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| How To Fix a MacBook Pro A1706 Stuck on 5V and boot looping | |
|---|---|
| Device | MacBook Pro A1706 |
| Affects part(s) | Main Logic Board |
| Needs equipment | Soldering Iron, Hot Air Station, Flux, Microscope, Tweezers |
| Difficulty | ◉◉◉◌ Hard |
| Type | Soldering |
Problem description
A MacBook Pro A1706 (13-inch, Touch Bar) presents 5V and power cycling only on USB-C after liquid exposure near the CD3215 USB-C controller area.
On inspection, resistors near the CD3215 IC are found corroded, interrupting the communication and power negotiation process between the logic board and the charger.
Symptoms
- MacBook does not power on.
- USB-C meter shows 5V only, no negotiation to 20V.
- Visible corrosion around CD3215 IC.
- USB-C meter power cycles.
Diagnostic Steps
- Visual Inspection
- Examine both left and right CD3215 controllers near the USB-C ports.
- Look for corrosion, green residue, or burnt resistors in the LDO / CC line areas.
2. USB-C Meter Test
- Connect charger → verify if voltage negotiates to 20 V.
- If it stays at 5 V, the CD3215 cannot communicate with the SMC or is missing key pull-ups.
3. Resistance Check
- Probe resistors connected to:
- CC1 / CC2 lines
- LDO_1V1 / LDO_1V8
- SCL / SDA communication lines
- If any resistor reads OL (open) or drastically higher resistance, replace it.
4. Communication Check
- Inspect the LDO resistors (typically 1 MΩ) next to the CD3215 IC.
- If corroded, CD3215 cannot detect the charger and initiate PD handshake.
Repair Steps
- Clean the Area
- Remove conformal coating and corrosion with IPA and soft brush.
- If pads are damaged, repair traces under microscope.
2. Replace Faulty Resistors
- Identify corroded resistors (commonly R3108–R3109 or nearby on CD3215 lines).
- Replace with correct values per schematic (typically 1 MΩ depending on the line).
3. Inspect Capacitors
- Check small caps near LDO and CC lines for shorts. Replace if leaky.
4. Reflow / Replace CD3215 (if needed)
- If corrosion extends under the CD3215 IC, reflow or replace it after cleaning pads thoroughly.
5. Test USB-C Negotiation
- Reconnect charger — voltage should rise to 20 V / ~0.6 A–0.8 A, indicating successful handshake.