2 bad 24" iMacs in a row with near identical issues

[retta283]

I know this is early Intel, but I figure people in this subform will have a better idea of these problems than posting in the main iMac forum.

I found a 2007 24" iMac near the beginning of the year, and it was very messed up. The screen was horrible, quite yellow and very uneven color. Almost appeared to have blotches or stains in the panel that were very dark yellow. The corners were very dark relative to the rest of the display. It also had horrible image retention, if I kept a browser up for a few hours I'd have a sharp line in my screen where the window edge was for a long time after. It only took a few minutes for a window to be retained in the screen though.
It also ran extremely hot and the HDD was starting to fail as a result of burning up.

Fast forward to July, and I picked up a 24" 2006 white iMac. To my amazement, it was also riddled with these problems. Same exact issues with the display, yellowed, uneven with stained appearance, dark edges, horrible image retention. They might as well have been the same panel. It also runs extremely hot and HDD also appears to be in poor health due to heat. I was extremely surprised by this, I didn't expect to get two fairly different machines with identical issues in a row.

Now, what I'm wondering is if this is a problem with all 24" iMacs. I have read a lot about the 2007 models have yellow/uneven screens but no image retention or major heat problems. I haven't heard of any issues with 2006 24" models other than the humming sound they make at low brightness. I have both of them still but no OSes installed on either, but I'd like to see if the LCD panel is the same model which may narrow it down. The 2006 has the 7600 GT, if it matters.

 

[jmilan0302]

I'm pretty sure the image retention is just a feature of IPS screens, especially those old ones. I had an Mid 2010 iMac with the same issue though much less extreme.

 

[Amethyst1]

I'm pretty sure the image retention is just a feature of IPS screens, especially those old ones.

Neither my acrylic ACDs (2002-2004) nor my T221s (2003-2005) exhibit image retention as extreme as described by the OP.

 

[1042686]

The 24” white imac Gpus are prone to failure. I’ve not experienced the yellow screen although replacing them is easy. The gpu is a bit more labor intensive but still easy compared to say a macbook tear down. They all run hot & need A periodic Disassembly and deep cleaning out with compressed air. You’d be surprised with how much dust, animal dander n’ hair & crap that gets stuck in there and never leaves.

while it’s apart I recommend a clean and repaste Of the cpu and gpu. Be prepared to remove melted gross thermal pads off the gpu and replace them with new ones or copper shims if you can get the right thickness. They all run hot though - no way around that. Smc fan control is a good choice to ramp up system fan speeds while doing Cpu/gpu intensive tasks.

 

[retta283]

It's certainly possible that the GPU is involved in the image retention on the white one, but it seems really odd to me. I've heard that the 7600 GT is much less likely to fail than the 7300 GT, but it is possible. I have noticed some corrupted graphics in games which made me curious.

 

[1042686]

It's certainly possible that the GPU is involved in the image retention on the white one, but it seems really odd to me. I've heard that the 7600 GT is much less likely to fail than the 7300 GT, but it is possible. I have noticed some corrupted graphics in games which made me curious.

Screen Artifacting in 2D games & YT & Screen retention while in 3D game is exactly how my 24” presented prior to the gpu failure.

I baked it and got about 6 months Additional use before it went Kaput for good. The Price of the 7300gts make repair prohibitive.

 

[retta283]

Screen Artifacting in 2D games & YT & Screen retention while in 3D game is exactly how my 24” presented prior to the gpu failure.

I baked it and got about 6 months Additional use before it went Kaput for good. The Price of the 7300gts make repair prohibitive.

For me, on both of these systems I get image retention no matter what I'm doing or what my system temps are. I plan to pull the panel model numbers from both systems to see if they're the same or not. If they are, defective panel most likely. I'll probably part them out afterwards.

 

[retta283]

Just an update on this, I discovered that they both have the same panel, the only distinction is that one is matte and one is glossy. So I think I found a defective row of panels. I did some researching too here on the forums and elsewhere and this was actually a fairly common issue on 24" iMacs from 2006-09 so this issue is definitely present.

Whether high temps relate or not I am not sure, as the two I have run blazing hot, even when the fans are maxed they're about equal with my 2010 iMac running at Apple's default RPMs. Posting this mostly so other people can see this if they have the same issue.

 

[1042686]

I can tell you that I ran my 24” without a screen for about 3 months and it ran
Without issue so certainly IMO the heat issues arise from the lcd. The second a new one goes in, temps jump up and cooking ensues.