Macbook Pro 820-3115 board noob troubleshooting
Hello everyone, first time I ever try to get really down and dirty with troubleshooting to fix my girl's wine stained computerr 
We too broke at the moment to send it for repair/buy new board so I've been swallowing all of Louis Rossmann's videos to the point where he shows up in my dreams. Every night.
Now I think I've cornered the problem somewhat but I'm a bit stumped, and before watching ten more videos that tell me to look for one of the 300 one wire video circuits, I thought I'd ask for help.
So. My findings: computer doesn't turn on. Magsafe green light is on, except if battery is connected. Battery levels on the side button light up only if charger is connected.
The top half of the board seems to get quite hot whenever connected to the magsafe. Which, uh, shouldn't happen right?
PPBUS_G3H has about 1.5V running through it. PP3V42_G3H is fine.
Now the weird thing happening around the one wire circuit:
U6900 seems to be receiving its 3.4V fine, but the U6901 logic gate A and B inputs are not getting anything (zero comma something). Which is damn weird - how can U6901 output anything if it's not getting anything at A and B?Following Louis' videos it seems to be an AND gate and it should be getting 3.4 as well.
Now if i follow SMC_BC_ACOK back from the logic gate to the CHGR_ACOK output at U7000 I'm also not getting anything of course. But at the input to U7000 after the voltage divider (CHGR_ACIN at pin 3 of U7000, or after R7010) I'm getting 3V instead of 4.
After cleaning the wine off rubbing some alcohol (it's a very drunk board by now which might explain things) I don't see any obvious damage. But then again I'm encumbered with a poor selection of tools - a shitty magnifying glass, an analog multimeter with no diode mode and a sewing needle taped to the positive end, insuficient lighting and lack of a trained eye.
That's all I've gathered so far. If anyone has a hint I'd be very very grateful.
We too broke at the moment to send it for repair/buy new board so I've been swallowing all of Louis Rossmann's videos to the point where he shows up in my dreams. Every night.
Now I think I've cornered the problem somewhat but I'm a bit stumped, and before watching ten more videos that tell me to look for one of the 300 one wire video circuits, I thought I'd ask for help.
So. My findings: computer doesn't turn on. Magsafe green light is on, except if battery is connected. Battery levels on the side button light up only if charger is connected.
The top half of the board seems to get quite hot whenever connected to the magsafe. Which, uh, shouldn't happen right?
PPBUS_G3H has about 1.5V running through it. PP3V42_G3H is fine.
Now the weird thing happening around the one wire circuit:
U6900 seems to be receiving its 3.4V fine, but the U6901 logic gate A and B inputs are not getting anything (zero comma something). Which is damn weird - how can U6901 output anything if it's not getting anything at A and B?Following Louis' videos it seems to be an AND gate and it should be getting 3.4 as well.
Now if i follow SMC_BC_ACOK back from the logic gate to the CHGR_ACOK output at U7000 I'm also not getting anything of course. But at the input to U7000 after the voltage divider (CHGR_ACIN at pin 3 of U7000, or after R7010) I'm getting 3V instead of 4.
After cleaning the wine off rubbing some alcohol (it's a very drunk board by now which might explain things) I don't see any obvious damage. But then again I'm encumbered with a poor selection of tools - a shitty magnifying glass, an analog multimeter with no diode mode and a sewing needle taped to the positive end, insuficient lighting and lack of a trained eye.
That's all I've gathered so far. If anyone has a hint I'd be very very grateful.
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