(SOLUTION) Xiaomi MI 9T (REDMI K20) no sound, microphone and speakers not working

☝️ How to Disassemble the Smartphone: 

For a detailed disassembly guide, check out this link: [How to Disassemble Xiaomi MI 9T]

⚠️ Before disassembling, do not forget to turn your phone off.

 

The device came in for repair with the following issue: no sound at all during calls or media playback.

After a quick diagnosis, it was determined that the headset icon was not showing up, which ruled out a software or settings issue. Instead, the problem was likely related to an unconnected headset jack.

However, there was a strange observation: during calls, the speakerphone would automatically activate.

This behavior is strikingly similar to a common issue with the iPhone 7, where broken traces under the audio codec chip cause the same symptom. 😂

1️⃣ Disassemble the Phone:  

To start, I carefully disassembled the phone. Just to be thorough, I also inspected the lower board and checked the headset jack located on the top of the main board. ☝️  

2️⃣ Inspect the Board for Liquid Damage or Physical Defects: 

I examined the board for any signs of liquid damage or mechanical issues.  

2️⃣ Inspect the Other Side of the Board:  

I flipped the board over and checked the other side for liquid damage or physical damage.  

Visually, everything looked fine, so I concluded that the issue was likely with the audio codec chip.  

3️⃣ Carefully Cut a Section of the Metal Frame:  

Using precision tools, I carefully cut out a small section of the metal frame near the location of the WCD9375 audio codec chip.  

4️⃣ Replace the Audio Codec Chip:

Using a soldering station, I removed the faulty chip and replaced it with a fully functional WCD9375 audio codec chip.

5️⃣ Reassemble and Test the Smartphone:

After reassembling the phone, I tested it thoroughly.

Success! All sounds were restored, and the device was functioning perfectly in normal mode. 👍

Key Takeaways:

- Diagnosis is Critical: Identifying the root cause (in this case, a faulty audio codec chip) is essential for an effective repair.

- Precision Matters: Careful disassembly and soldering are crucial to avoid further damage.

- Similar Symptoms Across Devices: Issues like this can occur across different smartphone models, so knowledge from one repair can often be applied to others.

This repair is a great example of how technical expertise and attention to detail can bring a seemingly "dead" device back to life! 🛠️📱