Can anyone explain the 4 LED lights for troubleshooting?
imac 21" model no.A1311
Sorry for double posting my problem but I still have not seen a good answer to this. My iMac 21.5" late 2010 is booting only on external monitor. The internal is not recognized and is black. There is no crazy fan blowing and everything except the internal LCD is working.
There are 4 LEDs on the logic board by the LVDS connector
1 - lights up (power)
2- lights up
3- lights up (communicating with LCD?)
4- does not light up
The question is:
Should the LED 4 light up and then go off? I understand from what is posted here that if it is on all the time there is a problem with overheating.
If LED 4 is NOT at all lighting up, where do I start for troubleshooting?
I have changed the LVDS cable and inspected the LVDS connector on the logic board side which looks ok.