MacBook Pro A2251 20V on USB-C, 0.00-0.01A current draw repair | |
---|---|
Device | MacBook Pro A2251 |
Affects part(s) | Motherboard |
Needs equipment | multimeter, soldering iron, soldering station |
Difficulty | ◉◉◉◌ Hard |
Type | Soldering, Micro-Soldering"Micro-Soldering" is not in the list (Soldering, Teardown, Part replacement, Cleaning, Software, BGA, General) of allowed values for the "Repair Guide type" property. |
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Problem description
Dealing with a MacBook (820-01949) showing 20V on USB-C with a current draw of 0.00-0.01A.
Symptoms
- MacBook displaying 20V on USB-C ammeter
- Current draw registering 0.00-0.01A
Solution
Diagnostic Steps
Check PMU (U7800) Input
- Verify if PMU U7800 (Figure 1) is missing 12V input (PMU_VDD_HI) caused by R8050 (Figure 2) being blown or corroded.
- Check resistance on R8050; normal value should be around 877kΩ.
- Note: R8050 is part of a voltage divider circuit, so voltage will be lower on pin 2 of the resistor.
Repair Steps
Blown R8050 with Short to Ground
- If R8050 is blown and there's a short to ground on pin 2, replace both U7800 and R8050.
Blown R8050 without Short to Ground
- If R8050 is blown but no short to ground is found, replace R8050.