As we all know, now we can fix iPhone Face ID not working issue by replacing dot matrix flex cable or IC, but some users feedback that the iPhone Face ID is still not working after repairing, what's up? Here are some reasons and solutions.
Before we are going to talk about these problems, we need to know the functions of the dot projector pin. Here are 2 pictures.
X-wire pad
Here are some problems/reasons/solutions after repair:
1. After repairing, it prompts "Face ID cannot be activated on this iPhone.
- Data writing is abnormal. If the data is written incorrectly or fails, please write it again. If the dot projector code can be read by the JC Repair Assistant App, it indicates that the data is written normally.
- If other components of the dot projector are working abnormally, such as Flood illuminator, ambient light sensor, and infrared camera, they can also be detected on the JC Repair Assistant and display "000000" or " abnormal", indicating a problem.
- Use DT-20N digital multimeter to check that whether the ground resistance of the dot matrix inline base on the motherboard is normal.
2. Virtual flicker of protait
- Not all four sets of lights are on.
- Lattice and Prism are not aligned.
- Infrared, dot matrix alignment deviation needs to be adjusted.
3. Face ID can be recorded， but not unlocked
- In settings, only the password function can be turned on, but the face ID unlock function is not turned on.
- The luminescent body can't be replaced, otherwise it will cause that the recorded face can't be unlocked.
4. Unstable unlocking
- The version of the IOS system should be hiher than IOS 13. Lower version will result in incomplete compatibility.
- Infrared, dot matrix alignment deviations need to be adjusted, or the front module is biased after assembly to the screen.
5. Other issues
- After a period of use, the glue is not secure and the prism has shifted.
- Residual glue in the prism affects Face ID recording and should be cleaned up.
- The prism is visibly damaged both inside and outside, so the prism can be replaced and the model is as identical as possible.
- Carefully check whether there are cracks in the magnetic ring of the light-emitting components, this can result in unable to unlock or unable to repair.
- Keep the original glue between the prism and the magnetic ring as far as possible.
- When bonding the prism to the front ring, the glue should not be too much and then sticking to the illuminator or prism can cause instability in unlocking
- When the MOS tube is shorted, the three solder joints on the prism do not need to be welded.
- If the frame of the front camera is severely deformed can cannot be adjusted properly, the front frame can be replaced.
Finally, here are some tips for testing result by dot projector programmer.
- NTC(temperature control): disconnection
Most of them are the disconnection of the gold wire at both ends of the temparature control detection resistance, or the poor welding between the light-emitting componenets and the flat wires.
- Test result: Fused
Filed effect transistor(MOS transistor) works normally, short circuit please.
- Test result: I2C/IIC communication abnormal
The data cable is disconnected and the encrypted data can't be read, the flex cable is damaged, the enctryption chip is damaged, or the light-emitting componenets and the flex wire are not welded well.
Test result: abnormal luminescence
The solder joint of the light-emitting module is not cleaned up, or the tin on the wire is not uniform, which leads to the poor welding between the light-emitting module and the wire.
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