More actions
| 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 |
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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.