Chosen Solution
Hello Guys, Was wondering if someone could lend some expertise into this problem. I have a late 2008 MacBook Pro unibody 15.4 and the backlight is not working. I can use external monitor and I can see all images when shining a bright light at the screen, but no backlight. This is what was done so far; 1-replaced the logic board twice, same problem no backlight 2-replaced the LCD screen no backlight 3-I now have a third logic board and no backlight I really don’t think it could be three bad logic boards! Question, could it be a bad LVDS cable? Any help would be appreciated.
Your LCD or LCD cable is &&^&^$^ up the boards. You’ll need to give an 820 number for your logic board(NOT 820-2565 THIS IS A DCIN BOARD NOT A LOGIC BOARD) so we know what backlight circuit yours uses, and so you can buy a schematic and a boardview online somewhere so you can follow along with our advice. Start by measuring voltage on pins 38/39/40(they’re all tied together) on the LVDS connector, and see what you get. Also measure with LCD cable plugged IN, and NOT plugged in, in diode mode on your multimeter, with red probe on ground, black probe on pins 38/39/40, and provide measurements here. 0.519-0.546 means healthy. 0.2** means bad LED driver. 0.00 or 0.019 means there is a direct short to ground in either the connector, or the LCD/LCD cable itself. Resistance is NOT diode mode, so figure out how to set your multimeter to diode mode.
