MacBook Pro 15 Inch Touch Bar 2018 USB C Controller Repair

Introduction

Use this guide to diagnose and repair a MacBook Pro 15-inch Touch Bar 2018 model A1989 that won't charge because USB-C Power Delivery negotiation is stuck at 5 V. The USB-C port controller tells the charger to raise the voltage to about 19–20 V. Oxidation around the port, FPC connector, PP3V3_G3H power rail, or controller can stop that negotiation and prevent charging. This is a microsoldering repair written for technicians. Board layouts on related MacBook models may have minor differences, so verify all chip names and rails with the correct schematic and boardview.

What you need

Step 1 Prepare the MacBook

Shut down the MacBook, unplug every cable, and remove the lower case using a MacBook-compatible screwdriver set.
Disconnect the battery before measuring, cleaning, or heating the logic board.
Work on an ESD-safe mat and wear safety glasses while soldering or using hot air.
Use fume extraction when heating flux, solder, or oxidized residue.
Remove the logic board only if you can keep track of every connector, bracket, and screw location.

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Step 2 Confirm the charging symptom

Connect a known-good USB-C charger and USB-C power meter to one USB-C port.
Watch the voltage when the charger is connected.
A normal port briefly starts at 5 V, negotiates USB Power Delivery, and rises to about 19–20 V.
A faulty port stays at 5 V and doesn't request the higher charging voltage.
A bench power supply set to 20 V with a USB-C test lead can be used instead of a charger-based tester.

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Step 3 Compare every USB C port

Test each USB-C port and record which ports rise to about 19–20 V.
Use a working port or side as a reference for the failed side.
Some MacBook boards lose all USB-C ports when one port or controller fails.
Some failures affect only one side of the MacBook, such as both left-side ports staying at 5 V while the right-side ports work.

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Step 4 Inspect the USB C area

Place the logic board under a microscope and inspect the USB-C port area.
Follow the USB-C port connection from the port FPC under the plate to the nearby USB-C port controllers.
Look for a red liquid contact indicator, white or green corrosion, missing pads, and burned components.
A red liquid contact indicator confirms liquid exposure, but it doesn't prove which controller has failed.

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Step 5 Clean oxidized areas

Apply isopropyl alcohol to the oxidized area and scrub gently with an ESD-safe brush.
Clean around the USB-C port FPC, the nearby small components, and the USB-C controller.
Dry the board completely before applying power or heat.
Inspect the cleaned area under the microscope for carbonized parts and corrosion trapped beside the chips.

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Step 6 Check the controller power rail

Locate the USB-C Port Controller in the schematic, such as U31-00 or U3100.
Find the controller VDD input labeled VIN_3V3, which is supplied by PP3V3_G3H_RTC.
Use a multimeter to check that the controller has about 3.3 V on VIN_3V3.
Measure the rail at a nearby resistor or other exposed point connected to the same net.
If PP3V3_G3H is shorted, find and repair the short before reworking the controller.
A burned component on PP3V3_G3H can stop the controller from being powered.

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Step 7 Understand the negotiation path

Use this signal path as a map: charger → USB-C port FPC → USB-C port controller → PP20V_USB-C after negotiation.
Don't expect PP20V_USB-C to be 20 V before the controller completes charger negotiation.
The controller communicates with the charger and the rest of the MacBook to request about 20 V.
If VIN_3V3 is present but the affected port stays at 5 V, suspect the USB-C controller or its solder joints.

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Step 8 Identify the faulty controller

Match each failed USB-C port to its nearby controller using the schematic and boardview.
Treat a heavily oxidized controller near a port stuck at 5 V as the primary suspect.
Work on one suspect controller at a time so the test results stay clear.
Don't rework a controller that looks clean and already negotiates to about 19–20 V.

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Step 9 Try an in place reflow

Apply a large amount of thick sticky flux around all sides of the suspect controller.
Use hot air to heat the controller until the solder balls underneath begin to melt.
MacBook logic boards need longer heating than iPhone boards, but overheating can burn nearby components.
Gently move the controller with tweezers for about 5–10 seconds while the solder is molten.
Let surface tension pull the controller back into place while flux flows underneath it.
Don't keep moving the controller after the solder cools.
Thin flux can evaporate too quickly and may not stay under the chip long enough to help.

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Step 10 Retest after reflow

Let the board cool, clean the flux residue with isopropyl alcohol, and dry the area.
Reconnect only what is needed for a charging test, including the USB-C port assembly and battery connection.
Plug in the USB-C power meter and check whether the affected ports now rise from 5 V to about 19–20 V.
If the behavior changes on one controller but not another, rework the remaining oxidized controller on that failed side.
If every affected port now negotiates correctly, skip the full reball and clean the board for reassembly.

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Step 11 Remove the controller for reballing

Secure the logic board in a board holder and protect nearby plastic connectors with Kapton tape.
Apply sticky flux around the controller.
Heat the controller with hot air until the solder balls are fully molten.
Lift the controller straight up with tweezers without prying against the board.
Stop if pads lift, traces move, or the controller won't release with normal hot air rework.

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Step 12 Clean the pads

Use a soldering iron and solder wick to remove old solder from the logic board pads.
Clean the board pads and the underside of the controller with isopropyl alcohol.
Inspect the pads under the microscope for corrosion, missing pads, and solder bridges.
Don't reinstall a controller with damaged underside pads or trapped corrosion.

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Step 13 Reball the controller

Place the controller into the matching reballing stencil in the correct orientation.
Apply solder balls to the stencil openings over the controller pads.
Heat the stencil evenly until the solder balls form clean, round joints on the controller.
Let the controller cool before removing it from the stencil.
Inspect the new balls under the microscope and correct any missing, bridged, or uneven balls.

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Step 14 Install the reballed controller

Apply fresh sticky flux to the board pads.
Align the reballed controller to the board markings and pad layout.
Heat the controller with hot air until it settles into place on the pads.
Let the chip cool without touching it.
Clean the flux and inspect all visible edges for bridges, shifted alignment, or nearby disturbed components.

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Step 15 Reassemble the MacBook

Clean any remaining flux from the logic board and dry the board completely.
Reinstall the logic board in the chassis and reconnect the USB-C port FPC connectors.
Reconnect all brackets, flex cables, and screws that were removed during board removal.
Reconnect the battery after the board and connectors are installed.
Install the lower case after the first successful charging test.

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Step 16 Troubleshoot the repair

Test every USB-C port with the USB-C power meter and confirm that each port rises from 5 V to about 19–20 V.
If a port still stays at 5 V, recheck VIN_3V3, PP3V3_G3H_RTC, the port FPC, and the controller solder joints.
If PP3V3_G3H is missing or shorted, inspect the carbonized or oxidized components on that rail before reworking more controllers.
If all ports fail, isolate each port and controller because one failed USB-C section can affect the whole charging system.
If the MacBook negotiates about 19–20 V but still doesn't start, continue with a separate no-power diagnosis.

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Conclusion

Clean the board thoroughly after microsoldering and confirm stable USB-C negotiation on every port before returning the MacBook to service. Repair didn't go as planned? Try some basic troubleshooting, or ask our Answers community for help.

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