A Surface Pro that stopped charging after a cockpit installation
The Surface Pro 10 arrived with a specific complaint: after a DIY cockpit tablet mount installation in a Cessna 172, the USB-C port would no longer charge the device. The owner, a private pilot, had wired a custom dock to the aircraft’s 28V DC electrical bus using a bench power supply cable he’d repurposed from his workshop. The Surface Pro had been powered on and functioning normally during a flight, then suddenly stopped responding to the dock. Back on the ground, no standard USB-C charger would charge the device either — not even the original Microsoft 65W charger. The tablet still worked on battery; only the USB-C port was dead.
Bench intake: fault mapping before disassembly
USB-C port assessment
We plugged in a USB-PD tester — a small inline device that shows what voltage and current a charger is attempting to negotiate on the VBUS pin. With the original Microsoft 65W charger connected to the Surface Pro, the tester showed 0V VBUS and no PD handshake. The charger was supplying power normally; the Surface Pro was not requesting it. A second USB-C data test confirmed that no USB device was detected on the port either. The physical connector pins showed no mechanical damage under magnification.
The fault was in the USB-C PD controller (the power negotiation chip, not the mechanical port) — confirmed by the complete absence of the initial 5V VBUS default state that any functioning USB-C port should assert. We also checked the Surface Connect magnetic charging port: it charged normally, confirming battery, power management IC, and the rest of the board were intact. The damage was isolated to the USB-C controller block.
The 28V DC backstory
When we asked about recent events, the owner mentioned the cockpit installation. He had wired the dock’s barrel jack to the aircraft bus through a standard automotive blade fuse — but had not confirmed the polarity of his cable relative to the dock’s pinout. Aircraft 28V DC systems use centre-positive for most accessories, but the bench supply cable he’d repurposed was wired centre-negative (a common convention on lab supplies). The dock had therefore delivered 28V DC reverse-polarity to the USB-C port’s VBUS pin. The CD3217B PD controller experienced both overvoltage (28V vs 20V max) and reverse polarity simultaneously — a double fault that destroys the internal charge pump instantaneously.
The repair
Disassembly
Surface Pro 10 disassembly requires careful application of a heat gun at 80°C to soften the display adhesive, followed by thin plastic picks to separate the display from the chassis without cracking the glass. The logic board is accessible after removing 14 screws and disconnecting 6 internal cables. We removed the board, cleaned the USB-C port area, and identified the CD3217B controller — a 20-ball BGA package approximately 3 mm × 3 mm in the top left of the logic board near the left USB-C port cluster.
BGA controller replacement
The damaged controller was removed using the rework station at 230°C peak with a 90-second ramp profile and a 60-second controlled cool. A replacement CD3217B was positioned under 40× magnification and reflowed in place. Post-reflow, the board was cleaned with flux remover and inspected under UV light for solder bridges. Reassembly and USB-PD test: the port correctly negotiated 5V, 9V, 15V, and 20V on the bench tester. Boot test confirmed Thunderbolt connectivity and charging both functional.
Invoice
Bench diagnosis and fault mapping: ₹2,000. CD3217B BGA rework (removal + replacement + clean): ₹7,500. Disassembly and reassembly (Surface Pro adhesive construction): ₹2,000. Total: ₹11,500. The owner was advised to purchase an aviation-certified USB-C power converter for the Cessna before re-installing the dock. For related Microsoft Surface repair and power jack repair cases, see our service pages.