Working on an 820-3115 that had moderate liquid on top edge (as usual). Cleaned all liquid, replaced affected components, found 3v3_s5 shorted. Repaired short, got fan spin. Popped the board into a known-good test case, and it has the following symptoms:
1. Powers on, front LED comes on as normal (and goes off as normal--will turn on if I close the lid)
2. No chime
3. Optical drive cycles normally, as if it's powering up
4. LCD turns on--backlight turns on, but screen is black, so no video data.
5. Does not respond to PRAM reset. Nothing. Checked to make sure it wasn't EFI locked, and it isn't. Will respond to SMC reset.
I'm about to head out for the day (already stayed an extra hour working on this one), but will check VCORE and BIOS area in the morning. I wanted to go ahead and post, though, because would the LCD turn on (with backlight, black screen, no image) if VCORE and BIOS were not good? I think they will both turn out to be fine, but wanted to get an idea of what to check next. Thanks as always for any help in advance.
1. Powers on, front LED comes on as normal (and goes off as normal--will turn on if I close the lid)
2. No chime
3. Optical drive cycles normally, as if it's powering up
4. LCD turns on--backlight turns on, but screen is black, so no video data.
5. Does not respond to PRAM reset. Nothing. Checked to make sure it wasn't EFI locked, and it isn't. Will respond to SMC reset.
I'm about to head out for the day (already stayed an extra hour working on this one), but will check VCORE and BIOS area in the morning. I wanted to go ahead and post, though, because would the LCD turn on (with backlight, black screen, no image) if VCORE and BIOS were not good? I think they will both turn out to be fine, but wanted to get an idea of what to check next. Thanks as always for any help in advance.