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| MacBook Pro A1708 Not turning on, PPBUS G3H shorted to ground repair | |
|---|---|
| Device | MacBook Pro A1708 |
| Affects part(s) | Motherboard |
| Needs equipment | multimeter, soldering iron, soldering station, thermal camera |
| Difficulty | ◉◉◉◌ Hard |
| Type | Soldering |
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Problem description
#incomplete
Symptoms
- sub 20 ohms on PPBUS_G3H
- Not turning on
Solution
Inject 1 V (increase if no reaction), watch for hot spots with thermal cam. Usually it's a bad tantalum cap on the PPBUS_G3H rail.
Example video (Taking 20 V, 0 A. Ethanol used instead of thermal cam with 0.8 V on PPBUS_G3H, resistance between PPBUS_G3H and CPU coil is 3.6 Ω) Example 2: https://www.youtube.com/watch?v=TZsvvUWUInE (Taking 20 V, 20 mA. Bad capacitor located via visual inspection)
Read the resistance from PPBUS_G3H to Vcore coils (coils around CPU/GPU) IF those measure UNDER 1 Ω (0.3–0.8) then you most likely have a direct 12 V short to CPU/GPU. On this board this situation is always a no fix.