Hello
im having a 10000mAh power bank with controlling board Qualcomm QC 3.0
The power bank is new and it only got charged/discharged like almost 5~7 times.
The battery is JBL LiPo 10Ah and it can be charged-discharged 500 times.
The powerbank was working nice until it fall down once and stopped charging and after opening and checking the board found out that the 4R7 inductor was broken i changed it and i found shortening in the output cable and i fixed it but still it gives 3.9v output.
The batteries getting charged normally but the output of power bank still 3.9v not 5v.
Any possible theory for what could be damaged and how to fix it?

 

Welcome to AAC!
In the fifth picture, two black components at the top of the picture show signs of heat damage.
The 4R7 resistor below them also looks to have overheated and melted its solder joints.
I reckon that the inverter which normally generates 5V from the cell's 3.9V is now fried.

 

The 4R7 resistor below them also looks to have overheated and melted its solder joints.

The 4R7 is the inductor which TS replaced.

I reckon that the inverter which normally generates 5V from the cell's 3.9V is now fried.

I agree.

 

What is the replacement inductor (4R7) current rating? It must be over 2-3 A.

 

Welcome to AAC!
In the fifth picture, two black components at the top of the picture show signs of heat damage.
The 4R7 resistor below them also looks to have overheated and melted its solder joints.
I reckon that the inverter which normally generates 5V from the cell's 3.9V is now fried.

Hi alec
Thank you for responding
First the 2 black components are just a plastic cover and the 4R7 is new i just soldered it but the soldering is not that clean .
About the inverter which one of them is that i mean which components are responsible for it that i need to change

 

What is the replacement inductor (4R7) current rating? It must be over 2-3 A.

Yes it is same as the original one.

 

About the inverter which one of them is that i mean which components are responsible for it that i need to change

I don't know, as there's no schematic.

 

Is the boost converter built from discrete components? I don't see any converter chip on posted pictures.