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Apple Desktops Discussion of Apple's desktop machines including Mac Pro, iMac, Power Mac, and mini

iMac 20" G5 Power Up Problem


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nowthen2k6

 
Member Since: Jan 24, 2011
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Hello.

First of all, great forum, glad to be here.

Now on to the problem!

I have acquired an imac g5 (a1076) that is puzzling me no end.

At first I thought it was a dead power supply as it was doing nothing when I was trying to switch it on, totally dead.

So I opened it up to check the LED's and LED1 was lit, which tells me its getting some power at least. So I tried pressing the internal power button, nothing, at first, then after a while and a few more presses, it fired up fine, with all 3 LED's lit.

So I turned it off, put it back together and at first few presses of the power button, nothing, then it started up and worked great. I tried a few restart cycles thru' OSX and it started back up no problem every time.

So I powered down and left it for half an hour, tried to restart, nothing again.

Repeated the whole back off process and finally it started again.

I've just tried it again after being switched off and unplugged for a couple of days and at first, no power. I left it 15 mins tried again and after about 3 or 4 presses of the power button(external button, not opened up) it started.

Im leaning towards a power supply on its way out or possibly logic board on its way out.

Am I right in thinking that LED1 & LED2 should be lit with the power cord attached but before power up? Because only LED1 is lit till it powers up then all 3 are lit.

I'd like to try and fix this but don't want to replace the power supply to find out its the board or the other way round!

Any help or ideas would be great

Cheers, Lee.
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pigoo3

 
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Maybe a long shot...try testing/replacing the PRAM battery.

- Nick

- Computer slow, too many "beachballs", read this: Beachballs
- Computer seems slower than it used to? Read this for some speedup tips: Speedup
- Almost full hard drive? Some solutions. Out of Space
- Apple Battery Info. Battery
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nowthen2k6

 
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Quote:
Originally Posted by pigoo3 View Post
Maybe a long shot...try testing/replacing the PRAM battery.

- Nick
Put in a new battery, still the same problem I'm afraid

Thanks for the help anyway
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pigoo3

 
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Quote:
Originally Posted by nowthen2k6 View Post
Put in a new battery, still the same problem I'm afraid

Thanks for the help anyway
Nice try! I did this on a "problem" iMac G5...and a new PRAM battery solved the problem. This iMac could very well have something more serious wrong with it.

Just curious...does anything happen when you turn this iMac on. For example...does the hard drive spin up at all?

- Nick

- Computer slow, too many "beachballs", read this: Beachballs
- Computer seems slower than it used to? Read this for some speedup tips: Speedup
- Almost full hard drive? Some solutions. Out of Space
- Apple Battery Info. Battery
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nowthen2k6

 
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Quote:
Originally Posted by pigoo3 View Post
Nice try! I did this on a "problem" iMac G5...and a new PRAM battery solved the problem. This iMac could very well have something more serious wrong with it.

Just curious...does anything happen when you turn this iMac on. For example...does the hard drive spin up at all?

- Nick
Sometimes it all comes on fine and boots to osx no problem.

When it doesn't start up, its totally dead, no chime, no hard drive activity, nothing except LED1 lit on the logic board.
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pigoo3

 
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Quote:
Originally Posted by nowthen2k6 View Post
Sometimes it all comes on fine and boots to osx no problem.

When it doesn't start up, its totally dead, no chime, no hard drive activity, nothing except LED1 lit on the logic board.
What's the history of this iMac G5? Something you had for a while...and was running fine previously...and now has problems? Or did you just get it...and it has never run as it should?

- Nick

- Computer slow, too many "beachballs", read this: Beachballs
- Computer seems slower than it used to? Read this for some speedup tips: Speedup
- Almost full hard drive? Some solutions. Out of Space
- Apple Battery Info. Battery
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harryb2448

 
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Sounds like a faulty power supply.

Have a look at this and see if it helps:-

Apple iMac G5 Power Supply Issues and DIY Apple Repairs | According to Jim

Hang on to those original install discs like grim death! Using OS X.7 or later make a bootable USB thumb drive before running Installer!
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nowthen2k6

 
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Quote:
Originally Posted by harryb2448 View Post
Sounds like a faulty power supply.

Have a look at this and see if it helps:-

Apple iMac G5 Power Supply Issues and DIY Apple Repairs | According to Jim
Cheers, that was helpful , I was always more inclined in thinking it was probably the psu. I looks a bit beyond me to fix the psu, so a new one looks favourite. thanks again.
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