Redmi K40 game enhanced version automatically restarts without booting (CPU virtual welding)

Redmi K40 game enhanced version automatically restarts without booting (CPU virtual welding)

Redmi K40 game enhanced version, automatic restart does not boot. Machines that can’t automatically restart into the system are a common problem for Redmi. Basically, they are all CPU virtual welding, so we can just remove the CPU and redo it.

“Fault model” Redmi K40 game enhanced version

【 Fault Phenomenon 】 Automatic restart without booting.

[Maintenance process] I received a machine sent by a customer for repair, the model of which is Redmi K40 game enhanced version, and the fault was suddenly restarted for normal use.

Redmi K40 game enhanced version automatically restarts and does not boot Figure 1.

This kind of machine that can’t automatically restart into the system is a common problem for Redmi. Basically, it is a virtual welding of CPU, so we can just remove the CPU and redo it.

First, look at the current on the single board, and then restart when it normally jumps to 600mA. After removing the CPU, the single board is powered on and triggers the current of 36-58-75-32-0, which is considered normal. After installing the lower CPU, the current of 300-500-600 returns to zero, which feels a little wrong. After measuring the power supply resistance of the CPU, it is normal, and after installing the cover, the current becomes 80-130-260-.

Redmi K40 game enhanced version automatically restarts and does not boot Figure 2.

We can start the machine directly by installing the button screen.

Redmi K40 game enhanced version automatically restarts and does not boot Figure 3.

[Maintenance Result] Install the motherboard into the shell.mobile phoneIt can be turned on normally, and the functions of WiFi, Bluetooth, voice, charging, fingerprint, taking photos and making phone calls are all normal, so the maintenance is over.