Steve Darden
Level 2 (160 points)
iPhone

Q: Mac Pro power supply replacement?

We're on our yacht in Hobart, Tasmania. No access to Apple Store.

 

Re: Mac Pro 2006, how do I assess whether the power supply is failing?

 

I ask because we have experienced several times over the past couple of years the following issue. Typically in the morning I see the Mac Pro has shut down and will not startup. I go through the SMC reset procedure as per Article: HT1806. The straight forward "press the SMC Reset button" never works. Sometimes just pulling the power cord for a few minutes works. Yesterday was one of the "hard cases". None of the usual voodoo worked, so I left the Mac Pro for about 6 hours with power and all cables disconnected.

 

When I reconnected power the MP began a familiar 17 second cycle, both sets of Memory Riser Card Diagnostic LEDs illuminate for about 3 seconds, fans start, shutdown (repeat).

 

Pressing down the SMC RST button stops this loop, but still cannot startup.

 

Yesterday I pulled the top memory riser, left MP off for 30 minutes then when I reconnected power I could startup successfully. Shutdown, reinsert top rise, restart success.

 

I called Apple support, authorized a case. The tech went off to consult for 10 minutes or so, then came back and said "we think your power supply is probably stuffed".

 

To obtain a replacement supply here in Hobart is going to be difficult and expensive. So any advice on how to improve our assessment of the true source of this problem would be much appreciated.

 

The famous and helpful "Hatter" once suggested to another troubled Mac Pro owner to "leave the computer disconnected from power overnight". My experience is that the longer time disconnected is related to success, but I do not understand why. Why is overnight helpful?

 

PS - I've not done the following procedure yet, and because it is from the 2008 Mac Pro service manual it may not apply to the 2006 exactly as written. I'm including this info for the benefit of searchers who come along in the future:

 

Power Supply Verification

 

To power on, the computer’s logic board requires “trickle” power. If the system fails to power on, first reset the SMC as described in this chapter. If the computer still doesn’t power on, follow the procedure outlined below to determine whether the issue is related to the power supply.

Verify trickle power

Diagnostic LED 2 indicates the presence of trickle power required by the logic board to begin the startup process.

LED 2 should be yellow when the DIAG_ LED button is pressed, indicating that trickle voltage is present.

Verify Power Supply Is Providing Power

Diagnostic LED 8 indicates that the main power is OK and within regulation. Plug in AC power cord, and press the power-on button on the front panel.

LED 8 should be green when the DIAG_ LED button is pressed, indicating that the main power is OK and within regulation.

If diagnostic LED 5 and LED 6 are both solidly illuminated at power up, improperly seated power supply cables could be one cause of this behavior. Check all power supply cable connections to ensure they are properly seated.

 

PSS - I have recently replaced the PRAM battery.

Mac Pro, Mac OS X (10.6.7), 23" Apple Cinema HD, ATI Radeon 3870

Posted on Jun 13, 2011 1:48 AM

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Steve Darden

Q: Mac Pro power supply replacement?

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  • Helpful answers

  • by Eric Ross,

    Eric Ross Eric Ross Jun 13, 2011 1:47 AM in response to Steve Darden
    Level 6 (11,686 points)
    Jun 13, 2011 1:47 AM in response to Steve Darden

    Try running Apple Hardware test on your system. 

  • by Steve Darden,

    Steve Darden Steve Darden Jun 13, 2011 2:33 AM in response to Eric Ross
    Level 2 (160 points)
    iPhone
    Jun 13, 2011 2:33 AM in response to Eric Ross

    Thanks Eric. AHT has never helped me before, but maybe this is the time it will help. Certainly the price is right (if I can get the Mac Pro to reboot - restarting is a challenge as we depend upon Internet Sharing to connect our other Macs to a long range wifi service via external high gain antenna and bridge).

  • by annafromlas vegas,

    annafromlas vegas annafromlas vegas Jun 13, 2011 1:02 PM in response to Steve Darden
    Level 1 (0 points)
    Jun 13, 2011 1:02 PM in response to Steve Darden

    T'he answer to this dors Not necessarily have to focus on t'he problemes  but in t'he soŀution.    You Can go to crucial.com and scan and buy t'he memory cards it needs. At least 4GB to Run Osx. T'hen buy a 24pin cable to t'he Video Card into Your screen.  That should solve hardware problemes however fan and light May still bother you, all comes with Age but you Can always add Moré ram or another Logic board to solve apparent detalls.

  • by Grant Bennet-Alder,Helpful

    Grant Bennet-Alder Grant Bennet-Alder Jun 13, 2011 1:58 PM in response to Steve Darden
    Level 9 (61,418 points)
    Desktops
    Jun 13, 2011 1:58 PM in response to Steve Darden

    Are you getting a chime?

     

    The chime says the computer passed the first part of the Power-On Self-Test, and if enough working RAM and a boot drive can be found, booting is likely. Lack of a chime says something else is amiss.

     

    The usual procedure in cases of no chime is to pretend that something is loading down the power supply. So you remove all the drives and the graphics card and everything except a minimum of RAM, and look for the chime. If you get to the chime, then you add back the graphics card so you can see what is happening, and boot to the Installer DVD. then bring back an item at a time and see when it craps out.