MacBook Pro A2338 Not turning on, 0.20-0.25a current draw at 5V with power cycling of the USB-C amp meter repair: Difference between revisions
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Latest revision as of 15:19, 29 October 2023
| MacBook Pro A2338 Not turning on, 0.20-0.25a current draw at 5V with power cycling of the USB-C amp meter repair | |
|---|---|
| Device | MacBook Pro A2338 |
| Affects part(s) | Motherboard |
| Needs equipment | multimeter, soldering iron, soldering station |
| Difficulty | ◉◉◉◌ Hard |
| Type | Soldering |
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Problem description
No Power on, 5v and ~0.20-0.25a as measured on the USB-C amp meter, with power cycling of the USB-C amp meter on the 820-02016 logic board.
Symptoms
- 5v / ~0.20-0.25a with power cycling of the USB-C amp meter.
- All voltages missing
Solution
Diagnostic Steps
High-resolution thermal imaging is the preferred first-line diagnostic method on M1-based boards when a short to ground on an S2 rail is suspected. Voltage injection is usually not required. If high-resolution thermal imaging is unavailable, proceed to the steps below to identify a short on PP3v3_S2 or PP1v25_S2.
Measure diode mode readings to ground on PP3v3_S2
- LC710 is the best place to measure for a short on PP3v3_S2 on the 820-02020 logic board.
- Place your multimeter in diode mode, and place the red probe on a grounding point such as a screw hole and the black probe on LC710.
- Normal diode mode reading to ground on PP3v3_S2 is around .440.
Measure diode mode readings to ground on PP1v25_S2
- Pin 2 of L77D0 is a good place to measure from.
- Normal diode mode reading to ground on PP1v25_S2 is ~0.490.
Shorts to ground are generally considered when the diode mode to ground reading is significantly less than the above normal values. Readings can vary due to temperature or normal wear.
How to find short circuits If a short to ground is measured, inject voltage to the associated line. Generally, 1v at 3-5 amps is sufficient to find most short circuits. NEVER INJECT MORE VOLTAGE THAN THE LINE IS RATED FOR! Carefully feel around the board for a warm area or utilize thermal imaging, then localize the shorted component using isopropyl alcohol. The alcohol will rapidly evaporate off the shorted component.
Repair Steps
Short to ground on PP1v25_S2 or PP3v3_S2
- Replace the shorted component.