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SkippyThorson
Sep 30, 2012, 10:25 PM
Hello all my PowerPC brethren. :) I have a project from a family member here.

I was given an iMac G5. It has a 1.6ghz procesor, 512mb of ram, an 80gb HD and a Combo drive. It used to be an education machine at a college before he bought it, and now I'm its new caretaker.

The machine makes the boot chime and will accept and eject CDs, but the screen displays nothing. I was wondering what could cause this, and how much should I expect to spend on repairs? Is there a checklist of things I can look for?

I don't want to go crazy on a broken PowerPC, but if I can get it working for cheap, it would be a great work computer. :)



havokalien
Sep 30, 2012, 10:31 PM
First is try reset the motherboard. There is a button on the motherboard when you pull the back cover off to reset it. While turning the unit on there are lights that will tell you if the GPU failed or not. Do a search in apple support for it should bring up the test and reset procedure. If all that is fine then the screen is the issue. So long story short motherboard or screen needs replaced unless it comes back on after reset.

Good luck.

4JNA
Oct 1, 2012, 08:24 PM
agree with the reset, but would also remove and re-install the ram (power off/cord removed) if you have the back off. those were wonderful how the back popped off after loosing the 3 gizmos on the bottom. also look at the capacitors near the bottom where the power supply plugs in to see if any of them are 'bulging' out or up. should be shiny silver and flat if all is well. bulging is the sign that they are failing, and that was one of the problems these had the recall for long ago.

i think i would also use the external video adapter to external monitor to see if anything is showing up at post. could be an easy way to rule out logic/video problems.

if it is just the lcd, they are fairly easy to replace and can be found used/working pull on ebay. best of luck.

MiniMi
Oct 3, 2012, 08:46 AM
If it powers up, checking the RAM is kinda useless. My opinion, if you aren't getting anything on display try putting a different display card in.

666sheep
Oct 3, 2012, 11:41 AM
99% it's graphics chip. This model uses FX 5200 Ultra 64MB, that same as in last iMac G4 and 12" PB. If it would be another iMac G5 model, I'd search elsewhere but if it's model with 5200 + symptoms you've described = graphics card failure. Only fix is to replace this chip (hard to find and requires BGA soldering equipment) or whole logic board.

4JNA
Oct 3, 2012, 02:43 PM
If it powers up, checking the RAM is kinda useless. My opinion, if you aren't getting anything on display try putting a different display card in.

well lets see...

won't post. ram is part of the post, the contacts develop resistance due to corrosion over time which can be fixed by removing and re-seating...

unless the post is completed with no errors, the video will not be intialized which would mean no display even if there are other faults...

the display card in these models is part of the logic board (mobo for you pc posters) and can't be replaced unless you have a reflow station at your disposal...

agree with 666, almost a slam dunk on the video card. just always hoping for something else and easier to fix like caps on the logic board and in the power supply which was the cause of a massive recall several years ago. then there is always the unseated connectors, loose or dirty connections, defective lcd, failed display inverter, etc.

fix a couple hundred of these, then let me know. happy to listen, i am always willing to learn something new.

just trying to help the OP with the issue stated. thanks.

SkippyThorson
Oct 3, 2012, 06:47 PM
First off, thank you for all the replies everyone. I've had a lot of diagnosis ideas.

Alright I think I'm getting somewhere. Did the SMU reset , and only LED 1&2 lit. After a second time, LED 3 lit and I got some snowy colored fuzz on the display. After a few more times, the Apple logo and loading wheel showed fairly distinct through the fuzz. I couldn't get it any further than that.

Signs point towards a logic board replacement any way it goes, right? This is the 1.6ghz non-iSight model, if that helps anything.

666sheep
Oct 4, 2012, 06:45 AM
Signs point towards a logic board replacement any way it goes, right? This is the 1.6ghz non-iSight model, if that helps anything.

Yep. Good news is that you can buy 1.8 GHz board (slight CPU upgrade, I'm not sure if even 2.0 ALS logic board wouldn't fit?), bad news is that it still will have that same FX5200.

SkippyThorson
Oct 4, 2012, 07:50 AM
Yep. Good news is that you can buy 1.8 GHz board (slight CPU upgrade, I'm not sure if even 2.0 ALS logic board wouldn't fit?), bad news is that it still will have that same FX5200.

Really? I never knew that. So different boards' processors have no other impact that differentiate the boards themselves? Huh.

4JNA
Oct 4, 2012, 10:27 AM
ALS board won't fit. some of the mounts don't line up. i've tried...

the 1.8 non ALS board works fine, and is a decent upgrade if you can find it.

difference between the 1.6 and 1.8 was cpu speed of course, but the 1.6 front side bus was clocked at 533mhz and the 1.8 was 600mhz. both 3:1, just moving stuff fasted due to cpu base clock speed. everything else in the system (power supply, drives, etc) was identical. straight up swap.

the drive connection was SATA I, but most of the current SSDs work fine and really speed these things up.

owned several, repaired tons, like them a lot... except for the often dying non-replaceable video cards anyway... best of luck.

666sheep
Oct 4, 2012, 11:59 AM
ALS board won't fit. some of the mounts don't line up. i've tried...


Shame. It would be great upgrade due to CPU and R9600 128MB :(