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820-2849 missing PM_SLP_S4_L and PM_SLP_S3_L

peterfixit

peterfixit

New member
820-2849 missing PM_SLP_S4_L and PM_SLP_S3_L
I came to this from testing power rails, all s5 present all s3 missing
visual inspection reveals nothing except for cum stains around the backside usb connectors
r5222, r5223, r5012, r5044 all discolored
the rest looks fine, board was ultrasonic cleaned after initial inspection
 
peterfixit

peterfixit

New member
SMC_ADAPTER_EN is missing
(replace/reflow smc?)
loads of liquid
to the right of the smc
u7000 area
L9499 area
u9330 area
 
peterfixit

peterfixit

New member
replaced q5480 r5481 r5482
ran wire from rin 1 R5481 to pin 4 Q5480
replaced Y2605
I have a genuine 85W charger for both magsafe L and 2
ppbus 1.3V
 
D

dukefawks

Administrator
Pfff you are measuring SLP_S4 while PPBUS is not even there? Why?

Resistance to GND on PPBUS? Resistance between pins 17/18, 27/28 of U7000?
 
larossmann

larossmann

Administrator
Staff member
PPBUS_G3H is what is used to create PP3V3_S5 which is the voltage line the PCH uses for all of the 3.3v logic signals such as PM_SLP_S4_L. Fix PPBUS_G3H first!
 
peterfixit

peterfixit

New member
clarification, on intake ppbus was present, now its not
resistance to ground ppbus@F7074 0.8k
resistance between u7000 pin 17/18 3ohms
resistance between u7000 pin 27/28 20ohms
 
larossmann

larossmann

Administrator
Staff member
that's 800 ohms to ground. It should be way higher. That is going to be a crappy short to find, but I would start by injecting voltage and seeing what heats up. Can you remove F7040 and see what side the short is on?
 
peterfixit

peterfixit

New member
short is on the u7000 side, pin 1
ive removed c7040 and c7045
dc power supply only pulling 0.031A
pulled off q7030 and q7035
put heat over u7000 and it exploded
replaced u7000 and everything else I removed
short to ground on ppbus is gone, now strange behaviour
when I plug in the charger it starts at 13.5volts and stays for like 10 seconds and then drops to 2volts
---------------edit-------------------------
pad 17 of u7000 missing, ran wire from pin 17 u7000 to pin 1 c7050 now ppbus is a steady 12.3volts

SMC_ADAPTER_EN is now 0.896 volts
 
A

aprendiz

Moderator
SMC is not working, check SMC_RESET_L if it is ok could be crap under SMC (do a reflow) or dead SMC (replace SMC)....... .
 
peterfixit

peterfixit

New member
anyway have to put a pin in this until I get an smc stencil, I just received my flux from louis so probably wont be ordering a stencil from him for awhile
 
nate8organic

nate8organic

New member
You do not need a stencil for replacing the smc. if you take the smc off super clean and re seat the new one super clean you can do it with out a stencil. i do not have a stencil and i do all smc replacements free hand. no troubles other than having to take it of and clean it up and putting back on as the balls sometimes fuck up. i have even replaced smcs with no balls on the board or the smc chip and still successful. really i have never seen anyone else do it like that but it works well for me and takes much less time than messing with a stencil getting the balls perfect and then seating it. give it a try if you like it Thumbs up if not use a stencil.
 
peterfixit

peterfixit

New member
no, just no. i dont do anything super clean. ive become really good at reballing, each chip only takes 1-2 minutes
 
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