A1419 Backlight

Got an A1419 27" iMac with broken glass and no backlight. Before I order the screen I wanted to test the logic board to make sure the correct voltage is coming to the screen. What pin should I test to check the voltage and what should it be?
 

dukefawks

Administrator
Check on BKL connector J8320 between pins 1-4, 2-5 and 3-6. Expect 30-40V there. Inspect both cables for damage and do a PRAM reset. Was this messed with before?
 
Sorry I don't have board-view or schematic for this so i flying blind.

I'm assuming that connection is the six pin one to the right of the 30 or so pin. While imac was on and screen plugged in I checked each pin to ground and only pin 4 had 1v. the rest did not have any voltage going through.
 
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dukefawks

Administrator
I said between pins, the LEDs have no ground reference. Did you do a PRAM reset? Was this messed with? Why is the LCD cracked, this should not affect backlight.
You have checked the prices of the LCDs and want to spend $$$?
 
I did both between the pins and put the common on my ground. no voltage either way. imac was not messed with original seal was intact. preformed pram reset. no difference. according to customer glass was cracked long ago. i gave estimate of 600-700 to fix (incase either have to replace logic board or lcd).
 
I don't have board view for this one. could you pm me a copy? i checked online and everyone wants me to buy one. if not i can buy it
 
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