Hello Every One ,

This is the Redmi Note 9 Pro Max mobile. The customer brought this mobile to our shop. The technician asked the customer what is  problem in this mobile .Customer said mobile went into dead condition.The technician said he will check the mobile and repair it.

Now let's check this mobile :

• If the mobile is connected to the 6 in 1 charger, it takes 0.1 milli ampere .
• This mobile has already gone to another shop. We have to observe the mother board carefully.
• If observed, work has been done in the lighting section near the secondary PM ic .
• The rectifier diod is the pad that has come off. Another technician has put the jumper from there.
• Connect the charger near the main pm ic and check whether vph power is coming or not.
• Check if the vph power return is coming to the IC.

Krish Mobile Training Institute

• Check whether the voltage is coming on the buck coils.
• Check whether 2V is coming above the higher LDO.
• Secondary PM should be checked whether the input vph power 3.4V is coming or not.
• Check whether the voltage is coming across the buck coils around the secondary PM IC.
• Lower LDO 1.3v Check whether is coming or not.
• Check whether 2.2 V is coming on the bob coils.

If you want to Know More Information then Click on this Link :-www.youtube.com/@krishmobiletraininginstitute.

Now let's solve the problem in mobile :

• All buckcoils have output on coils.
• there is no problem near the main PM and secondary PM.
• But the mobile is not turning on.
• Now check v reg bob line is generated or not.
• Check if this reg bob voltage comes with 3.0 and 3.6V voltage.
• v Reg Bob Voltage also arrived.
• When we checked the secondary PM, all the voltages came.
• But the secondary PM ic heats up.
• If the secondary PM is checked by adding rosin smoke on top, it will melt.
• There is a problem in the secondary PM ic.
• If you check the voltages after the secondary PM melts, you will not see any voltages.

• So secondary PM has a shot now.
• Now we have to remove and change the secondary PM.
• The ground should be cleaned with a wick.
• A new secondary PM has been refixed.
• After changing the new ic, add rosin smoke again and check whether the ic melts.
• The voltages are all coming up.
• We have attached the mother board to your mobile and checked whether the mobile turns on or not.
• Mobile will turn on if checked.
• But the problem is that the mobile display is cracked.
• The customer did not ask us to change the display.
• problem solved .
• customer is happy .

video link is given in the below :

Thank you by team k.m.t.