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820-02020 A2338 2020 MacBook Pro problem with PP3V3_S2

S

sekidata

Member
This is the first M1 board I have worked on, so still learning the new nomenclature. Its USB-C is at 20V, drawing 0.02A. I found a short to ground on PP3V3_S2, which I traced to its power chip UC710 and open current sense resistor RD560. I replaced UC710 and RD560, which removed the short. Now I have:

PPBUS_AON: 12.0V
PP3V3_AON: 3.3V
PP1V8_AON: 1.8V
PP3V8_AON: 3.8V
PP3V3_S2: 2.8V
P3V3S2_EN: 1.8V
 
2informaticos

2informaticos

Administrator
Staff member
Looking good and checked good is not the same.
RC709-13 set the 3V3_S2 voltage.
Check what happens soldering 150K in parallel with RC713.
 
S

sekidata

Member
By "looking good" I meant I measured all resistors. You were right about checking their traces, though. I reflowed the area because of one small corrosion spot and now I get 3.5V on PP3V3_S2.

The machine is starting up now.
 
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