MacBook Pro unibody 17 2009 board repair (green light, no fan spin)
The board that coffee damage but no visible damage on the pcb. It stopped working after coffee got on the keyboard and I got it years after this. I noticed that it would only boot somewhat buggy if I help it upside down. I cleaned everything including the entire keyboard in 99% isopropyl even though I saw no water damage on the pcb itself (some isopropyl got into the screen... and RIP coating on the keycaps) and reinstalled OS X. It worked fine but the keyboard was broken with only a few keys with weird inputs working. An USB keyboard acted the same way. Since I didn't have a charger that I could keep at the time it just sat there for like a year. Now I got the original charger too and it doesn't boot anymore. The charger has a green light but when I short the power pins on the mainboard nothing happens.
I measured a bunch of voltages but I am a noob with this :c the capacitor that seems to usually cause this (C7771) is fine. Here is some stuff I found out:
PP3V3_S3_FET 5.3mv - seems to be created by Q7910 (part name FDC638P_G). On pin 3 P3V3S3_SS is 3.320v and on pin 4 PP3V3_S3_P3V3S3FET is 3.336v. If I understand it correctly these two are the input voltages and pin 1 2 5 and 6 are all the output of PP3V3_S3_FET which is only 5.3mv. Could this be my problem and I have to replace this?
I think I found the part on ebay but without the _G at the end. Would that still work fine? https://www.ebay.de/itm/2-pcs-FDC638P-Fa...
edit: Ok I just found out how a mosfet works. So pin 3 is the gate and pin 4 is the source? And currently the voltage on pin 4 is a bit smaller than on pin 3 which means the mosfet doesn't let power through? So... should this be in this state right now or should I look further? If I should look into this is pin 3 too high or pin 4 too low?