Saturday, March 12, 2011

Nokia 1616 Keypad and LCD screen display backlight problem solution

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Nokia 1616 LCD screen display and keypads LED back light problem solution
 Here's the step by step hints on how to fix the Nokia 1616 LCD screen and keypad LED problem:
This may only works assuming that you already tried the software or firmware calibration but nothing happens.  So here's the hardware repair as follows:
1. Check the VBAT 3.7V supply voltage across the two inductor coils. Check also this coils if damaged, then replace.
2. Check the the Keypad backlight LED bulb below the the circuit. If that white LED bulb is damaged the LCD backlight will also not light up or glow. So ensure that its perfectly working or replace with a new one.
3. Trace the connection line paths of the LED+ and LED- to the spots were it is being connected. There is a test spots given on the PCB board where you can check the supply voltage of the LCD backlight LED.
4. Check the switching transistor, there are two 2.2 ohms resistors which is connected to ground, replace if found damaged or faulty.
5. If all of the above procedures has been done and seems there is no problem,. You may then replace the LCD if the LCD shows a dark screen. there is a tendency that the LCD's LED is already damaged. 
You can also trace the backlight LED connection from the test spots down to the PINS or solder pads of the LCD screen, just to ensure that this connection is not open or cut-off.

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