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Power Mac G3 board toast, (possibly) need replacement


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Troubleshooting advice would help too, but I am fairly certain I have a PM G3 beige minitower that is on its way out.  Fresh PRAM battery, all expansions removed, minimal system connected (with the exception of a SATA card later on).  Power supply voltages are golden, within 10% or less of the rating.

 

Symptoms:

  1. No chime at boot but it does boot. OS 7.6.1 and 8.0 can play audio through the speaker when using them in a Norton Utilities envrionment, so I know that part at least works.
  2. Boot RAM test takes a very long time.  After a long period of being unplugged, nuked PRAM or otherwise, sometimes it does not show video at all.
  3. Intermittently responds to ADB power-on/power-off keypresses.
  4. CPU barely heats up, contrary to my experience with the G3 in the past.
  5. Sonnet PCI SATA card, designed specifically for this Mac, being used as a disk, and OS 9.2.2 can see it but OS X of any version cannot.
  6. In fact, OS X can see IDE disks on the motherboard's controller, but no SCSI disks, or intermittently it can see SCSI.  OSX install takes an eternity to complete, which in past runs with this computer, is a new problem--usually it takes about an hour at the most, with this taking up to 3 hours now if it's installed to a CF card under IDE.
  7. OSX 10.1 and 10.2 can complete their installer, but 10.3 kernel panics despite being rated to run on a G3.
  8. All RAM sticks test fine in other machines.

I am more or less convinced this board is gone, but I don't know if there is anything else I can do to salvage it or repair it before I go scouting out a replacement.

 

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The fact that it boots, and is usable (apart from SCSI/IDE oddities) suggests there is some life left.

 

Heat output doesn’t matter (the lowly G3s run cool and the case it decently ventilated), a lack of chime does

suggest something RAM related or potentially backside cache. Strip

it down to one good stick, clean the contacts and keep testing.

 

OS X on a G3 can take an age to install and will be hampered by installing to a CF card, or the optical drive trying to read (burnt?) CDs. 10.3 needs XPostfacto utility to install on a beige G3.

 

Lastly, does a firmware update exist for your SATA card? Some played well with Classic but not OS X, misreporting the drives. The beige G3 is also picky about master/slave setup.

Edited by Byrd
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I agree with Byrd, in that it sounds suspiciously like maybe there's some bad RAM.

 

Can Norton Utilities run a RAM test? (I can't remember). If it does, I suggest you run it (if it doesn't, go look on Macintosh Garden or the like for an application that does and use that). Then if it turns up no errors, do what Byrd suggests and see what happens.

 

Hopefully that helps.

 

c

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Results: I couldn't get the Apple Hardware Test to boot, but I could get it to run TechTool Pro to run on it, which upon attempting a full test of hardware, crashed immediately upon testing the L1 cache.

 

I swapped out the CPU, got the same result, though a markedly faster boot time.
 

I removed the cache module entirely, now doesn't boot at all (powers on, but the power light does not turn on, sits there with seemingly no activity on disk or on screen).
 

Another thing I forgot to mention: when booting after being unplugged when I work on the inside, the computer first goes to OpenFirmware and repeats this message as follows:

 

can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: 

It then reboots, and goes into OS9 just fine.

Edited by sigtau
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Are the ROMs socketed in the Beige G3?

 

This is starting to sound a little strange. You say the hardware test (Apple hardware Test, by the way, won't work on the Beige because it predates AHT by at least two years) crashed while testing the L1 cache, and replacing the module didn't help? Hmm.

 

Do you have another cache module to try? That could be one of the failure points.

 

Also, that strange OF message is concerning. Hence my question about the ROMs being socketed (if they are, maybe there's some intermittent contact somewhere?)

 

c

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ROMs are not socketed, it appears to be some kind of single chip, like a PLCC or something to that effect.  I don't know which it would be, there are no DIP chips on the board.

 

And I think I mis-wrote that post: I tried Apple Hardware Test and it wouldn't boot, but then tried a separate program, TechTool Pro, which tests all hardware facets you can throw at it, and it crashed immediately. OS 9.1, no extensions.

I have a second CPU and I swapped that out, and it crashed with that one too.  Performing a CPU test with both also crashes it.

 

The RAM test, however, succeeded with flying colors.  The RAM is all good.

 

I am all but certain this logic board is toast.

Edited by sigtau
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Hmm, well, if you want, I have an extra (including a CPU and I guess cache card) you can use to confirm the death of your existing board (I think; I'll have to check and make sure it's not packed in storage)?

 

PM if interested!

 

c

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The beige G3 mainboard has a slot for a video RAM expansion. You said there are intermittent issues with the video. You might check if the video RAM is o. K. If you have a working PCI video card in the system and if you encounter problems with the internal video circuittry, you might disable the internal video in the Open Firmware command line (hold ⌘+⌥+O+F upon start, immediately after the boot chime) with:

setenv pci-probe-list fffbffff
reset-all

Then the output goes directly to the PCI video card, saving time, also. The changes take effect upon the restart and can be removed by a standard PRAM reset (hold ⌘+⌥+P+R upon start, immediately after the boot chime).

On the beige G3 mainboard is also a CUDA reset button, as shown in the scheme in this article related to G3 startup problems. Once I found my beige G3 quite unresponsive after an attempt to just install the Dantz retrospect software. A PRAM reset did not take any effect. After some cheerless days with the machine playing possum I found the CUDA reset button to be a very helpful feature to revive the computer. Probably some infomation needed at boot time is messed up and needs to be restored to default parameters in your machine.

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On 5/24/2018 at 4:14 PM, register said:

The beige G3 mainboard has a slot for a video RAM expansion. You said there are intermittent issues with the video. You might check if the video RAM is o. K. If you have a working PCI video card in the system and if you encounter problems with the internal video circuittry, you might disable the internal video in the Open Firmware command line (hold ⌘+⌥+O+F upon start, immediately after the boot chime) with:

setenv pci-probe-list fffbffff
reset-all

Then the output goes directly to the PCI video card, saving time, also. The changes take effect upon the restart and can be removed by a standard PRAM reset (hold ⌘+⌥+P+R upon start, immediately after the boot chime).

On the beige G3 mainboard is also a CUDA reset button, as shown in the scheme in this article related to G3 startup problems. Once I found my beige G3 quite unresponsive after an attempt to just install the Dantz retrospect software. A PRAM reset did not take any effect. After some cheerless days with the machine playing possum I found the CUDA reset button to be a very helpful feature to revive the computer. Probably some infomation needed at boot time is messed up and needs to be restored to default parameters in your machine.

There is no video RAM inserted at all, and I don't have an external video card to test with.  I've done a fresh PRAM and CUDA reset as of this post, and still no change in the board's behavior.

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On 5/21/2018 at 1:24 AM, sigtau said:

i Have 

Another thing I forgot to mention: when booting after being unplugged when I work on the inside, the computer first goes to OpenFirmware and repeats this message as follows:

 


can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: can't OPEN: 

It then reboots, and goes into OS9 just fine.

I have a G3 which is throwing that same error! I had never seen it before and was baffled. I will have to read up on Open Firmware. 

 

I have multiple other projects right now so I set the machine aside for future troubleshooting, but it is nice to have a clue to go on. 

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Keep in mind that the beige G3's went through a lot of revisions and have, in my opinion, more than and average number of quirks.

 

I was not aware that they would boot anything less than Mac OS 8.  7.6.1 is new information to me.  So is the sound simply not working?  And is this the internal speaker or external speakers?  I occasionally have to reseat my Wings cards or things get weird.  Just the way it is and always has been.

 

Boot RAM test is always very long if you have maxed out memory.  Both of mine take quite a while... again, just the way it is.

 

No video on first boot - also not surprising - do you have a PCI video card?  My "main" G3 has a flashed PC Radeon 9200 and will NEVER show video the first time.  I give it about 30 seconds, do command+option+power, then it's good to go.

 

Can't comment too much on CPU heat level - I used to monitor mine and it never got "hot" - maybe 120* F or so.  Usually much cooler than that.  I do have a 486 fan on it, though.

 

Also can't comment on the expansion card issues and OS X - I use onboard IDE for everything... no SCSI or SATA.  OS X was always finicky on these and in this day and age there is not much reason to run OS X on a beige G3 because much more suitable machines are readily available and at not much cost.  Besides, the beige G3 is just about THE perfect OS9 machine.

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  • 2 weeks later...

Beige G3's like good pram batteries and have boot issues without.  

 

Also the VRM is an issue with strange boots also.

 

I had to boot from CD and restart from hard drive every time I unplugged mine and plugged it back in since I dont run with batteries in them anymore.  

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