5800 Xpressmusic LCD Screen Display Problem Repair Procedure

**..:sunil:..** · 23-06-2010, 12:38 PM

Step by step repair procedure on Nokia 5800 Xpressmusic mobile phone LCD screen display problem.
This mobile phone repair tutorial, only applicable if after replacing a good LCD replacement or rest assured that the LCD screen is working fine but the display problem still exists.

The repair guide picture below is the location of the 5000 xpressmusic's LCD connector and a an EMI filter IC near to it.
If the LCD connector is seemingly okay and the quickest method is to replace the EMI Filter IC which has a product code value of EMIF07-LCD02F3 . In this IC where the four data signals feeds across from the Application processor through the LCD screen circuit.

But after replacing it and nothing happens and the problem remains, here's a simple hints for beginners on LCD repair procedures, this one can be applied in any mobile phone repairs, and this one can save time, rather than rushing through.
Analyze the circuit and understand how the LCD circuit works and use schematic diagram to be familiar with its components locations.

This next repair guide picture that i prepared below is the tracing and test spots on 5800 xpressmusic LCD connector and components, a good way to start on checking up and test on that spots there.

Those two line coils connected to pin 10 and pin 12 are the LCD's supply voltage. You may check it first if it has a continuity, if found open, replace it. The four test spots on the PCB board is connected from the EMI filter bumps or terminal through to each corresponding LCD connector pin numbers, trace and check it also. If found open, you may apply a tiny jumper unto it.

Voltage line checking is also a powerful technique of advance hardware troubleshooter on cell phone repair.
You may apply voltage to the handset and power it up and measure the voltage line paths as shown on the example repair guide picture below.

LCD screen display used two types of different amount of voltage from the power management IC, to make it work. One is called "VAUX" that is approximately 2.8volts DC and the other one is "Vio" that is about 1.8 volts DC.
If all the above repair procedure is have been done and seemingly not solve the problem, you may replace the EMI filter or you may use this repair guide picture below.

The EMI filter bumps configuration is shown right, the bumps that are connected is where the LCD data signal flows, the remaining bumps are all connected to PCB ground lines.