Symptoms of a failed Logic board?

Discussion in 'MacBook Pro' started by bkryzer, Sep 2, 2009.

  1. bkryzer macrumors newbie

    Sep 1, 2009
    Recently my PowerBook G4 12" is having problems booting. When I go to power up I head the Apple Chime and the screen remain black. This problem is not always present, sometimes it will function normally. I reset the PRAM and the PMU, but this doesn't seem to have done anything. I have also noticed that when the machine fails to start that the sound of the CPU powering up is not present. I can tell just by listening to the machine if it is going to boot. If it doesn't boot there is no sound, however, the caps lock and number lock lights are present. Can any of you guys give me some advice? I am suspect to the logic board slowly failing. Are these some of the symptoms associated with a failed logic board? Pleas help!
  2. Hannify macrumors member

    Jun 6, 2007
    It's always a little hard to diagnose without actually seeing your machine, but this sounds like classic logic board failure to me. The give away is the keyboard light activity in conjunction with the cpu failing to rev up. If it was a display problem you would not experience those symptoms. How does your sleep light respond when this is happening? This isn't a 100% test, but often times the sleep indicator will "stick" in the on position when the logic board is going south (edit: at least on intels; not sure about PPC now).

    Someone else will have to give you the low down on how much it will cost to replace; it's been a while since I've been in the PPC loop. The best bet is probably to just take it in to Apple and see what they can do for you.
  3. iBookG4user macrumors 604


    Jun 27, 2006
    Seattle, WA
    Just to avoid confusion here, the CPU does not rev up, the OP is either talking about the fans or the hard drive. The processor itself does not make a sound. Although it does sound similar to a logic board failure. I would suggest taking it to an Apple Store and having them diagnose it, they'll give you an estimate along with the problem and you can then decide what you want to do.
  4. Hannify macrumors member

    Jun 6, 2007
    Absolutely correct. I was merely using "rev up" as a term of convenience. However there is the issue of "cpu whine," which is what I thought the OP was referring to; of course exactly what generates that nebulous sound has never exactly been satisfactorily established. Integrated circuits certainly don't normally produce audible noise if they're in spec.

    In retrospect you're probably right that the OP is hearing (or not hearing) fan/HDD/optical drive noise. Which would indicate something very bad indeed, if the fans don't even spin up, as these are controlled at a very low level. Fried logic boards aren't fun.
  5. docal97 macrumors 6502a


    Jun 28, 2006
    They can run a hardware diagnostic test for free on your machine. They also have an out of warrenty flat rate repair fee of 311 plus tax and that will repair anything in your machine out of spec, ie. Broken. This is for out of warrnty repairs and is sent out to a repair depot.

    I hope this helps.
  6. DePhantom macrumors newbie

    Sep 23, 2009
    I have the EXACTLY the same problem as you. I just purchased a PowerBook G4 15" 1.27(?) Ghz.

    PowerBook G4.
    - The powerbook has problems turning on. when pressing the power button, it does not rev up and make some clicking nose from the bottom right corner. Also the sound of the Fan is not present either.

    - The laptop will freeze either on the apple logo or on the screen most of the time.

    - The laptop will not read both of my rams. somtimes it reads 256MB and sometimes it'll read the 1GB.

    - The laptop has no problem on the screen, the screen seems new, and when the laptop turns on. the screen works fine.

    - Sometimes the laptop will rev up, however no visuals will come up. ie the gray or the apple logo.

    those are the ones i could think at the top of my head.

    macs are extremely expensive, and i saw this powerbook up for sale for $150 so i took the call and bought it. I am a 15 year old student with no real job, and cannot afford to pay anothing over $100 as of now.

    is it really the Logicboard that's the problem?

    if it is the logicboard, how much can i sell this to people?

    Every part except for the logicboard seems in prefect condition. Screen has no scratches, the laptop has very MINOR scratches and scuffs.

    Please reply with more questions so i could give you as specific info as i can.

    thank you in advance :)

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