MacBook Pro 16" 2021 M1 Max: Thunderbolt Charging Failure
Overview
A music producer from North Rocks brought in their high-spec MacBook Pro 16-inch M1 Max that suddenly stopped charging through any USB-C port. MagSafe charging still worked but was slow. One Thunderbolt port had been damaged by a faulty third-party dock. Apple quoted $1,199 for logic board replacement. Component-level diagnosis identified the damaged controller, allowing targeted repair.
Initial Symptoms
- No charging via any of three USB-C/Thunderbolt ports
- MagSafe charging worked but limited to 67W (not 140W)
- Thunderbolt devices not recognised
- USB devices worked on one port only, limited speeds
- Problem started after using third-party dock that "sparked"
- System Information showed Thunderbolt bus missing
Diagnostic Process
M1 Max Power Architecture
The MacBook Pro 16-inch M1 Max has sophisticated power delivery:
- MagSafe 3: Up to 140W fast charging
- USB-C/Thunderbolt: Up to 100W Power Delivery
- Internal distribution: Power managed by M1 Max SoC and supporting PMICs
Port Testing
Using USB-C diagnostic tools:
- Port 1 (damaged): No CC line activity, 0V on all power pins
- Ports 2-3: CC lines present but no PD negotiation occurring
- MagSafe: Functional but limited negotiation
Component Analysis
The third-party dock caused a surge that damaged the TPS65994 USB-C Power Delivery controller. This chip manages all USB-C port power negotiation. When it fails, USB-C charging stops working even though the ports may still pass data at reduced speeds.
Related Damage
We also found damage to protective components around Port 1—ESD diodes and filter capacitors sacrificed themselves protecting the logic board from worse damage.
Repair Process
Damaged Component Removal
- Removed failed TPS65994 controller using hot air at 360°C
- Removed damaged ESD protection diodes around Port 1
- Cleaned affected area and inspected traces
Component Replacement
- Installed replacement TPS65994 from donor board
- Replaced ESD protection components with new parts
- Verified all solder joints under microscope
Testing
- USB-C charging restored on all three ports
- 100W Power Delivery negotiation working
- MagSafe now negotiating full 140W
- Thunderbolt bus detected, full 40Gbps confirmed
- All ports tested with multiple devices
Outcome
The music producer's £3,000+ MacBook Pro was saved from expensive board replacement. All charging and Thunderbolt functionality was restored. We recommended using only quality, certified docks going forward.
Key Takeaways
- Third-party accessories can cause damage: Poor-quality USB-C docks and chargers can damage charging circuits.
- Component-level repair saves expensive machines: A $1,199 board replacement avoided with targeted chip repair.
- Multiple port failures often share a cause: When all ports fail together, a shared controller is likely.
- Surge protection helps but has limits: ESD components protected the main board but were sacrificed.
MacBook Charging or Port Issues?
If your MacBook has USB-C or charging problems, component-level diagnosis can identify fixable faults.