2008 iMac 24” Restoration Journey

KingDingus

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Jan 16, 2022
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Finally found a Facebook Marketplace project to tackle.
10 bucks! Sold as “parts only.” Previous owner claimed the GPU bad.

I’ll post my progress here.
 

rikerjoe

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Oct 31, 2021
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I have one of these, an iMac8,1 (24-inch Early 2008) with an Intel Core 2 Duo running at 2.8 GHz that was our family’s daily driver until each member moved up to individual MacBook Airs. Its latest official macOS is El Cap, but recently I used one of DosDude’s patchers to put Catalina on it. Runs great under Catalina. Mine has the ATI Radeon HD 2600 Pro graphics with 256 MB VRAM. I also installed the max 6 GB RAM in it. I’ve replaced the spinner HD at least once, and soon I plan on replacing the HD with an SSD. Today it serves as the family media server and centralized Time Machine hub, the latter of which works way better for me under Catalina than El Cap.
 
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KingDingus

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Cycled a boot chime every few minutes with a blank screen. Taking apart to diagnose because it was apparent someone had already take a peek inside.
 

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wottle

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Cycled a boot chime every few minutes with a blank screen. Taking apart to diagnose because it was apparent someone had already take a peek inside.
Had the same thing with a 27". Got it to boot once to blank gray screen, then couldn't get anything but a black screen. GPU failures are common, and it appears to often be related to bad solder joints. That's when I found @JDW 's series on YouTube about the iMac GPU bake. It sounds absurd, but it revived mine and it's been kicking for several months with no issues. (You can read about it here: https://tinkerdifferent.com/threads/imac-late-2009-graphics-card-bake-success-story.232/)

I had been told by the owner that they had a "professional" try to fix it and they had been told it was a complete logic board failure (which is an odd diagnosis, especially since the owner apparently had the machine set to auto-login and start playing a podcast on startup, so you could hear the audio playing if you powered on and gave it enough time. Said "pro" also damaged the backlight cable when poking around inside, so I did have to replace that as well.

Best of luck!
 
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JDW

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Had the same thing with a 27". Got it to boot once to blank gray screen, then couldn't get anything but a black screen. GPU failures are common, and it appears to often be related to bad solder joints. That's when I found @JDW 's series on YouTube about the iMac GPU bake. It sounds absurd, but it revived mine and it's been kicking for several months with no issues. (You can read about it here: https://tinkerdifferent.com/threads/imac-late-2009-graphics-card-bake-success-story.232/)

I had been told by the owner that they had a "professional" try to fix it and they had been told it was a complete logic board failure (which is an odd diagnosis, especially since the owner apparently had the machine set to auto-login and start playing a podcast on startup, so you could hear the audio playing if you powered on and gave it enough time. Said "pro" also damaged the backlight cable when poking around inside, so I did have to replace that as well.

Best of luck!
"Professional" has come to mean "someone who does something for a living," instead of the more intuitive definition of "a real expert in their field." You'd think the daily experience of doing something "on the job" would make one a real expert, but such isn't always the case. As is true of Louis Rossmann, the KIND of experience is key. Rossmann appeared on Linus Tech Tips in the past because Linus wanted help with an iMac. In the course of that video, Linus joked he shouldn't have asked Rossmann to come because Rossmann wasn't that much help with the iMac. Why? Because Rossmann fixes MacBooks and iPhones mostly, hardly ever touching iMacs. That's why when people who have little practical experience with certain machines claim that "such and such a fix is stupid and dumb," it shouldn't carry much weight. The bake really does work, and while it doesn't last forever, no repair lasts forever, nor does any product. The bake simply lasts long enough, in most cases, to have been worth the effort. And when you have nothing to lose, it makes sense to try it, especially since it works well for most people who try it.
 

rikerjoe

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Regarding the GPU bake solution, that is targeted to a particular subset of iMacs with specific GPUs in the 2009-2011 era, right? My 2008 iMac shows no signs of graphics problems necessitating a bake. I'm wondering if the blank screen problem that @KingDingus is describing is due to another factor, such as someone previously fiddling in the interior and messing with the screen connection cable.
 
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JDW

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Regarding the GPU bake solution, that is targeted to a particular subset of iMacs with specific GPUs in the 2009-2011 era, right? My 2008 iMac shows no signs of graphics problems necessitating a bake. I'm wondering if the blank screen problem that @KingDingus is describing is due to another factor, such as someone previously fiddling in the interior and messing with the screen connection cable.
2008 to 2011 iMacs have graphics card issues. I know this because many 2008 owners of both the smaller and larger type contact me in the comments section under my YouTube Bake videos and let me know they had a problem but the bake cured it for them.
 

Certificate of Excellence

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GPU issues creep all the way back to the original 24" 2006 white Intel imac and is heat related. In these 2006-2008 designs, the GPU heatsink is right up against the back of the LCD screen & airflow in these even when clean isn't great. When I originally had artifcating and failure on my 24" white Intel imac, the failure reversed itself when I took the screen out and ran it screenless through an external Apple Cinema display I had. Worked fine like this for months before it went kaput for good (the first time). These GPUs are stupid expensive too lol so the bake is an easy & free way to extend the life (lasted about 8 months for me post-bake) while I sourced an affordable replacement and copper shims vs thermal pads. JDW is right that this fix does not last forever and a replacement GPU ultimately carries the same flaw and potential risk of failure. Assuming that KD's imac GPU is the issue and to RJ's point - if it is not something else like the black LCD cable that connects to the lobo (another common failure point when pros get in there jerking around on the lcd), I agree that baking the GPU is well worth the effort - you literally have nothing to lose.

One caveat, I do not know if Apple (foxconn?) used a lead solder because of its lower melting/boiling point, so to be safe, I would not bake it in my food oven in case of cross contamination of lead oxide - also many home oven hoods are vented inside and not out the roof which recirculates that gross vapor into your home. Take the time to bake it in something like a cheap $15 thrift store toaster oven away from the home. Lead free is less of a big deal. I think the worst thing about that is the rosin when it boils is an asthmatic irritant.

Anyhow, best of luck on the repair, KD. I am a fan of these imacs as they are fun to work on.
 
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KingDingus

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There are a couple of fairly priced GPUs on eBay at the moment so I feel the baking experiment is low risk/low cost if it is unsuccessful.

I genuinely appreciate all the thoughtful discourse on the subject as I’m relatively a novice working on these machines.

Thanks again,
KD
 

KingDingus

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Does anyone happen to have a recommendation for a application that assists with creating a bootable USB drive so I can put a fresh install of an OS on this computer?

I’ve tried following directions to do it manually but Monterey doesn’t seem to want to play nice.
 

Certificate of Excellence

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Does anyone happen to have a recommendation for a application that assists with creating a bootable USB drive so I can put a fresh install of an OS on this computer?

I’ve tried following directions to do it manually but Monterey doesn’t seem to want to play nice.
Hmm, I typically use disk utility & format a 8gb + flash drive to GUID, then copy over the dmg you want to install. Reboot-option and select the flashdrive via boot selector and install. IIRC max macOS for 2008 imac is El Cap 10.11 64bit but if you want to beyond that, you can use a patcher.


*Added - here's Dosdude's YT video on the process.

 
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Certificate of Excellence

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Oh you know, I think I misunderstood you. If you are trying to take your imac to Monterey, you can use @Mr. Macintosh 's instruction here. I have not done this myself so linked Mr.Macintosh to this response if you had any other questions.


Good luck!
 
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KingDingus

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Saturday morning update:

After a few cups of coffee and some tinkering I think I have found a solution to my issue.

Goal: Install fresh copy of El Capitan to the 2008 24" iMac

Problem: Downloading El Capitan to a newer machine running Monterey and creating the bootable USB proved to be impossible at my level of expertise. Monterey did not want to unpack and create the .app installer.

Solution: Downloaded El Capitan to older 2013 MacBook running Mojave and utilized MacDaddy Disk Creator to create bootable USB drive.

Outcome: Installation of El Capitan to project iMac in progress.

Other items in progress: Installed new power cable from Amazon. Need to order RAM cover from Ebay. Inspect to determine cause of fans operating at full speed.

Thanks!
 
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KingDingus

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For future reference:

If you are attempting to install from a USB and replaces the PRAM battery it is important to ensure machine time and date has been set correctly.

I used this reference: