Power Mac G5 will not power on with air deflector in place.

Discussion in 'PowerPC Macs' started by kaanook, Oct 16, 2011.

  1. kaanook macrumors newbie

    Joined:
    Oct 16, 2011
    #1
    I purchased a Mac G5 AS-IS for parts/repair. I thought it would be a good project for me to learn to fix Macs. (I’m a PC tech.)
    Well this is where I am with this project. When I purchased the mac, the computer powered on but no video. Upon tearing down the unit, I found that it had sprung a leak. To make a long story short I ended up replacing the CPU/LCS unit. Prior to install this I inspected the Power supply for any damage inside the unit and appears the water damage was only limited to the exterior of the casing. Internal circuitry was unscathed. I inspected the logic board for any water damage and did not appear to have any water damage. Once CPU/ LCS were installed, I was having problems powering on the unit. After doing a little research. Tested the logic board battery and found that it was dead. Purchased/installed the battery. Voila. Unit now powered on. I thought I was out of the water. ……Not so fast!...... I put the air deflector and side door in place. Now, Computer will not boot. Power LED, Chime, fans spin, and no video. After playing around with it while, I have found that the computer boots to OS no problem when the air deflector and side door is removed but will not boot with air deflector and side door in place. Once unit is powered on and I can now put in place the air deflector and door with no problems. Computer comes in and out of sleep mode no problems. This is where I’m stuck. Here is what I have done in attempt to resolve this problem to no avail.

    Reset the PRAM and NVRAM
    Reset the PMU (reset button on board)
    Reset PMU Unplug power cord for 2 minutes
    Ran Thermal calibration
    Ran Apple Service diagnostics v2.5.8 all pass
    Replaced video card
    Replaced Ram
    Reseated CPU
    Replace PRAM battery
    Replaced the hard drive

    I haven’t found any one else with this similar type of issue and this is where I’m at.

    This is a Power PC G5 June 2004 2.5 DP LCS
     
  2. 666sheep macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #2
    Inspect air deflector sensor and its cabling. Sadly it requires disassembling entire unit. See in service manual where it's located. Maybe leaked coolant caused corrosion of sensor or its cable and when it's sending signal to logic board short-out occurs.
     

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