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No backlight issue all resistors on circuit are good besides R8432 which should be 150k but it's 24.2k. Also I get diode mode on PPVOUT_S0_LCDBKLT 0.50 which might be a shorted Cap? In the past on the same laptop I had C8471 burned but maybe happened again?
I only get till pin 3 & 4 on Q8400. I have another board but lots of parts taken out and not showing properly. No voltage on PPVOUT_S0_LCDBKLT with LCD connected and i tried 2 lcds
"Did you try known good LCD assembly?"
Backlight adjust comes through I2C bus from T-CON board.
"Test in diode mode:
Connect positive probe of the multimeter (red) to ground and touch the test point with black probe.
Sometime (rarely) we need to test in reverse direction."
Lot more information on that thread...
I understand diode mode measurement just didn't know why reverse measuring Yes I've tried known good LCD from another laptop. reverse reading on PPVOUT_S0_LCDBKLT is 0.035 and also diode mode same which was not before...
Depends is backlight out is shorted, or interrupted.
Getting 55V denotes no contact with LEDS strip.
0V can be short, or backlight circuit blocked for other reason.
"pins 15,16,17 0v"
So missing BKLT_EN_R; EDP_BKLT_EN too?
Check R8450-53; strange to get 0V at pins 15 & 16...