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Q: iMac 21.5 Mid 2011 backlight flashing

Hello,

My iMac 21.5 Mid 2011 backlight is flashing intermitently. What i already tried:

- External monitor: ok (image is stable)

- Reset PRAM

- Reset SMC

- OSX update to latest available

Apple Technician Guide suggests that if the flashing stops when brightness is set to maximum, then the problem might be the vsync cable. However, it still flashes when it is set to maximum. Anyway, i checked the vsync cable continuity with a multimeter (ok) and reseated the connectors, but the problem is still there.

I tried to run Apple Hardware Test and it reported the following error:

4SNS/1/40000001:VGOR-10.484

It means that there is a problem with the voltage of GPU. I decided to go deep and tried the following software:

https://www.bresink.com/osx/HardwareMoni...

It shows that the MXM graphics module voltage is around 10.78 volts. Probably this is what the error code "VGOR-10.484" wants to tell me :-)

I suspect that this voltage should be around 12V. Can anyone confirm? This tool is paid, but i accidentaly bought two licenses... So, if some good guy wants to help me, i can give one license :-)

Cheers!

iMac, OS X El Capitan (10.11.6)

Posted on Aug 9, 2016 8:39 PM

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