Xiaomi Mi 10 Does Not Display Issue Repair
Model: Xiaomi Mi 10 5G
Announced: 2020, February 13
Defect Phenomenon
The screen does not display after the phone is dropped, but there was still a sound when a call is received.
At first, the client thought that the screen was broken, then went to Xiaomi’s official after-sales service to ask for help, and replace a new screen the issue still remains the same. It should be the motherboard with the problem.
Because the replacement cost of Xiaomi’s official motherboard is too high, so send it to a repair shop to repair, but the issue cannot be fixed, then send it to us to repair.
Troubleshooting
First, let’s disassemble the phone and take out the motherboard
The issue is no display, so we focus on checking the parts relative to the display function. Checking under the microscope, find some problems
- The display connector has been reflowed by the previous repair technician
- A small component is missing, and the pad on the PCB was dug with a hole
Take a good motherboard for comparison, the missing component is a small CR6400.
It’s on the LCD_RESET_N signal, and when measuring the diode value on the good motherboard
- the pin 20# of J6400 is around 400
- the CR6400 side which is connected with J6400 is also around 400
Measure the diode value on the pin 20# of J6400 on the damaged motherboard, it’s OL!
So the issue should be the inner line between the J6400 pin20 and CR6400 is broken. We need to jump a wire to fix the issue.
Repair Process
Jump wire between pin20 of J6400 and CR6400
Measure the diode value on the dug pad of CR6400, it’s grounded. So we need to scratch out the PCB paint to find out the inner line.
- Remove the connector and small components around CR6400
2. clean the PCB pads under the J6400 with solder wick
3. Scratch out the inner rail which connected with CR6400 slightly
keep scratching a little bit…
When scratched out the inner rail then measured the diode value with the multimeter, the measured diode value is 400.
The diode value is OK!
4. Jump wire between CR6400 and pin20 of J6400
You can visit the REWA Academy handwork course to learn the detailed jump wire process.
5. After jumping the wire, measure the diode value on J6400 pin 20, it also shows 400. The jump wire is finished, then we can solder back the display connector J6400.
6. Clean the motherboard and assemble the phone to have a test. The phone can display normally, and all the other functions also work fine.
Summary
The no display issue is caused by the display RESET signal inner line being broken. Jump a wire to fix the issue!
