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| MacBook Pro A1708 Not turning on, pulling ~0.03A at 20V repair | |
|---|---|
| Device | MacBook Pro A1708 |
| Affects part(s) | Motherboard |
| Needs equipment | multimeter, soldering iron, soldering station |
| Difficulty | ◉◉◉◌ Hard |
| Type | Soldering |
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Problem description
Usually if you have a MacBook which pulls around 35 milliamps at 20V, PPBUS_G3H will be missing as well.
Symptoms
- Not turning on
- Pulling ~35 milliamps at 20V as measured by a USB-C meter
- PPBUS_G3H missing
Solution
Replaced Q7030 and U7000 (ISL9239HI with ISL9239C0) without any changes to the fault. With a partially charged battery, the logic board would offer fan spin and briefly show the battery icon to request the charger to be plugged in. The official power adapter (Type C) would not charge this new battery with 1 charge cycle (vendor supplied). The root cause was with SMB_SMC_CHGR_SDA. Voltage on SMB_SMC_CHGR_SDA was at 0.8 V while SMB_SMC_CHGR_SCL was at 3.3 V when the logic board was powered. Checked the local pull-up resistors being present for this SMBUS shared bus (R5380, R5381). Each was being pulled up to the PP3V3_G3H rail (3.42 V). All correct. The faulty component causing this stuck SMB_SMC_CHGR_SDA line was at D6950. This TVS diode must have been leaking. Upon removal off the logic board, the resistance to ground for both the SCL and SDA lines increased. Powering up, the PPBUS_G3H returned to normal and now the logic board is booting and charging the new battery. In hindsight, do not believe that U7000 nor Q7030 required to be replaced. The SEMTECH RCLAMP3552T part at D6950 is available from Arrow and other distributors.