Issues PowerMac G4 (AGP). Result of dead PRAM battery?

Discussion in 'PowerPC Macs' started by PowerMac G4 MDD, Dec 6, 2014.

  1. PowerMac G4 MDD macrumors 68000

    PowerMac G4 MDD

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    #1
    Hey everyone,

    I have had this PowerMac G4 (AGP) since around 2010, and I am not sure why I had not addressed this issue on MacRumors sooner.

    Anyway, one thing to note is that the PRAM/clock battery seems to be dead. When I turn on the machine or restart it, I will not get any signal on the screen. Once I push the PMU reset button a few times and turn it on, it displays picture and boots fine. I have to press this button in order for it to boot, EVEN if just a restart. It sleeps and will awake from sleep just fine, but start-up is an issue.

    Can the dead PRAM battery really be causing this chaos? Perhaps there is something else going wrong?

    (Note: Even if running correctly, after a PMU reset, I see a red LED light illuminated, next to the RAM. I cannot remember whether this is normal or an error light).

    -Thanks
     
  2. bunnspecial macrumors 603

    bunnspecial

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    Kentucky
    #2
    Have you tried a PRAM reset(hold :apple:+opt+P+R on startup and wait to hear the second startup chime)? I know that I had some weird issues with my Sawtooth when I first got it that this cured.

    BTW, the red light on the logic board is normal when the computer is powered on.
     
  3. PowerMac G4 MDD thread starter macrumors 68000

    PowerMac G4 MDD

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    #3
    Hmm, I actually cannot remember whether I have ever tried that on THIS Mac. I'll go ahead and try it, and I'll report back.
     
  4. kettle macrumors 65816

    kettle

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    #4
    I 'acquired' a PowerPC xserve that was going in the skip - all that was wrong was the PRAM battery.
     
  5. PowerMac G4 MDD thread starter macrumors 68000

    PowerMac G4 MDD

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    #5
    Yeah, I am guessing that could be it, then. Doing a PRAM reset didn't work.

    ----------

    I tried it but it didn't work... I have a feeling its the PRAM battery. I made the thread, though, in case that was not actually the issue. I wonder why a dead PRAM battery would affect this machine so.
     
  6. bunnspecial macrumors 603

    bunnspecial

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    #6
    FWIW, my Sawtooth does not currently have a battery installed.

    I've noticed that some PPC machines can act "screwy" with a low/bad battery installed but are okay with the battery disconnected. Pismos are especially notorious for this(and the PMU battery for those is expensive), but I've noticed it in other models. I leave my Sawtooth(along with several other computers) plugged into a UPS, but probably only start it once a week if that often. It always starts immediately every time, and leaving it plugged in(with the UPS) ensures that the time is always correct when I do turn it on.
     
  7. PowerMac G4 MDD thread starter macrumors 68000

    PowerMac G4 MDD

    Joined:
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    #7
    Hmm... I have the feeling I have tried that before, but I'll go ahead and see what it does w/o a battery.
     
  8. weckart macrumors 601

    Joined:
    Nov 7, 2004
    #8
    Yes. I picked up all my Pismos cheaply because of depleted/dead PRAM batteries. Pismos will not start with those connected but can boot fine without them.

    I managed to find a replacement on eBid.net for $9 from a US seller that had 25 but those have gone now. Others are charging crazy money for those.
     
  9. bunnspecial macrumors 603

    bunnspecial

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    #9
    OWC wants $35 for the battery now. I paid $40(before shipping) for my Pismo! The PMU battery had been disconnected long before I acquired the computer.

    Of course, that's small change compared to what even an aftermarket main battery costs-the last time I checked on one they were running over $80! The one I have now will at least give me 10-15 minutes powered up(or a few hours asleep)so I can move the computer around without shutting it off. I'd like to find a couple more "dead" batteries and try rebuilding one.
     
  10. weckart macrumors 601

    Joined:
    Nov 7, 2004
    #10
    $35+ seems to be the going rate. Considering I paid between £9 and £15 for my Pismos that was never going to happen. I should have stocked up on the cheapies I found on eBid but to be honest, PRAM batteries are not a must-have on the Pismo, especially when your main battery is neither use nor ornament.

    You have piqued my interest on rebuilding the batteries. What does that entail?
     
  11. InuNacho macrumors 65816

    InuNacho

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    #11
    I don't have the battery in my Sawtooth either. Computer thinks its 1969 but hey whatever.
     
  12. bunnspecial macrumors 603

    bunnspecial

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    #12
    Basically you crack the battery casing open and replace the cells inside of it with new similarly dimensioned cells.

    Apparently the cells in Pismo/Lombard batteries are "standard" sized and thus can be sourced from battery sellers. I found a few how-to guides on the internet specific to the batteries to these computers, including the exact specs for the replacement cells. Replacement cells are not cheap($40-50 from what I recall) but at least you know exactly what you are getting, unlike the unknown aftermarket batteries.

    A few years back, I was making a killing on Ebay buying up dead rechargeable battery packs for the motor drives on Canon F-1 Cameras and rebuilding them. These haven't been made since the 80s and were Ni-Cd, so are beyond useless. People still using F-1s(myself included, when I take a notion to shoot film) like the rechargeable pack since it can run the motor drive at 5fps vs. 4.5fps for the similar alkaline battery pack.

    In any case, the F-1 battery packs contain 12 AA sized Ni-Cd batteries. I bought bought AA NiMH batteries with solder tabs on Ebay for a relatively low price in bulk, and could rebuild a battery pack for a couple bucks in material and an hour or so of work.

    A spot welder can make the job even easier, as you can spot weld "straps" directly onto the batteries rather than messing around with soldering them together. At least here in the US, most locations of the Batteries Plus chain have this equipment on-site and will rebuild battery packs(although I'm not sure they do computer batteries). They are not cheap, though-a number of years back, they quoted me $60 to rebuild the F-1 battery pack, when I could do it myself for about $8.
     
  13. weckart macrumors 601

    Joined:
    Nov 7, 2004
    #13
    Thanks for that. I researched online and unfortunately it just does not sound cost effective unless you want to make it into a side industry or have no other choice, such as with your Canon.
     

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