Model A1174 with 2 GHz Core Duo or Model A1207 with 2.16 or 2.33 GHz Core 2 Duo

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shards of graphic doom fill the screen

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I've postponed dealing with the display issues for several years by using SMCfancontrol, but am now in the same boat as previous posters. 2.16Ghz white imac A1207, shards of graphic doom fill the screen, over heating happens swiftly, and it just won't run anymore. I've done one take apart and clean out, hoping it would help, but no joy. Trying to locate replacement parts in advance of a deeper look inside, but having trouble finding what I need, although powerbookmedic.com has quite a nice inventory. Wondering if it's the inverter, rather than the GPU. The guide I'm using is here - iMac Intel 20" EMC 2105 and 2118 Repair

Small variances in build from those steps, but nothing too tough as long as you take your time. Reassembly is tricky though, really do stop and get all the freaking tape out of the way, it'll spare you some misery.

- Macgeek

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Macgeek - To start with you should make your own question as this one is quite old (even if it's a similar problem). Can you more fully explain what "Shards of graphic doom" is, I do like the line ;-} Are you seeing odd color blocks {static} or fading areas? You might want to get a temp monitoring program like Temperature Gauge so you can see whats happening.

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Thanks Dan - smcfancontrol does have temp monitoring capabilities, and I'm pretty sure that the cpu fan is no longer working, but now can't get it to boot normally, and need to determine if there's any fixing this imac. Will go start my own question - liked this thread because it's the same model, same issues, and there have been good suggestions, so I hoped the previous posters would respond with what worked.

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Currently, the imac boots up to desktop, but on fully loading the Finder, it self-reboots. Shards of doom continue, broken boxes of grey noise, triangles of smeared pixels from background, thin black lines horizontally. Only 3 lights on board instead of the 4 in the docs; All 3 light as one might expect, and even the third light stays on during auto-reboot. Inverter or GPU or logic board? Anyone?

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Thanks folks, I'm looking at logic boards and thinking that any I buy may have the same issue, so want to try reflowing it. What I'm seeing on youtube is all related to laptops though, and folks are doing them in various stages of disassembly. Does anyone have any info on how far down I need to tear this logic board? For instance - pull off the heat sinks? IR board? Also, since it seems to vary - what's the best practice - pre-heat the oven and put the cold board in there, or put the board in cold and let it all warm up slowly? I've reflowed spots on boards with a blow dryer before, with moderate temporary success - just a little nervous about putting an imac in the oven.

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mugszee, you can not reflow with a hair dryer! Check on here Hair dryer for logic board reflow? for the analyses :-) So we'll have to try and find a reflow profile for the GPU. May take a bit, in the meantime, take a look through youtube. If I remember right there are a few videos about reflow on a couple of G5's, just to get an idea.

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Macgeek - Sorry for taking awhile to respond, had to think this though a bit.

I think you'll need to fix the obvious issues first like the CPU fan. As you can't run the system long enough to run any diagnostics. I would then run Apple Hardware Test (AHT) to see what it tells us.

I don't see the inverter as being an issue here as it just supplies the needed high voltages to power the CFL's.

I do wonder if the graphics board is still reliable after cooking for so long. If its bad it can it be replaced by it's self GPU replacement but getting the correct MXM PCIe 16x NVIDA GeForce 7300GT GPU will be difficult. Leaving you the only other option here of replacing the complete logic board.

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Thanks Dan. Since this is the 20", the GPU isn't replaceable. I had seen some graphic anomalies caused by failing inverters before, but not to this extent. Cleaning off and replacing the thermal paste and blowing all the dust out thoroughly didn't make enough difference to complete a full boot, and the screen still shards up right away. Looks like a logic board replacement, almost not worth it for this model imac. Thanks for your response.

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mugszee, any chance you can post an image of what your LCD shows. I keep thinking a reflow might work for this and it could save you a few $$. Also, any chance you could post the last three of your serial number? that way we could identify this a bit better.

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OT - He has a A1200 2.16Ghz White iMac

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Duh, I guess I should read a bit more or put my glasses on;-). Thanks Dan.

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For this mac, so many parts would probably need to be replaced that it would probably be cheaper to buy a used one off ebay.

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Just trying to find any way to determine if this is related to logic board failure - it needs a cpu fan which is trivial, and if this graphic stuff is due to a failing inverter board, then parts = $50 and it would be worth fixing. Logic board is about the same as another used imac, so not worth it. Are there any specific tests to determine if it's the GPU or the inverter?

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It's an A1207, 20" 2.16Ghz iMac, EMC# 2118, serial - GX9E. I've got a couple of pix of some of the shards. The image also breaks up into blocks of noise, sometimes blocks of color - blue or pink - and most often has diagonals that look like the image has been cut off and then smeared. I'll try to find a place to drop an image so I can link it, looks like I can't post an image here(?)

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mugszee, definitely agree with Dan on here. It most certainly looks like a bad GPU. I guess it is up to you on how to proceed. replacing the logic board would be one way, trying a reflow another, and if nothing else you could always sell it off.

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mugszee - Love your background picture where did you find a hires version of it?

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mugszee will be eternally grateful.
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