Backlight shorted inside display assembly - pls help confirm diagnosis
I have a Macbook Pro with an 820-00850 motherboard. It's been dropped a few times and had some liquid spills in the past. Recently the screen went black, heard a sizzle-pop! and smelled freshly cooked IC wafting from the lower assembly. The motherboard seems to have suffered minimal damage. The only blown component is a 402 (1005) smd chip that is apparently a secondary fuse of some sort. It's not the main backlight fuse and doesn't appear in my boardview or schematic. It's also vaporized so I can't tell exactly what it was. Pictures below.
If anyone knows what this mystery fuse was I'd be thankful for the info!
Whatever it was it blew fast enough to protect the rest of the board. With the LVDS connector unplugged the machine boots and works with an external display. However:
- when the LVDS connector is plugged in PPVOUT_S0_LCDBKLT is a dead short to ground from the the test point just past the vaporized fuse.
- Unplugging the LVDS connector from the t-con board and LCDBKLT measured at the same test point as before is no longer shorted.
- Measuring from the display connector on the t-con board (J0200) again shows LCDBKLT (I don't have schematics for the t-con so I don't the proper alias at this point but it's still the LCD power line that is supposed to carry around 44V) shorted to ground.
- Removing the small backlight connector on the right of side of the t-con board (J0803) opens the LCDBKLT line on J0200 but VLED on J0803 is a dead short to ground.
I'm not a Macbook expert but to me this implies that it is the LED string itself that is shorted to ground and not anything on the t-con board.
Can someone with more experience with these things either confirm this diagnosis or suggest where I may be overlooking something important?
I'm operating under the assumption that I need to find a replacement display assembly to fix this problem. I'd hate to spend the $'s to do that and then find out there may be something simpler that might be wrong.
Thanks in advance for any help!