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Model A1418 / Late 2012 / 2.7 & 2.9 GHz Core i5 or 3.1 GHz Core i7 Processor

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Unit turns on then abruptly shuts off during mid-chime

My troubleshooting with this issue thus far….

  1. With everything connected, when turned the unit on, it starts to chime and then abruptly shuts off.
  2. If I remove the display, the unit turns on and chimes and stays on. Given that, I decided to try a different display but had the same issue.
  3. In terms of the display, If I remove the LVDS cable only and leave the black cable plugged in, the unit turns on and chimes and stays on.
  4. In terms of the display, If I remove the black cable and leave LVDS plugged in, the unit returns to the same issue, i.e. shuts-down during chime.
  5. The Power LED lights on the motherboard all act normally with the display removed.

So not sure what is going on. Given the test plugging in the LVDS cable, it sounds like it might be an issue with the video controller on the motherboard but looking for advice in terms of anything dealing with this kind of issue.

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Not sure what you’ve tested here as it’s conflicting. Looking at the logic board with the display disconnected you should see the first three onboard diagnostic LED’s

Block Image

If you plug the display cables in and after restarting the system all four LED’s should light.

Tell us what you see

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Thanks for the help.

Based on what you asked me, here are the results.

1. With the display disconnected, when I plug-in the power cable, LED#1 turns on solid. When I press the power button, the unit chimes and then LED#2 and LED#3 turn on solid. LED#4 stays off.

2. With the display connected, when I plug-in the power cable, LED#1 turns on solid. When I press the power button, the unit starts to chime and then abruptly shuts off. At this point. none of the LED lights are on.

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The LED's are telling us your logic board GPU logic is OK, But it does appear your display its self has a problem!

Did you insert the cable correctly? You may have damaged the data cable or socket and/or the power socket and the its cable.

Can you give us a bit more info on what happened. Post some pictured of the connectors and cable ends so we can see 在已经存在的问题里加入图片

You may need a new display assembly.

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Sorry but I mentioned in the original post that I thought it was the display assembly but I tried a new one and still had the same issue. Unfortunately, the replacement panel did not come with a new LVDS cable so I had to move it from the old one. Is it possible that cable is bad?

Basically, machine was in service working when this issue started. So this was not as a result of doing any prior work on it.

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Wondering if its possible that the Power Supply is shorting out when the display is attached? Anyone seen this kind of behavior?

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jstephen 将永远感激不已
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