Power Mac : Black screen, LED light & loud fans

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Power Mac : Black screen, LED light & loud fans

Alright, here are the symptoms and what I have attempted to do.

Start Power Mac G5, LED lights up on the front of machine, black screen, no chime, ... then 2 minutes later the fans start spinning (sounds like a airplane).

What I have tried :
- does not boot in Safe Mode
- PRAM reset does not work
- disconnected optical & hard drive, still does not work
- tried target mode, still does not work
- cleaned the entire computer, still does not work

It was working perfectly fine until I moved the computer.
Help!

Power Mac G5 (Late 2005), Mac OS X (10.4.11)

Posted on Feb 15, 2011 7:41 AM

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Answer 1

BDAqua

Level 10

239,177 points

Feb 15, 2011 11:17 AM in response to Genxmaclean

Might be time to replace the PRAM Battery, 4 years is close to their lifespan, far less if ever without AC power...

See which one your G5 has...

http://eshop.macsales.com/item/Newer%20Technology/CR2032/

http://eshop.macsales.com/item/Newer%20Technology/BAA36VPRAM/

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Answer 2

Genxmaclean Author

Level 1

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Feb 16, 2011 7:48 AM in response to BDAqua

Excellent.
I will try and let you know.

Thanks 🙂

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Answer 3

Genxmaclean Author

Level 1

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Feb 16, 2011 12:23 PM in response to BDAqua

Changed the battery and still has the same symptoms.
What do I do now 😟

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Answer 4

BDAqua

Level 10

239,177 points

Feb 16, 2011 3:04 PM in response to Genxmaclean

Not sure which G5 PSU pinout this is, but...

http://www.insanelymac.com/forum/lofiversion/index.php/t105113.html

http://www.applefritter.com/node/6561

http://jimwarholic.com/2010/03/measuring-imac-g5-power-supply-voltages-at-connec tor-plug-pinouts.php

G5 PSU pinouts...

http://www.applefritter.com/node/6561

Service Manual with take apart instructions...

http://www.eserviceinfo.com/download.php?fileid=25193

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Answer 5

japamac

Level 7

24,400 points

Feb 16, 2011 3:26 PM in response to Genxmaclean

It was working perfectly fine until I moved the computer.

Sounds like something got jarred loose.
Reseat memory, graphics card and processors.

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Answer 6

Genxmaclean Author

Level 1

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Feb 16, 2011 4:33 PM in response to japamac

how do you reseat the processor?

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Answer 7

Feb 16, 2011 7:49 PM in response to Genxmaclean

So i have had EXACTLY the same problem after moving the computer from one home to another. Black screen, fast spinning fan, but the LED lights up on the front of the screen.

I took it to the Apple Store for repair and after keeping it 2 days the response was:

- Logic board is the problem
- Can't replace it, apple doesn't make the parts anymore, throw machine away

So, can someone advise me? Is this advice to be trusted and do indeed have a new 80 pound paper weight?

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Answer 8

Apr 12, 2011 7:10 PM in response to robosalsa

I have 5 single and dual processor g5's All of them blew one thing or another over the last 6 months (3 power supplies and 2 mother boards). There has to be something within the system that blows due to overworking with the newer systems. Mac knows you have to upgrade. Funny haha. I have macs as far back as my Mac Plus from the 80's, ci's, 8500's, FX, g3's... All still running but not in daily production, But All my newer g5's DEAD.

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Answer 9

Apr 14, 2011 8:11 AM in response to Genxmaclean

You say LED lights, is it constant, or does it flash in a sequence? have you reset the SMU?

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Answer 10

Mar 20, 2013 4:30 AM in response to Doug Mokaren

As a follow-up, nothing worked. Had to toss the computer....

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