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Thread: G4 Sawtooth goes from live to stone dead and back

  1. #1
    Join Date
    Jan 2006
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    2

    Default G4 Sawtooth goes from live to stone dead and back

    My old G4 has gotten very unstable. Here are as many particulars as I can recall --
    PowerMac G4 500 Mhz
    RAM = 256 Mb (was 4x256 but I pulled 3 sticks ... details below)
    boot drive is a Seagate Cheetah 34 GB (second drive is 25 GB ATA)
    OS X = 10.4.3

    I did not buy this machine new -- it came configured as is from an imploding dot bomb back in about 2000. I have not done any hardware upgrades or repairs. (I'm not unwilling or unable -- it's just a kickin' machine, even at its advanced age!) It is the primary fambly machine (the dot bomb was smart enough to attach it to a 23" cinema display ) used for all the important stuff -- photos, music, work from home, etc.

    It has had persistent (but sporadic) issues waking from sleep -- going back at least to the Panther upgrade about 2 yrs ago. Lots of SBBOD problems, particularly when waking at the LOGIN screen. Many hard shutdowns ensued. But it was still alive, and generally quite stable once underway.

    About a month ago, immediately after moving it, it would not start. Not a spark, whir, grunt or whisper when I pushed the power button. Did some research . . . prayed it wasn't a power supply. Bought a fresh battery and reset the PMU button. No joy. Pulled one of the RAM sticks and reseated the other 3. It fired up! Ran well for a couple of weeks, (I shut it down at night instead of letting it sleep) and then we had a power outage the other day (no UPS). When the power came back, G4 went back to STONE DEAD.

    I pulled all but one of the RAM sticks ... no joy. Removed and reseated the battery + reset the PMU. No joy.

    Tonight I tried switching the RAM to a different slot (no effect) then removed the battery again, reset the PMU button . . . and it fired up! This post is being written from the machine in question.

    I am truly befuddled at this point. This has the air of one of those electrical gremlins that will drive you out of your mind. I have found a few posts around the web that describe suspiciously similar problems (which is how I came to replace the battery and fiddle with the PMU) but the fix always seems to come down to voodoo, holding your mouth just right, and various incantations rather than an actual diagnosis and repair. Although this isn't a production machine, it is "mission critical" to the household.

    This site seems to be a refuge of people who are sane, knowledgeable, and the equivalent of the bearded Unix guy that used to tell Dilbert "here's a nickel, go get yourself a nice little PC..." (Plus I bought some iBook memory here and the folks that run the place seem to be way on top of things. )

    All guidance greatly appreciated.

  2. #2
    Join Date
    Aug 2001
    Location
    Grangeville, ID USA
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    9,142

    Default

    I wonder if you just happen to have sub par power supplied to it and it is scrambling the PMU and motherboard ROMs. Seems like it is based on the PMU and not RAM or anything else.

    Other than that.......................
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  3. #3
    Join Date
    Feb 2001
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    on the landline, Mr. Smith
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    7,787

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    Worth trying an OF reset Rick? Couldn't hurt at this point.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  4. #4
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    May 2001
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    1hr N/W of LA LA Land
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    Quote Originally Posted by ricks
    I wonder if you just happen to have sub par power supplied to it and it is scrambling the PMU and motherboard ROMs. Seems like it is based on the PMU and not RAM or anything else.

    Other than that.......................
    I have a Furman rackmount power conditioner with a LED voltage meter on the front. It's not plugged into my UPS, but it's on the same circuit. That meter fluctuates all the time here. The tube amps it supplies don't care much about that stuff though.

    All my sensitive computer/recording gear is on the UPS. The Macs run 24/7, and are solid as a rock. I think as these Macs get older they become more sensitive to bad power, and being cycled through sleep/shutdowns. They seem to be happier if you leave 'em on with the drives spinning. The only time i shut 'em down is for maintenence, cleaning, or the occasional electrical storm.

  5. #5
    Join Date
    Jan 2006
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    2

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    Thanks for the insights. I'll try the following steps -

    * Get a UPS and minimize the sleep/shutdown cycles. The power angle is interesting, because the circuit that the machine is on now (since we moved) just seems unstable to me. We get some inexplicable circuit breaker action every now and then.
    * Restore the RAM back to 4x256 mb
    * Not sure about the OF reset... risks involved ?

    anything else??

    thanks mucho
    Dave

  6. #6
    Join Date
    Feb 2001
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    on the landline, Mr. Smith
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    No risk on the OF reset. A little lower level than a PRAM reset; incorporates the PRAM reset plus a bit more.

    I would agree that the UPS is a safe bet, and would be first on the list if you suspect less than good power. Sags or brown outs (low voltage) can do real damage, and a surge protecter only helps with a high voltage issue.

    After that we can move on and do an OF reset.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

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