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junvaz
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Diagnose Display or Video problem?

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iMac Intel 27" A1312 EMC 2374 i7

iMac powers on and chime sounds, the display can be seen to power on and remains black the entire time, checked with flashlight and nothing is seen.

All of the LED's are lit, I can connect to the unit remotely and share the screen, I checked the system profiler and find that the video card is detected. I find that if I go to the display preferences and adjust the screen brightness you can see the backlight adjust as its supposed to.

I tried reset all settings

I tried re-seating the video card

I tried swapping backlight inverter and LCD with Known good hardware same result

video card is my last step but i just wanted any suggestions before i shell out the cash

thanks

Edited by: oldturkey03 ( ) , mayer ( )

Just an update, after re-checking all cables and connectors I found V-Sync LCD Cable broken in half hidden under the tape, I ordered the replacement and will update when I replace it. (And yes it seems I always end up with video issues even after upgrading...gave the 20" to dad:-) ).

junvaz,

I replaced the cable and still get the same result here is what the system report tells me...I will try any other suggestions, otherwise I will roll the dice and order a replacement video card. Chipset Model: ATI Radeon HD 4850 Type: GPU Bus: PCIe PCIe Lane Width: x16 VRAM (Total): 512 MB Vendor: ATI (0x1002) Device ID: 0x944a Revision ID: 0x0000 ROM Revision: 113-B9110C-425 EFI Driver Version: 01.00.383 Displays: iMac: Display Type: LCD Resolution: 2560 x 1440 Pixel Depth: 32-Bit Color (ARGB8888) Main Display: Yes Mirror: Off Online: Yes Built-In: Yes Connection Type: DisplayPort

junvaz,

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mayer
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MacHale Enterprises

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If the last four figures of your serial number are one of these, then Apple will fix it for free: DHJQ, DHJW, DL8Q, DNGH, DNJ9, or DMW8

DPM1, DPM2, DPNV, DNY0, DRVP, DY6F, F610

http://9to5mac.com/2013/08/16/apple-open...

Edited by: mayer ( )

You don't seem to have much luck with video problems. I take it you replaced your 20" iMac that you replaced the video card on ;-)

mayer,

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Gary
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connect it to a tv and see if you have fully working unit.

if so it is either a fried video graphic part. look it up on ebay they sell them on there because they have a ISSUE with that happening. i would take it to A APPLE STORE AND LET A GENUIS BAR WIZARD TRY AND fix it for free, he might have a used part he will give you. and there you will get a forsure diagnosis

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serviceqdmac
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There is a Quality Program with regards to this model year. However, a test has to be completed by a technician in order to validate the machine. There are two different cards for this model. Only the one card is affected. Did you try external video to see if its in fact the card?

What are the part numbers on the good and bad boards?

mayer,

Don't have those as of yet. This is a new program. I have only run into one issue thus far.

serviceqdmac,

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