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MacBook Air A1932 Not turning on, pulling very low current at 5V or 20V repair

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MacBook Air A1932 Not turning on, pulling very low current at 5V or 20V repair
Device MacBook Air A1932
Affects part(s) Motherboard
Needs equipment multimeter, soldering iron, soldering station, thermal camera
Difficulty ◉◉◉◌ Hard
Type Soldering


Problem description

Diagnosing and resolving issues where a MacBook (820-01521) is pulling very little current at either 5V or 20V as indicated by a USB-C current meter with SLPS2R and AWAKE voltages/signals cycling.

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Symptoms

  • MacBook not turning on
  • Very low current draw at either 5V or 20V
  • SLPS2R and AWAKE voltages/signals cycling

Solution

Diagnostic Steps

Check voltage and resistance to ground on

PP5v_G3S

The resistance to ground on PP5v_G3S should fairly high, well within the kilo-ohms. Voltage should be around 5v. Values less than 4.9v should be considered abnormal.

PP3v3_G3S

The resistance to ground on PP3v3_G3S should fairly high, well within the kilo-ohms. Voltage should be around 3.3v. Values less than 3.215 should be considered abnormal.

PP1v8_G3S

The resistance to ground on PP1v8_G3S should fairly high, well within the kilo-ohms. Voltage should be around 1.8v. Values less than 1.70v should be considered abnormal.

PP3v_G3H

The resistance to ground on PP3v_G3H should fairly high, well within the kilo-ohms. Voltage should be around 3.0v. Values less than 2.915 should be considered abnormal.

Repair Steps

If no shorts were found on the listed rails above, replace U7800.

If you found a short on the listed rails above, inject 1v into the rail and perform thermal imaging. Replace the shorted component.