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jpcoelho
Apr 12, 2013, 05:11 PM
Hello!

I have a 1st generation iMac G5 (17 inch, 1.8 GHz) which does not boot up...

it chimes, the gey screen with Apple logo appears (with artifacts) and it freezes before completely loading the OS... I have reviewed some of the threads regarding iMac G5 issues, but none seem to describe this issue completely... I understand that common causes are either the caps or the GPU, just wanted to check if someone has had these exact symptoms and what the cause was...
here are some stills of what the boot screen looked like:
http://imageshack.us/a/img201/4747/img0150yp.jpg
http://imageshack.us/a/img833/729/img0149ve.jpg
http://imageshack.us/a/img835/7227/img0151oa.jpg

thanks in advance...



rjcalifornia
Apr 12, 2013, 06:08 PM
Bad Hard Drive? System error?

MisterKeeks
Apr 12, 2013, 06:25 PM
Bad Hard Drive? System error?

Doesn't sound like either of those.

eawmp1
Apr 12, 2013, 06:37 PM
Open it up. It was easy to do on this iMac. You can visually examine the capacitors (they bulge out if bad) but my money is on the GPU. Can you boot off a system disk?

jpcoelho
Apr 12, 2013, 06:49 PM
Thank you all for the input!

Doesn't sound like either of those.

You are right, the boot disk was actually my powerbook in target disk mode... the question mark folder appears, it then recognizes the powerbook drive and starts to boot, until it freezes...

Open it up. It was easy to do on this iMac. You can visually examine the capacitors (they bulge out if bad) but my money is on the GPU. Can you boot off a system disk?

I did open it up to examine the caps, but found no obvious culprit... there is one questionable cap that may be somewhat bulged, one of the four 1000uf 16v caps.

I may try to change this cap first, to see if that fixes it... if not it will probably be the GPU, or is there some alternative cause I am missing?

chrfr
Apr 12, 2013, 07:03 PM
I may try to change this cap first, to see if that fixes it... if not it will probably be the GPU, or is there some alternative cause I am missing?
If you're in there, change all the caps. If one is bad, the others are from the same batch and will likely follow. What you're seeing on screen looks like what I saw on another old G5 iMac when the caps went.

jpcoelho
Apr 12, 2013, 07:09 PM
If you're in there, change all the caps. If one is bad, the others are from the same batch and will likely follow. What you're seeing on screen looks like what I saw on another old G5 iMac when the caps went.

Ok, good to know... hopefully it will be just the caps, I don't really want to have a go at the GPU with the heat gun!

666sheep
Apr 13, 2013, 12:24 AM
More likely it's the GPU.

AlphaDogg
Apr 13, 2013, 12:26 AM
Lol capacitators

Nameci
Apr 13, 2013, 02:12 AM
I had that same thing happened to my quad.

The culprit, memory. I have to open up my quad G5, remove all the dust bunnies and reseat all the memory sticks.

Hth.

jpcoelho
Apr 14, 2013, 10:28 AM
Thank you all for the input...

I will therefore tackle this one from the easiest solution to the hardest:
1- check the RAM modules (thought I believe they are both working properly)
2 - replace Logic Board Capacitators
3 - if nothing else works, try to reflow the GPU with a heat gun
4 - if not even that works, see if one of these (http://www.ebay.co.uk/itm/110942534244?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649) may work and make it an iScreen ;)

cheers!

vrodion
Apr 19, 2013, 08:20 PM
GPU ! my G5 has the same issue
replaced all capacitors, bur stil the same nvidia issue
tried to re-heat gpu- dont work

PowerPCMacMan
Apr 19, 2013, 08:26 PM
GPU for sure.. sounds like the iMac is overheating or there is the possibility of your capacitors leaking onto the GPU chip which could be causing this.. or if not that, then the GPU is starting to go up and the only way to fix that is a new logic board..

At that point you can decide if its worth it.. Personally, the iMac G5's had so many problems that many just replaced them with Intel iMacs.

Here are some sources for replacement Logic Boards:

www.applecomponents.com
www.hardcoremac.com
www.macpartsonline.com
www.mac-pro.com

Good Luck..