Poco X3 Pro Not Charging

Poco X3 Pro Not Charging
Device	Poco X3 Pro
Affects part(s)	Logic Board
Needs equipment	Soldering Iron, Hot Air Station, Microscope
Difficulty	◉◉◉◉ Specialist
Type	Soldering

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Problem description

If you have a phone in this condition it will have a issue with no charging/ slow charging. If you have tried new charging port or whole dock assembly then proceed to the following steps.

Symptoms

• No charging symbol when charger is plugged in
• Charging symbol shows up while plugging but the phone charges very slow or does't charge at all.

note: If you have a phone with slow charging or with no fast charging then try to replace the battery with known good OEM one.

Diagnostic Steps

The problem of the charging is a little complicated but if you follow the steps below exacly I show then you will be able to solve the issue of the phone.

• Check if VBUS reaches to the main board from the bottom board(as shown in the picture). If you don'e see 5 volts in this specific line then you should proceed to run a jumper from bottom board 5V VBUS and jumper to this point and check.

VBUS

• Check if OVP IC(over voltage protection circuit) is working properly or not:
  • Check the cap OVP_IN if 5 volt are available there, if they are not available then you probably have a missing line from VBUS to OVP_IN, run a jumper wire and the issue will be solved.
  • Check the cap OVP_OUT for 5v, if not available then you can run a jumper from OVP_IN to OVP_OUT and check. (if the OVP IC is burned it is recommended to remove it or replace it if you have one)

OVP IC

• Check the charging ic:
  • Check if the charging ic is outputing voltage in the line called VPH_OUT (without battery)
    • if vph isn't being outputed then the problem could be the charging ic itself or it could have a minor short on the VPH_OUT
    • Check for shorts near the charging ic

CHARGING IC + BOOTCAP

• Check bootcap: (The bootcap is a capacitor required for charging, if it shorted or missing the phone will go in fake charging condition)
  • Check for shorts on both sides of the bootcap
  • It is a cap that is not connected to Ground so to properly check if its shorted or not is to just place both the multimeter probes on the 2 poles of the capacitor to check it
  • this capacitor should output 7-9volts on the one side and 3-4 volts on the VPH side. If it outputting the same voltage on both sides then you probably have a faulty charging ic, proceed by replacing it.