Single work

820-2523, Dead

Description

Board seems to have been washed without cleaning off old thermal paste.
Had to leave in denatarured alcohol bath overnight.
Gave the board an ultrasonic cleaner bath.
Board has a resistance of around 8k in the ppdcin_g3h rail when it should be infinite.
Using a regulated lab supply, injected voltage on ppdcin_g3h rail, U7000 got very hot.
Replaced u7000 now machine has green light and turns and starts normally.
Noticed that the machine is not detecting a battery. An X shows up in place of the battery icon in Mac OS.
Won’t turn on from battery.
No shorts found on pin 6 or pins 1-3 of battery connector.
Q7055 seems to be in good working order.
Found resistors R7051 and R7052 with double their value (20ohm instead of 10). Replaced both now read good.
Still no battery detected, magsafe stays with green light.
SMBUS_SMC_BSA_SDA (pin2) of R5280 had no activity when checking with the scope.
Suspecting a defective SMC, took a donor board and removed it using the jovy re-7550 station.
Soldered the donor SMC in place and board now works fine and charges the battery.
Ready to go.

Summary
Created by

ALRC

Completed on

June 6, 2017

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