MacBook Pro 14" no-power: full rail diagnosis
A repeatable order of operations for a board that draws no current, from USB-C input to SMC handshake.
Safety first — High risk
Stored capacitor energy, mains-adjacent circuits or hot air work. Discharge, insulate and work with eye protection.
Tools required
- · USB-C power meter
- · Bench PSU
- · Multimeter
- · Hot air station
- · Thermal camera
- · Boardview software
Parts required
- · Load switch IC
- · Input protection FET
- · Flux and low-temp solder
Diagnostic notes
Log the current draw at 20 V before anything else. 0.00 A means the input stage never enables; a hard short means a failed load switch or a shorted decoupling capacitor on PPBUS.
Problem mapped: Laptop shows no power · component-level severity high
Repair steps
- 1
Measure at the port
Attach a USB-C meter and record voltage and current negotiated by the charger.
Step photo placeholderMeasure at the port — illustrative repair step photo placeholder - 2
Check input protection
Diode-mode the input FETs and verify the 20 V rail arrives at the board.
Step photo placeholderCheck input protection — illustrative repair step photo placeholder Warning: Mains-side chargers and stored capacitor energy can injure. Unplug and let the board settle.
- 3
Test PPBUS for shorts
Diode-mode PPBUS to ground. Values under 0.05 indicate a hard short to hunt down.
Step photo placeholderTest PPBUS for shorts — illustrative repair step photo placeholder - 4
Localise the short
Feed the rail from a current-limited supply and use freeze spray or a thermal camera to find the hot component.
Step photo placeholderLocalise the short — illustrative repair step photo placeholder - 5
Remove and verify
Lift the suspect part, re-measure the rail, then confirm no collateral damage to neighbours.
Step photo placeholderRemove and verify — illustrative repair step photo placeholder Tip: Photograph the area at high magnification before removal so reassembly orientation is never a guess.
- 6
Replace and confirm boot
Fit a matched replacement, restore the rail, then confirm the SMC handshake and a full boot to desktop.
Step photo placeholderReplace and confirm boot — illustrative repair step photo placeholder
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