How To Fix a MacBook Pro A1706 Stuck on 5V and boot looping: Difference between revisions
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== Problem description == | == 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. | |||
[[File:A1706-resistors.png|thumb|MacBook Pro - A1706 Corroded Resistor near CD3215]] | |||
== Symptoms == | == 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. | |||
Latest revision as of 22:11, 13 October 2025
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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.