G5 won't boot. White LED lights when power button is pushed, click heard.

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Level 1

8 points

G5 won't boot. White LED lights when power button is pushed, click heard.

Unlike some other non-booting G5 stories, mine never makes it past this stage. It's a dual 1.8ghz G5 powermac.

The white LED above the power button turns on when the power button is pressed, a click is heard, but it does not go any further. The LED does not flash at all... no grey screen, no hard-drive access, nada.

When I push the power button with the aluminum side removed (but with the transparent insert in place), I can see the fans twitch like they are going to start spinning, but then immediately stop.

I've tried resetting the PMU, replacing the PRAM(CMOS) battery, another identical type of video card, blowing out the dust with compressed air, removing and swapping memory, but always get this same result.

There was some renovation done in the house recently, but the machine was gently wrapped and moved away from the work. However after 2 weeks of sitting there, it now won't start.

Any help is appreciated. If the 'clicking' of the power supply is being heard (also clicks when I plug in the power cord), does that mean the power supply is likely working? In which case, is it likely a logic board issue?

One thing I noticed upon closer inspection, after removing the main fan, is that the higher processor seems darker than the lower one. Is there a way to remove one processor to test for hardware failure?

Dual Powermac 1.8Ghz, Mac OS X (10.5.5)

Posted on Sep 22, 2008 9:29 PM

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Answer 1

Sep 23, 2008 10:36 AM in response to subculture

This is EXACTLY the same as I am getting with a dual 2GHZ G5. It too was working fine was left unpowered for a while and now does this clicky thing.

I've tried re-seating things, including RAM, replaced the battery, but no difference.

Lets hope there's a simple answer.

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Answer 2

Dogcow-Moof

Level 8

36,833 points

Sep 23, 2008 3:25 PM in response to G3PBtoG52GHZ

I can't say for sure, but when I had the "click" problem and took my machine in (AppleCare) it was the power supply. 😟

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Answer 3

subculture Author

Level 1

8 points

Sep 23, 2008 9:23 PM in response to Dogcow-Moof

Anyone know what it costs to replace a power supply on a dual G5 1.8? Either via Apple, or other method?

Will Apple store charge me to diagnose the problem?

Anyone know if one of my cpu's is possibly toast? Are symptoms different?

Thanks for the help so far, and in advance.

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Answer 4

Sep 23, 2008 10:01 PM in response to subculture

Hi subculture,
A power supply is not to difficult to replace. The lower processor must be removed. It is much easier to lay the Mac on its side. A used power supply can be found on ebay. There are 2 main power connector that connect to the logic board. Those can be tested with a DC voltage meter against a pinout chart for your particular model and can be found on google.

Powermac G5 2004 Model
Power Supply P1 Connector
Pin# Signal Color ------ Pin# Signal Color
1 +5Vstb Purple --------- 13 GND Black
2 GND Black ------------- 14 Power ON Green
3 FANtach White/Yellow -- 15 GND Black
4 GND Black ------------- 16 Reserved
5 Reserved -------------- 17 GND Black
6 GND Black ------------- 18 RTNaud(GND) Black
7 +12Vaud (12V2) Yellow - 19 GND Black
8 GND Black ------------- 20 +5V sense Red
9 +3.3V sense Orange ---- 21 GND Black
10 GND Black ------------ 22 -12V Blue
11 GND Black ------------ 23 GND Black
12 Reserved ------------- 24 Reserved

Power Supply P2 Connector
Pin# Signal Color ------- Pin# Signal Color
1 +3.3V Orange ----------- 9 +5V Red
2 +3.3V Orange ---------- 10 +5V Red
3 +3.3V Orange ---------- 11 +5V Red
4 +3.3V Orange ---------- 12 +12V3 Yellow
5 Reserve --------------- 13 +12V3 Yellow
6 +12Vfan Yellow -------- 14 +12V1 Yellow
7 +12Vfan(12V2) Yellow -- 15 +12V1 Yellow
8 +25V White ------------ 16 RTNfan(GND) Black

Power Supply P3 Connector
Pin# Signal Color ------- Pin# Signal Color
1 +5V Red ---------------- 5 +5V Red
2 GND Black -------------- 6 GND Black
3 GND Black -------------- 7 GND Black
4 12V2 Yellow ------------ 8 +12V2 Yellow

Regards

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Answer 5

subculture Author

Level 1

8 points

Sep 30, 2008 10:25 PM in response to David Roland

Thanks David, that's very helpful.

First though, I need to know that it really is the power supply that is the problem. How can I rule out the processors, logic board, or other possible problems?

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Answer 6

subculture Author

Level 1

8 points

Oct 8, 2008 12:21 PM in response to subculture

I took it to the Genius bar at Eaton Centre, happy to let them evaluate it at no charge. Unfortunately their diagnosis is that it's likely the Logic board. They were able to make the fans spin, so think the power supply is okay. Likely that the logic board, and perhaps 1 or both of the CPUs are bad. In either case, it's more than the G5 is worth... logic board is $1200 by itself.

Guess I'll see if anyone is interested in the parts or the case!

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Answer 7

Oct 8, 2008 6:21 PM in response to subculture

Hi subculture,
The genius bar was unable to give a definitive answer. Several components aren't likely to go out, simultaneously. Did they reseat your graphics card? The is the first step is to remove and re-install the graphics card. It could have moved from its original seated position when you moved your computer.
Also, there is a small cable that runs from the power button to the logic board. Press each those 2-connections firmly while booting to see if there's a difference.

Regards

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Answer 8

Oct 9, 2008 5:51 AM in response to David Roland

David, I'll try that on mine too.

Thanks.

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Answer 9

Oct 9, 2008 3:37 PM in response to David Roland

David,

You are a genius! I pulled loads of things out and put them back in. It fired up!

Excellent, thank you.

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Answer 10

subculture Author

Level 1

8 points

Oct 20, 2008 10:15 PM in response to David Roland

David Roland - when I read your post, I thought... well I've already tried reseating everything and nada.... but your suggestion about the power cable that runs to the logic board made me think "hmmmnnn...".

I simply pressed down on each end firmly, closed up the G5, prayed silently to several holy bodies from the major religions, and pressed the power button.

And it %^&^ &(&#$%#%@ WORKED!

It's been up for a few minutes now, I've reinstalled all the memory I'd pulled out, doing a sw update.... will repost here if my machine dies again in the near future... but at the moment all looks great!

You rock! May the karmic energies bless your future and shower you with happiness! Thanks dude!

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Answer 11

Das Geek

Level 1

34 points

Nov 1, 2008 7:33 PM in response to subculture

I am having the exact same problem. I have followed Apple's Service Source trouble shooting steps. I had decided that the logic board must be bad and ordered a used one from eBay. It has the same problem. I cannot confirm the eBay board is good but I think it probably is fine.

I am now wondering if it is a bad processor or power supply. I have tested the power supply with a voltmeter. I get a 5 volt reading between pin 1 and 23. According to Apple's Service manual that is the only test advised for the power supply. I have not been able to swap processors with different ones to check for a bad processor. I have removed the lower processor per Apple's service manual.

I remember ready somewhere that you cannot swap processor locations.

How can I test for a bad upper processor?

Is there more I can test on the power supply than the 5v across pin 1 and 23 that Apple recommends?

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Answer 12

Das Geek

Level 1

34 points

Nov 6, 2008 7:27 AM in response to Das Geek

There is a very busy thread about failing PowerMac G5s on this board:

http://forums.macworld.com/thread/103827?tstart=0

I think there is a problem with this model. There are a lot of these going out at the 3 to 4 year mark. This is not normal for Apple and "Pro" equipment from them.

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