Single work

820-2530, Pulsating Green Light

Description

No signs of liquid damage.
With apple original magsafe green light blinks and voltages pulsate. Won’t turn on.
With non-original charger magsafe has green light, wont turn on.
With battery installed and original magsafe connected, no green light and powers on.
With battery only board powers on.
So the system is having problems working from the magsafe….it’s sending it to protection mode.
Resistance measured around u7000 looks within spec.
u7060 pin1 is about 4v when it should be 0.30v.
Pin4 is 0v when it should be about 18v.
So what’s going on is that chgr_amon should be low but it’s not.
Since it’s a current sense problem of the charger I measured resistance on pins 27 and 28 of u7000 and I’m getting a very high resistance when it should be about 20ohms.
Found a trace open. After fixing machine powers on.
Machine doesn’t post.
Machine missing LVDS_IG_PANEL_PWR, which comes from the MCP.
Reflowed the MCP with the RE-8500 station and the board now works fine.
Replaced the MCP and the stressed tested the board for three hours.
All passed board fixed.

Summary
Created by

ALRC

Completed on

November 11, 2014

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