realmacmods
Member
Working on a 820-3476. It will boot fully (sometimes it says aloud "to choose english as your language press the return key), but no display via internal screen or thunderbolt display.
Doesn't appear to have liquid damage anywhere. not getting enables on u8330. if i remove u8330 and hot wire the enables the backlight will turn on, and the screen will get power at the connector. HPD 2.5v at r8301. i2c at connector appears to all be there. nothing measurable on the EDP termination resistors, but the resistors themselves are 1M to ground
Pram reset successfully, but no change, same for SMC reset.
known good screen, put a known good logic board in the chassis and all worked.
looks like the enables come directly from u0500 (cpu), so i suspect something isn't happening to tell the CPU to take those high, but i cant figure out what could possibly be missing. Especially given that it boots fully.
Doesn't appear to have liquid damage anywhere. not getting enables on u8330. if i remove u8330 and hot wire the enables the backlight will turn on, and the screen will get power at the connector. HPD 2.5v at r8301. i2c at connector appears to all be there. nothing measurable on the EDP termination resistors, but the resistors themselves are 1M to ground
Pram reset successfully, but no change, same for SMC reset.
known good screen, put a known good logic board in the chassis and all worked.
looks like the enables come directly from u0500 (cpu), so i suspect something isn't happening to tell the CPU to take those high, but i cant figure out what could possibly be missing. Especially given that it boots fully.