MP 1,1 will not boot or chime

Discussion in 'Mac Pro' started by LetNightExplode, Oct 12, 2012.

  1. LetNightExplode macrumors newbie

    Oct 12, 2012
    Everything was going smoothly until I tried to add fourth hard drive to the system's fourth bay. I tried to turn on the computer again - white power light came on but it didn't boot from the drive. I took out the 4th drive bay and tried again but it will still not boot. This was possibly the first restart in a while so it could also be an update from a piece of software also. It does not appear to be accessing the hard drives at all. I have removed all external USB sources and I still get nothing. i have tried removing all but the first(system) bay and it stll won't boot.

    No chime, no screen, no dark grey screen. I hear what sounds/feels like the two fans going full power but nothing that sounds like HDD access. I don't know what the normal amount of time would be but it goes for a while - i haven't timed it, I interrupt it because i'm afraid it's damaging my computer further.

    I removed the graphics card - all the drives and but one set of DIMM's with no difference. Fans still stay on full power until I cut power. It does show the white power light on the front though.

    I have reseated all the memory as well - cleaning off as much as I could witha 12oz can of compressed air. Still no difference

    Any help troubleshooting would be much appreciated

  2. LewKellogg macrumors newbie

    Jul 2, 2014
    Me too...

    Same things happened to me 2 days ago. When I check the test leds, the Trickle is on, EFI is on, and GPU is on. No chime, no boot, fans working. No idea either :)
  3. MacVidCards Suspended

    Nov 17, 2008
    Hollywood, CA
    Unplug and hold down power for 20 seconds

    Resets PMC
  4. LewKellogg macrumors newbie

    Jul 2, 2014
    Next Steps

    This particular problem is interesting because it seems to appear regularly on many different boards/forums without a posted repeatable solution. If I missed one or anyone has seen a working solution, please let me know. I have seen posts for Mac Pros (typically 1,1, but others as well) and Macbook Pros.

    Symptoms when booting are:
    • Front panel power light comes on and stays on (no flashing)
    • Disk drives whir a bit as if trying to read
    • GPU fan runs, typically high speed
    • Rear fan runs, not sure about front fan as it is sometimes removed for inspection
    • No Chime
    • Never completes booting
    • Diagnostic LEDs show trickle (yellow), GPU (green), and EFI (green) only when test micro switch is pressed
    • there are no other LEDs lit indicating, for example, a hot or bad CPU
    • Holding the Power button forces a suht down, as it should

    All of the posts I have seen walk through all of the standard troubleshooting steps like resetting the SMC but eventually come down to an unknown issue that might either be a failed logic board or failed power supply.

    I read the service manual and followed the troubleshooting suggestions for the LED results I get, resulting in a focus on the power supply. That seems odd as the fans work, LEDs light, drives seem to work, etc. However, there may be logic in that logic... :) When I unplug PS connection #3 (at B1) the LED diagnostics show only trickle. The other two LEDs do not light. Plugging PS #3 back in, the LEDs come back as before (1,6, and 8 are lit).

    My next step is to measure the power supply voltages to see if the PS might really be the issue, as the service manual suggests. The challenge is testing the supply "loaded" (without unpluggin it from the board or creating a dummy load) because unloaded readings can vary greatly from loaded. Since there is power enough to run fans, light LEDs, etc. I'll have to measure at several, if not all points, to be sure. Anyone have a schematic? :D

    I will post my findings as I progress.


Share This Page