iMac starts up, chime heard, screen is black, ext. screen no signal
My mac is 20", 2.0 GHz, ATI Radeon HD 2400 XT
A1224 (EMC 2133), Model ID: iMac7,1
After a lightning strike, screen stopped working.
Here are symptomps:
mac boots up, chime is heard. fans, hard drives are heard. it is working as you can hear volume change and other button presses, I can also put it to sleep. All in all, fully functional.
opened it up: three led are on, the fourth is not.
no visual damage, as I can see. all cables seem well connected.
tried external display via mini dvi adapter, but I get no signal. unfortunatelly, I did not have sharing set up, so I cannot remote connect to it and check screen sharing.
Now, I am thinking of replacing video card or logic board...
I think it is the video card, because, I think, if the logic board would be broken, I would not be able to hear all the sounds and have the mac running. Right?
Want to ask what everybody thinks?
I want to follow up with this thread.
If anyone has the same imac, let me tell you that YOU DO HAVE a separate video card. I opened my imac and found it to be EXACTLY as this guide iMac Intel 20" EMC 2133 and 2210 Video Card Replacement
I don't know why machead3 thinks it is soldered. Maybe on others it is soldered, but surely not this one.
I replaced my motherboard with a working one, and it did not solve the problem of my black screen, so I returned the motherboard. I will order the video card from ebay and will try to replace it.
I hope it works.
There is no video card to replace, you'd have to replace the entire logic board... the #4led means that your video card & display are(or in your case aren't) communicating. Also the fact an external display does not work tends to point to the VGC(VPU) as being at fault. Maybe your homeowners insurance will pay for repair or give you something towards a replacement machine.
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