Beige G3 boot from **** problem; open firmware issues; bad motherboard?

Question

Dear all,
I'm having huge boot/startup problems with my beige G3 that had been happily running OSX 10.3.9, but for purposes of this discussion we can (mostly) revert to OS 9. Originally, the machine was a G3 @300; was upgraded more than a year ago to a ZIF G4 @500.
To make a long story short, it won't boot from any hard drives, will not boot from any OS X CD, and will only occasionally boot from a 9.x startup CD (whether Apple or Norton Utilities). I think it's an open firmware issue, possibly caused by a bad motherboard (rev. 2).
All this started happening after I used techtool pro, but I think that's coincidence (even though I acknowledge that, for cops and computer users, there are no coincidences.) Also, as discussed below, I'm having the same problems with an HD that wasn't even in the computer when all these things began.
Here are some of the things I've done.
--repeatedly reset PRAM, both with key combinations and removing battery. The only time it will boot from a 9.x CD is after resetting PRAM.
--removed all add-on PCI cards.
--removed additional VRAM
--removed all memory cards and tried replacing one at a time.
--disconnected both existing hard drives and replaced with an older OS 9.x hard drive (approx 60 mb) that I'd used before. Also tried different ribbon cables.
--unplugged floppy drive
--disconnected PCI ATA disk controller that I'd been using for running a large (1.8 gb) hard drive.
--regarding open firmware: readenv usually shows totally normal default AND installed settings. Using reset-all works fine -- at least it makes the machine reboot, but doesn't solve the problem. reset-nvram does NOT work -- says it's an "unknown word."
--using startup keys like holding down the option key, or shift key, or X key or cmd-option plus two others I can't remember, has no effect. Again, after I've tried any kind of reboot, the ONLY way to get the C-key at startup to boot the CD is by resetting the pram (key combination). Otherwise, the usual result of these experiments is a dark screen on startup -- nothing at all (and the LCD monitor tells me "no input.")
--regarding OSX: sometimes (and I emphasize sometimes) I can get the machine to start booting from an OSX 10.2 CD, but it won't complete the process. Sometimes I get a "prohibited" (as in no-parking, no-smoking) icon; sometimes it will start booting (grey screen, OS X Apple icon), then crash (horizontal grey and white jagged bars); sometimes it will show the OS 9 start icon (the tiny smiling Mac SE), but not boot at all.
--when I get the mac successfully booted with an OS 9.x CD (again, this works sometimes, but not always), the old hard drive with two partitions does show on the desktop and can be accessed. Using either disk repair or Norton Utilities shows the 9.2 system partition on the hard drive to be fine. But if I go to the startup disk control panel, confidently set the 9.2 partition as my startup disk, then reboot, there's no change. It won't boot and I'm back at square one.
--even when I do get successfully booted with 9.x, the machine will still occasionally crash for no reason -- ie when I'm moving a Window.
--the only thing I haven't done is slowed down the processor. It's a ZIF G4 bought more than a year ago from XLR8 your Mac. I'm running at the default 500 mhz, and it's never given me any trouble.
So I think it's a bad motherboard or ROM. Thoughts?
Thanks.

Answer 1

The beige Mac is now operating happily again. My original tentative diagnosis remains the same (although still tentative): corrupted PRAM from bad battery, compounded by bad cables that wrote corrupted data to hard drives, and also (possibly) allowing Tech Tool Pro (a utility that I now regard with deep suspicion) to create a "virtual" startup partition.
A few things I've learned along the way that hopefully may be useful:
--remember that the Ex Post Facto utility can be used to help OS X startup, not just installation. This applies to hard drives, emergency CDs, installation CDs, etc. If you can boot into any working hard drive partition (OS 9 or a backup OS 10), then run Ex Post Facto (same program runs on either OS 9 or X -- don't ask me how) and tell it what system you want to start up from. Also, the utility has sometimes told me that the startup extensions on the disc that I wanted to boot up from were bad, and offered to fix them (which works).
--at least on my Mac (beige, v. 2 motherboard), resetting the CUDA button, resetting the PRAM, resetting Open Firmware and "draining" the memory by unplugging the computer and disconnecting the battery for several hours ALL DO DIFFERENT THINGS.
Specifically, if I'm having trouble booting (from a hard drive or a CD), the FIRST thing I do is restart and resetting the PRAM on the fly -- holding down command, option, P and R at startup, and waiting for the chimes (preferably at least 3-4 times).
If I do that and DON'T hear the chimes, that's my cue for my SECOND action -- restarting into open firmware (command, option O and F keys on startup). That should bring up the black text on white background open firmware screen. View other posts or apple support for details, but if you do PRINTENV and see a bunch of weird gibberish after the default/installed lists, you know that it was messed up and you need to clear it through reset nvram and reset all commands. Be aware some of these commands do or do not work depending upon what version of Open Firmware you have.
After I've rebooted with Open Firmware, then on restart I should be able to reset the PRAM on the fly. If that works, then either let the machine run and see what happens, or hold down the C command and see if it will boot from the CD
Usually, if I've fixed everything as above, the machine will boot into whatever version of OS 9 it finds on a hard drive. That's fine with me -- at that point, use Ex Post Facto to reboot into your OS X. (Before I forget: I used the shareware startup CD creator program BootCD to make an emergency boot CD based on OS 10.2.8 (which theoretically will support a beige mac in native fashion) and Disk Warrior, the god of disk repair utilities. Even though the CD should boot just by holding down the C key on startup, it doesn't -- but if I use Ex Post Facto to boot it, no problems (although the process is very slow -- be patient). Then I can fix almost anything using Disk Warrior.)
If none of the above works, then I'll try resetting the CUDA (on my beige minitower, it's a very small black button inconveniently located between a PCI slot and the side of the computer housing). Hold it down for 15 seconds. That should REALLY clear the PRAM. I know this does something different from the previous steps because this is the only action (except the battery disconnect -- next) that clears the date and time from the memory.
If all else fails, I will unplug the computer and disconnect the battery, then push the CUDA button for 15 seconds and let the machine sit overnight.
One final finding -- I thought I'd fixed everything, but both my hard drives suddenly quit working, I discovered that during all this repeated connect/disconnect of things, one of the male pins inside one of the connectors on my Acard ATA PCI card had broken off. Not good. Fortunately, the card had a second connector, which works fine. And I did some extensive shaking of the computer to make sure (I hope) that the broken pin hadn't landed on a circuit board.
All this took more than two weeks, and the advice of this board was much appreciated. Now I'm on to my next adventure -- trying to figure out why a combo Firewire/USB PCI card won't mount an external drive on Firewire, but will on USB. I've tried two cards with same result -- but a Firewire-only card works just fine.)
Regards to all,
Graham