My Solution

Heres the solution for Nokia E73 with charger not supported problem.This kind of charging problem only shows "charger not supported" on the LCD screen display when the USB charger is being plug-in.

The solution below shows a certain components that needs to be replace if this kind of problem occurred on Nokia E73. There is thermal resistor which has a resistance value of 47K. If these resistor become faulty or already damaged it will result to charger not supported problem on the device.
The 47K BTEMP (battery temperature) resistor is located or mounted near the keypad pin connector just the bottom of the Nokia E73 PCB board. You must replace it with same value or type or it will not fix the problem.