You’ll need to checkout the onboard Diagnostic LED’s so see whats happening. Your PRAM battery could be bad if you’ve left the system unplugged from power or use a switched surge/power strip for long periods. If you’ve not unplugged it and you only have a power stip Vs a surge suppressor your power supply may have gotten hit. But I think we are jumping ahead here ':-}
Lets check out the LED’s, follow this guide iMac Intel 21.5" EMC 2308 Logic Board Replacement Follow it to Step 10. Locate the right SO-DIMM holder, just to the right of it you’ll find a strip of black tape which is covering the LED’s.
Here's a breakdown of the onboard diagnostic LED's:
LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty.
LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.
LED 3 - Indicates that the computer and the video card are communicating. This LED 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 - Indicates that the computer and the LCD display panel are communicating. This LED 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.
Lets know what you find.
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댓글 8개
Matthew Rogers replace the video card first before replacing the logic board. Of course only if your model has one and does not have an integrated tures of your boards etc. with your question. that way we can see what you see. 기존 질문에 이미지 추가하기
There should be no reason at this time to replace your power board. It would only confuse the issue for now.
oldturkey03 의
@oldturkey03 - This series has the GPU mounted directly on the logic board: iMac Intel 21.5" EMC 2308 Logic Board
Dan 의
@danj my mistake. I thought this particular model come in two version. One with an Intel with 256 MB of shared memory and one with MXM graphics with 256 MB of dedicated GDDR3 memory. I was under the impression that there were 4 boards for this model
661-5305,661-5306 661-5307 661-5420
My bad. I did not see the proper description in the question/comments and made the assumption that this could be an MXM model since LED #3 is not present on models with integrated graphics whereas the OP mentioned LED #3
oldturkey03 의
@oldturkey03 - No problem, I make mistakes so its always good for someone to double check.
Matthew might be able to swap out the logic board to one of those MXM versions. But, the cost between the logic board and the MXM GPU board would likely push the budget and given the age of the system I wonder if it's worth that investment.
Dan 의
@danj so Matthew Rogers has the Intel version with integrated GPU? Why would there be an LED#3? Well, I am out of this one. Obviously do not know enough about it ;-)
oldturkey03 의
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