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

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Why does display look posterized?

Until the hard drive failed, I've had zero problems with my Apple refurbished iMac Core 2 Duo 2.16 20" (Sept. 2006 - FA589LL/A - EMC 2118). After removing the drive,  the desktop/photos look like I've applied a Photoshop posterized effect (see below link).  There is also a slight pink cast to the menus. Please note:  there are no lines, weird pixel defects, dead pixels, or any performance issues.

Troubleshooting: I do not have an external display to test it, but a screen shot shows no defects (see below link).  I've checked the contrast setting under Universal Access, zapped the PRAM and the Apple Hardware Test reported "No trouble found." The first three diagnostic LEDs are on and not flickering.  An Apple Genius did their proprietary Hardware Test, and again no trouble found.   When I jokingly handed him my Torx 8, he politely declined. He said Apple no longer fixes these models, and it would be best to sell it off for parts. That's really a shame because it's such a solid machine.

Has anyone heard of this issue before? For example, if I could honestly say it is most likely a bad cable or wire, then perhaps I can get a better price for it from someone who repairs and resells IMacs?

Posterized desktop:

Screen shot:


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Check your System Preferences:Display-Color (ensure that "millions" of colors are enabled-Mac OS X 10.2, Mac OS X 10.3, & Mac OS X 10.4 I think).. try to calibrate the uint.

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Thank you, machead3. I did ensure "millions" of colors, and recalibrated while running off my cloned hard drive, OS X 10.5.8. Just to be sure, I tried calibrating it again. I also see it while booting off the original system disks, OS X 10.4.7.

It doesn't seem ethical that there is risk in pulling a hard drive, something that is literally expected to fail. It would be like ruining your car after changing the oil.


You can replace the HD - just follow the appropriate guide.


Replacing the hard drive would fix the display?


Don't know - he seems to think that it's related to his HD, and that there's some sort of risk to replacing the HD... there isn't.


I'm sorry if I was unclear. The hard drive removal was noted to isolate when the damage was done. Prior to its removal, the machine and display worked perfectly booted from its external clone.


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Well, sometimes the contrast is changed without people knowing it. Like... say when your cat lays on your keyboard *cough*. Try the Universal Access app in System Preferences (either there or through Displays) and slide the Contrast slider completely to the left.

You can also use she shortcuts Ctrl-Option-Command-, (a comma, there) to turn down the contrast, or Ctrl-Option-Command-. (a period, there) to turn it up. Been there done that. Good luck.

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Ben will be eternally grateful.
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