Ack! Where's my PMU switch?

Discussion in 'Mac Help/Tips' started by vniow, Apr 10, 2003.

  1. vniow macrumors G4

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    #1
    I just recieved a 500Mhz Powermac today with the intention of repairing it (missing parts) and I tried to remedy some problems by resetting the PMU switch on the logic board, but it seems like there's not one!

    What do I do now?

    I'd post a pic but I don't have a digital camera, but I've looked at the diagram and where there's supposed to be a switch, there isn't one.

    It's an AGP (not Gigabit Ethernet) model.

    Thanx.
     
  2. Sun Baked macrumors G5

    Sun Baked

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    #2
    Is this how the board is layed out?

    Only G4 One older I had was the PCI...
     
  3. vniow thread starter macrumors G4

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    #3
    That's the one, where there is supposed to be a switch, there are four solder points.

    Blech.
     
  4. vniow thread starter macrumors G4

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    #4
    Also...

    The reason why I was going to reset the PMU in the first place was because after I installed RAM, a hard drive, the motherboard battery and a video card (the parts that were missing) it didn't detect my USB keyboard/mouse, no video whatsoever came out, the power on light was green (or is that normal?) but nothing beeped so I decided to reset the PMU switch to see if that fixed anything, but it doesn't seem to be there.
     
  5. Kid Red macrumors 65816

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    #5
    My G4 wouldn't boot after a power outage today [even tho on 20 min UPS] and paid $40 to an Apple reseller to reset it. It's right next to the battery on the new QS's not sure about the old ones. My older now sold G4 450 blew it's power supply and I had to have it replaced. I wonder if the reset button is new?
     
  6. LimeiBook86 macrumors 604

    LimeiBook86

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    #6
    Give your local Apple Store a ring, they should be able to help, or call the tech support line.

    Hmmm, could something be covering it? Do you have an AirPort card or any other things that might bloick your view of it? is it under something? Lift up parts of the board near the processor maybe...
     
  7. vniow thread starter macrumors G4

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    #7
    Okay, I've practically taken the whole thing apart looking for anything that may contribute to this....and nothing.

    The thing that boggles my mind as that according to the scematics (I downloaded a service manual) there's supposed to be some sort of switch near the battery at a port called S1 and on mine there's nothing but solder points.

    On top of all that, it won't boot into anything, no video whatsoever and since I can't seem to reset the PMU to see if its the logic board or not, I'm right back at square one.

    There's no Airport card installed and the only thing installed in any slots is the video card and none of these are anywhere near where this switch is supposed to be, does anyone else have an AGP (non Gigabit Ethernet) to confirm this?
    Or what a green power light vs an orange one means?

    Anybody know of an electrical diagram so that I can solder one on or something?
     
  8. MacBandit macrumors 604

    MacBandit

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    #8
    Reset the PRAM. Hold down the Apple-option-p-r keys right after hitting the power button. The computer should chime (this is good) continue holding those keys until it has chimed at least 3 more times. Release the keys and your computer should start.

    Oh, and a green light means power on. An orange light indicates sleep mode.
     
  9. MacBandit macrumors 604

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    #9
    Another possibility is that of a bad RAM module. If resetting the PRAM doesn't get it booting try removing all the RAM cards and installing one at a time in the first slot and seeing if the computer starts if it does then try adding one again and again until it fails to start.
     
  10. vniow thread starter macrumors G4

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    #10

    Ha, thanx, but one of the problems is that USB doesn't work either so I can't hook up a keyboard to it to reset the PRAM (which I would do next)

    All the RAM is fine, I've mixed and matched all three sticks in different slots so either something else is wrong or all three sticks (unlikely) are bad.

    Glad to see that the light are normal (my now sold Digital Audio's were orange all the time)
     
  11. Computer_Phreak macrumors 6502

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    #11
    maybe try touching the solder points with something conductive, perhaps the PMU switch is supposed to be there but wasn't put on, or was removed or something.
     
  12. MacBandit macrumors 604

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    #12

    EEEEKKK!!!! NOOOOO!!!!:eek: :eek:
     
  13. MacBandit macrumors 604

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    #13
    Have you looked at the backside/underneath of the mother board? Have you tried turning it on with all drives disconnected from the mother board?
     
  14. Computer_Phreak macrumors 6502

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    #14
    would you care to explain?:confused:
     
  15. vniow thread starter macrumors G4

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    #15
    There's nothing on the underside that even remotely resembles a switch and I've tried turning it on with everything except basic power cables and the video card disconnected.

    Methinks the logic board may be bad.[​IMG]
     
  16. LimeiBook86 macrumors 604

    LimeiBook86

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    #16
    Maybe the motherboard was doctered/hacked/or moded and the switch was taken off, where did you get the board agian?
     
  17. vniow thread starter macrumors G4

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    #17
    The board came with the computer which was a 500Mhz G4 Server (could that have anything to do with it?) with some missing parts that I could find easy replacements for so I thought it would be like the Digital Audio (I miss it now...[​IMG]) which was basically the same thing, some missing parts, easy to replace, fix up, but it seems like this one isn't as simple....


    Anybody know where I can get an AGP logic board for cheap?
    Those are pretty scarce, the ones you see on eBay (or anywhere else for that matter) are of the Gigabit Ethernet which uses a different power supply so I'd have to replace that too if that was all I could find.

    <sigh>
     
  18. VegetaPunk macrumors 6502

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    #18
    The diagram posted above states that its a button not a switch are you looking for a switch only or have your tried looking for a button as well. Sorry if this sounds stupid, just tring to help also when I get home I will look at my mobo I have a sawtooth 500mhz agp......
     
  19. vniow thread starter macrumors G4

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    #19
    Ok, yeah its a button according to the manual, I got mixed up, but my main gripe is that there's nothing there at all, no button, no switch, just four solder points.

    And thank you so much for looking at your MB (when you get home) to confirm/deny this, this computer is really frustrating me and I think that I screwed up when I decided to buy it.

    <sigh>
     
  20. VegetaPunk macrumors 6502

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    #20
    no prob(for checking mobo) it wont be for 4 more hours ( 3 am in arizona) Im a student and so Im forced to work graveyard shifts at the company I work for. :(
     
  21. MacBandit macrumors 604

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    #21
    Why would you blindly want to try to short solder connections together on a motherboard without knowing EXACTLY what you are doing?
     
  22. MacBandit macrumors 604

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    #22
    What do you mean the USB doesn't work? How do you know? I would plug the keyboard in and try zapping the PRAM even though you don't think it will work.

    I have looked at the G4 server manual and it doesn't mention a PMU switch so I am thinking they don't have one.

    Have you made sure the power supply is set to 110?

    Last but not least I found an article of value that might help.

    http://docs.info.apple.com/article.html?artnum=95066


    Also here's one on testing the power supply.

    http://docs.info.apple.com/article.html?artnum=58561
     
  23. Computer_Phreak macrumors 6502

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    #23
    well, if you are going to replace the motherboard anyway, I wouldnn't see any harm in doing this as a last resort.
     
  24. MacBandit macrumors 604

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    #24
    Well what if you replace the motherboard and the same thing happens? Then you realize it wasn't the motherboard and you just fried a perfectly good motherboard.

    From what I have read the G4 servers do not have the PMU button.
     
  25. vniow thread starter macrumors G4

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    #25

    I did plug in a USB keyboard and mouse, neither lit up so its safe to assume that the USB conmtroller isn't working for some reason.


    I'm starting to think that too, it looks like there was an option to have one there, but there's this little strip of wire that permantly connects two of the solder points.

    Yes.


    Thank you, but that's for a PCI model which has a slightly different architecture than the AGP.

    Thank you, I will try that soon.
     

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