MBP Logic Board Replacement - No Power

Discussion in 'MacBook Pro' started by cutty2k, Feb 28, 2012.

  1. cutty2k macrumors newbie

    Feb 28, 2012
    I recently had a repair come in, a client spilled coffee on a 2008 Macbook Pro A1281. It was DOA, so we ordered a new logic board from our buddies at Blue Raven. Installed the new board (APN 661-4835) and that has failed to solve the issue.

    The MBP does not start at all, no chime, no hd noise, nothing. The magsafe shows a green light, and the battery is fully charged.

    Things I have tried:
    PRAM Reset
    SMC Reset
    Swapped Memory
    Replaced DC-In
    Different Magsafe
    cursory examination of the logic board for any physical defects

    At this point, I'm 99% sure it's a hardware related issue, since the whole things was pretty doused in coffee when it came in. I was thinking it could be the battery cable, but I don't know that that would affect startup attempts that bypass the battery, using just the magsafe. If it's not a power issue, then I was thinking ram, but neither set of sticks I've tried has worked. The A1281 had several iterations, each with its own logic board. There is a slight possibility that the original board I pulled was the 661-4834, which is identical to the 4835 with the exception of more VRAM and a 2.53 ghz chip rather than the 2.4. I don't think that should make a difference, and I'm pretty sure that the original WAS the 4835, so I'm disinclined to think that's the problem. I'd like to think that the new board wasn't DOA from blue raven, and I'm confident enough in my skills to be fairly certain I didn't damage the new board during installation, so barring any possible logic board faults, does anyone have any idea what could be causing a no-boot situation such as this? Any help would be appreciated!
  2. jkouyoumjian macrumors newbie

    Mar 1, 2012
    Boston, Massachusetts
    There could be more wrong...

    There could be more wrong than the board. I repair liquid spilled boards for a living and I've seen this a million times. In order for these boards to start up, everything must be just right. If your replacement logic board is indeed good, then something else connected to it is causing it not to start.

    The most likely causes are:

    1) The computer is told to start up when a standby voltage generated by the power manager is grounded. The keyboard could be shorted internally from the liquid and the power button is being held down (electrically) or is in some other way shorted and causing it not start.

    2) The LVDS cable/display module could be shorted and causing it to not start.

    3) The Airport/Bluetooth connector/cable is shorted.

    4) Some combination of factors.

    You can try this to diagnose:

    1) Disconnect the LVDS cable and try starting with the keyboard power button. Leave the LVDS cable disconnected.

    2) Disconnect the Airport/Bluetooth/Camera cable and try starting with the keyboard power button. Leave the Airport cable disconnected.

    3) Disconnect the rest of the peripherals: hard drive, optical drive and track pad.

    4) Disconnect the keyboard and try starting by momentarily shorting pin 5 on the keyboard connector to ground. The unit should turn on.

    If you have a meter, check pin 5 of the keyboard connector. You should read ~3.38 volts from the power manager with the MagSafe plugged in and the light green. If this reads zero, the keyboard is likely bad (the power button is shorted).

    You can also test the Blue Raven board on the bench, not installed in the unit. Simply connect a known-good MagSafe connector and a fan. You should see a green light on the MagSafe adapter. This means the power manager is running (and has turned the light green). If you short pin 5 of the keyboard connector to ground, the unit should start (fan should turn on). If it does not, the logic board is 100% bad. Don't run it for more than a few seconds without the heat sink installed. Just long enough to see it turn on.

    I can give you further troubleshooting steps - feel free to contact me at my email: joe@microreplay.com.

    By the way, I am one of the original founders of Pre-Owned Electronics, which six years ago became Blue Raven. I am no longer affiliated with them in anyway (I sold out six years ago before the current management team came in).

    Let me know if I can help.

    Joseph Kouyoumjian

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