it-solve
Member
Got this iMac with customer DIY replaced SSD, since then it turns on with no backlight.
Unlike the Macbooks, it doesn't seem to have backlight boost line on the main connector, only plain PP12V_LCD line. Not sure how bent pin on 12V lcd line can cause backlight failure. J8200 cable seems intact.
I reversed the screen connector and ensured that it has no short on the pins to the LCD.
Its very hard to test with screen on.
No short on any of the lines on the board or screen.
PP12V_LCD = 12V
Although no short on BKLT_BOOST_1
BKLT_BOOST_1 = BKLT_BOOST_2 = 0V (connected screen)
LED_RETURN_X = 0.2V
PP12V_S0_BKLT_PWR = 0V
F8100 intact
Randomly measured around U8100, no shorts
Unlike the Macbooks, it doesn't seem to have backlight boost line on the main connector, only plain PP12V_LCD line. Not sure how bent pin on 12V lcd line can cause backlight failure. J8200 cable seems intact.
I reversed the screen connector and ensured that it has no short on the pins to the LCD.
Its very hard to test with screen on.
No short on any of the lines on the board or screen.
PP12V_LCD = 12V
Although no short on BKLT_BOOST_1
BKLT_BOOST_1 = BKLT_BOOST_2 = 0V (connected screen)
LED_RETURN_X = 0.2V
PP12V_S0_BKLT_PWR = 0V
F8100 intact
Randomly measured around U8100, no shorts