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| How To Repair iPhone 12 Pro Max No Audio | |
|---|---|
| Device | iPhone 12 Pro Max |
| Affects part(s) | Main Logic Board |
| Needs equipment | Hot Air Station, Soldering Iron, Solder Paste, Reballing Stencil |
| Difficulty | ◉◉◉◉ Specialist |
| Type | Soldering |
Problem description
An iPhone 12 Pro Max presents with no sound from the bottom loudspeaker and no vibration feedback.
Standard checks such as speaker replacement and amplifier IC replacement fail to resolve the issue.
Root cause: a faulty Sakkonet IC, resulting in loss of both audio output at the bottom speaker and haptic feedback.
Symptoms
- No sound from the bottom loudspeaker (earpiece works normally).
- Vibration motor not working — no haptic feedback or alerts.
- Speaker and taptic engine test fail in diagnostics.
- Audio ICs and lines appear normal under diode mode check.
- Replacing both audio amplifier ICs does not fix the issue.
- Issue resolves completely after replacing the Sakkonet (U8400) IC.
Solution
Diagnostic Steps
1. Visual Inspection
- Examine the logic board, especially around the audio amplifiers and Sakonnet IC area, for corrosion, liquid exposure, or burnt components.
- Inspect speaker and Taptic connectors for broken pins, lifted pads, or corrosion.
- Verify that the bottom loudspeaker and Taptic Engine are OEM units and not aftermarket replacements.
2. Replacement Test (Peripheral Check)
- Temporarily connect a known-good bottom speaker and Taptic Engine to rule out external faults.
- Power on the device and test for sound output and vibration feedback.
- If both remain dead, proceed with IC-level diagnosis.
3. Audio Amplifier Replacement
- Replace both audio amplifier ICs.
- Retest the device after each replacement.
- If there’s no improvement, the fault likely lies in the Sakonnet (U8400) IC rather than the amps themselves.
4. Sakonnet IC Replacement
- Replace the Sakonnet IC (U8400) using controlled temperature.
- Clean the area, reball the IC, and ensure all power rails are intact.
- After replacement, reassemble and retest:
- Bottom speaker should now output audio.
- Taptic feedback should return to normal.
5. Confirmation
- Verify all audio functions:
- Bottom loudspeaker output
- Haptics/vibration
- Confirm normal current draw and no abnormal heating near Sakonnet.
Repair Steps
1. Preparation
- Disconnect the battery and remove the logic board from the housing.
2. Audio Amplifier Replacement (Preliminary Step)
- If corrosion or reflow signs are present, replace both audio amplifiers.
- Reball and reflow the Speaker amps.
- After installation, reassemble partially and test with known-good speaker and Taptic Engine.
- If both remain dead — proceed to Sakonnet replacement.
3. Sakonnet IC Removal
- Using flux, heat Sakonnet IC area.
- Gently lift the Sakonnet IC (U8400) once solder is molten.
- Clean pads on the board thoroughly with solder wick and flux.
4. Reball & Reinstallation
- Reball the donor Sakonnet IC with fresh solder balls.
- Align precisely to the board pad array under microscope.
- Reflow and Install IC.
- Allow to cool and clean the area.
5. Post-Repair Testing
- Reassemble logic board, connect battery, speaker, and Taptic Engine.
- Power on and test:
- Bottom speaker output — play music or ring test.
- Vibration feedback — toggle silent switch or test via settings.