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Model A1200 with 2.16 or 2.33 GHz Core 2 Duo processor

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How do I diagnose a dud graphics card

Daughters machine arrived for dad to fix. Won't start. Partner admitted to mucking about with the OS. Re installed 10.7 worked OK. Next day wouldn't fire up again. Reinstalled the OS, and heaps of other software. seemed sluggish so opted for a reboot. Wouldn't start again. Option D at start up shows the curser (moves with mouse) but no options (HD, optical disk or USB). Screen is backlit. Disassemble, clean everything (with vacuum) look for damage with magnifying glass. Put back together, leaving bezel off. Start, option D, same as before. 4 leds light up green, power suply fan can be seen spinning. Can hear HD and optical drives spin up and do the expected thing. Screen is backlit and curser shows (and moves) but nothing else is visible. Tried pressing enter and using arrows to select imagined options, no joy.

Serial number ends with KVGN

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Apple iMac "Core 2 Duo" 2.16 24-Inch Specs

Identifiers: Late 2006 - 24" - MA456LL - iMac6,1 - A1200 - 2111


Dads are so great when it comes to their baby girls ;-) Glad you came here.


well, got a mini DVI adapter and plugged in another monitor. Whatever I tried, no signal. All 4 leds still light up, both discs hum. Holding the option key places an arrow cursor on the screen (and nothing else) which moves around with the mouse. Tried removing and replacing the button battery, removed and reinstalled the LCD checking connections carefully. Will install another HD and see, although little hope now.


With HD SATA cable disconnected from the MB, starting with the option key then gives disc options on screen, although with no HD the CD spins endlessly, now convinced it only needs a new HD. HD hooked up to Ubuntu is now unable to mount. Definitly HD issue. Thanks all for your assistance.


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Sounds more like HD damage than VGU (the MBD appears pooched, except for the repair partition).Connect to an external monitor, if that's working it could be a bad cable/inverter/LCD. LEDs tell you nothing about the HD, only about the power supply and video chain.

LED #3 will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement.

LED #4 will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.

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Thank you, so helpful.

I was suspicious of the HD, having had to reinstall the OS in quick succession. Hooked up to a linux box and it seemed OK. Took it in to the local MAC shop (very helpful people)and they tested and pronounced it fit for purpose also.

Inititial tear down I found a cable hidden under black tape on the LCD board was only partially inserted in its socket.

Will try another HD and thoroughly check the screen connections. Will also research how to connect an external monitor. Probably need to buy yet another cable.


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