Hello Every One ,

This is Vivo Y21 mobile. The customer brought this mobile to our shop. The technician asked the customer what the problem was.He said that it says no service in this mobile.The technician said that he will check the mobile and solve the problem.

Now   let's    check   this   mobile:

• First check if there is an imei in the mobile.
• imei is not available in mobile.
• Check if the baseband version is available or not.
• unknown baseband is came in mobile .
• We have found out the problem.
• This is problem if imei and baseband version is not available in this mobile.

Now   let   us   solve    this   problem :

Krish Mobile Training Institute

• Open the mobile back panel.
• Open Borneo and go to hardware and check the voltages near 2G IC and 4G IC.
• Vio 18 pmu, vref 18 pmu, Vreg 12 pmu voltages are coming or not should be checked near Baseband IC.
• This process can be checked by inserting a sim. You can check without SIM.
• Vio 18 pmu voltage comes near baseband ic.
• Vref 18 pmu , Vreg 12 pmu These two voltages are coming once.
• vref 18 pmu, vreg 12 pmu gr value should be checked.Gr value is good.

• Now we have to check the voltages near the drx ic.
• 1.8 V but not 2.8 V should come near the drx ic.
• 2.8 V is available near the drx ic.
• Over all the voltages are all good.
• What is the solution for this, if the Baseband Ic is reballed, it will be correct. But let us replace another baseband ic.

Now let us replace the baseband ic :

• The glue around the base band ic should be cut neatly.
• Flex paste should be applied on the base band ic.
• Apply flex paste and heat slowly with a quick 857 dw+ blower.
• Lift slowly with the lifting blade while heating slowly.
• Then you have to down grade the Baseband ic pad.

If you want to See More Videos then Click on This Link :-www.youtube.com/@krishmobiletraininginstitute.

• Heat the Base band ic pad with blower and remove as much led as possible from the top of the pad.
• next clean with wick.
• Heat the baseband ic pad with blower blade and and remove as much black paste as possible from the top of the pad.
• again clean with wick.

Krish Mobile Training Institute

• Remove the baseband IC from another scrap board and fix it on the Vivo Y21 board.
• It should be properly cleaned and reballed .
• Look at the Direction and put it on the pad. Then heat it with a blower.
• Now move and set the same for it.ic fix is ​​done.
• Fix the board to the mobile and check whether the problem is solved or not.
• Imei 1 and imei 2 both came out successfully. And baseband version also came out.
• problem is solved .
• customer is happy.

VIDEO LINK IS GIVEN IN THE BELOW :

Thank you by team k.m.t.