Further clues: The laptop refused to boot from the installation disk, so apparently the problem is not with a corrupted file in the operating system. My Guru colleague suggests that the problem might be in the boot BIOS. If this is socketed, it might be replaced.

The boot firmware is not socketed. If there were a firmware problem, you would be getting a sequence of tones on boot attempt letting you know there's a problem there.

This may also be due to a tanked backup battery. I could tell stories about that issue, well, I actually have reported some results of replacing that particular item. While I didn't have drastic startup problems, I have seen such occur in the desktop world with exhausted backup batteries. Any Powerbook G4 at this point is very likely to have a useless backup battery in it.

Here's the test: get the machine to boot (you may need to do a PRAM or NVRAM reset again to get that to work) and then close the lid until the white sleep LED comes on. With the AC adapter disconnected, remove the battery for 20 seconds. If during that time the machine turns off, the backup battery is definitely shot.

stantonfromgoleta wrote:

Unfortunately, my Powerbook G4 does not have a backup battery. Does that mean that the most likely fault is the boot BIOS? In which case, the laptop is toast in spite of its working perfectly well when it boots up.

To my knowledge, all PB G4s have a backup battery. It is a 3.6 Volt Li-Ion rechargeable coin cell about the size of a silver dollar that is soldered to a small, oddly-shaped PWB that has circuitry to carefully control the charge/recharge of the battery.

In Titanium Powerbooks, it is located underneath the optical drive, usually, so it takes some disassembly of the unit to get to it.

In Aluminum Powerbooks, it it often found stuck to the top of the optical drive, still requiring some disassembly to get to it.

You can get more details from the iFixit PowerBook repair guides starting here.

As for the boot firmware, if there is a problem, which usually shows up as a checksum error at boot, you would get three or four beeps at startup and it would go no farther. I don't think that your problem is in boot firmware.

Pardon please, but does this little test work for the hi-res models of 15 and 17 inch DDR2 PB G4's? I seem to have a similar problem when in open firmware the date is correct, but the time is off.

romko23 wrote:

Pardon please, but does this little test work for the hi-res models of 15 and 17 inch DDR2 PB G4's? I seem to have a similar problem when in open firmware the date is correct, but the time is off.

In Open Firmware, is the time off by a whole lot, maybe the hours difference between your local time and Zulu time (GMT)? I just booted my TiBook into OF and the time was not exactly correct, as it showed about a 20 minute difference (if I read it right...I was looking for something close when I did it, which is what I got).

The battery out/in test, if it fails, says that the backup battery is weak or gone, in that it is supposed to be able to hold the computer in sleep mode for at least a minute or more while you change batteries. I can think of no other easy test that puts a finer point on it. In my case, with the original battery, as soon as I would take the battery out, the machine just died. With the fresh battery in place, it holds up easily long enough to swap batteries.

Since all of the G4 books use essentially the same battery that Panasonic made and then stopped making in 2005, yes, the test should be valid on any of the models, since they all supposedly support battery swap while sleeping.

stantonfromgoleta wrote:

Apple article TA25911 clearly states there is NO backup battery in

"PowerBook G4 (12-inch) (all models)" and that instead there is a

capacitor to hold the clock for a short period. As long as the main

battery is in place, there is no need for backup.

Could the "no backup battery" apply only to the 12 inch model.?

Now I am wondering if the capacitor is flakey, but that does not

seem to be a likely cause of the no boot if the main battery is

in place. The hardware tests detect no problem, yet it will still

not boot.

I stand corrected. Victim of some incomplete information, it would seem. I just looked over shop manuals for the 12 inchers and there is no mention of a backup battery in the take apart instructions.

While the holdup cap could be a suspect, I would rate that at "extreme corner case" and think the problem would be elsewhere.

Good catch. The HW test probably doesn't depend on the Airport card to actually respond except when tested, which is usually just a test for presence, as I recall. The actual OS, however, might have some more serious interaction with the card, and come to think of it, I have seen a report or two of it causing problems over the past couple of years.

We normally think in terms of removing external peripherals, which doesn't help when an internal peripheral goes south.

Thanks for the update and let us know how the replacement card works out.