iMac late 2013 - LCD Display is dead

[Eccofreerider]

Hi, guys!

I've problem with my iMac. LCD Display shows black screen (no picture at all), external display works correctly through Mini Display Port - HDMI. 4th LED doesn't lit up, only 3 LEDs are lit up.

I've already changed LVDS cable and LCD Display - problem still exists. But if problem is a logic board or graphics - how external display works?

 

[opeter]

The external monitor/display shows the image without problems?

What do you mean with "4th LED doesn't lit up, only 3 LEDs are lit up."? What LEDs?

 

[Eccofreerider]

The external monitor/display shows the image without problems?

What do you mean with "4th LED doesn't lit up, only 3 LEDs are lit up."? What LEDs?

No problems with external monitor.
LEDs I have mentioned are indication LEDs on logic board.

 

[opeter]

This is for the older iMacs, but maybe it can help you:
https://www.ifixit.com/Guide/iMac+Intel+24-Inch+EMC+2134+and+2211+Diagnostic+LED's/7443

https://www.ifixit.com/Answers/View/123092/iMac+wont+start,+only+diagnostic+led+1+on

 

[Eccofreerider]

This is for the older iMacs, but maybe it can help you:
https://www.ifixit.com/Guide/iMac+Intel+24-Inch+EMC+2134+and+2211+Diagnostic+LED's/7443

https://www.ifixit.com/Answers/View/123092/iMac+wont+start,+only+diagnostic+led+1+on

I got the answer for my problem: Blown fuse on the logic board. Have to replace it or replace the logic board.

 

[opeter]

I got the answer for my problem: Blown fuse on the logic board. Have to replace it or replace the logic board.

I am glad you found the problem.

 

[FreemanW]

Which begs the question, what caused the fuse to blow.