User Guide

Display module troubleshooting
General instructions for display troubleshooting
The first step is to verify that upper and lower block cables and display module connection are working. After
that troubleshooting can go deeper. The display modules cannot be repaired.
The next step is to check that baseband engine and other display related circuits are working normally. This
can be done by connecting the phone to a docking station and starting Phoenix service software. By running
different selftests, component functionality can be checked. Follow the troubleshooting diagrams.
Operating modes of the main display
Display is in a normal mode when the phone is in active use.
Display is in a partial idle mode when the phone is in the screen saver mode.
Table 10 Display module troubleshooting cases
Display is very dim but image is seen correctly in
display.
Backlight LED components are inside the display
module. Backlight failure can also be in the
connector or in the backlight power source in the
main engine of the phone.
Image on the display is not correct or no image at
all while backlight seems to work.
Image on the display can be corrupted or part of the
image can be missing. If part of image is missing
change the display module. If the image is
otherwise corrupted, follow the appropriate
troubleshooting diagram.
Operating modes of the sub display
The display is in a normal mode when the phone is set to closed position, during incoming call/message or
other information to user.
The display is set to sleep mode soon after new information is shown.
The sub display is operated via a serial interface. Troubleshooting covers the interface between the
application processor and sub display.
Visual defects (pixel)
Pixel defects can be checked by controlling the display with Phoenix. Use both colours, black and white, on
a full screen. The display may have some random pixel defects that are acceptable for this type of display.
The criteria when pixel defects are regarded as a display failure, resulting in a replacement of the display,
are presented in table below.
Table 11 Pixel defects
Item White dot defect Black dot
defect
Total
1 Defect counts R G B White Dot
Total
1 1
1 1 1 1
2 Combined
defect counts
Not allowed.
Two single dot defects that are within 5 mm of each other should be
interpreted as combined dot defect.
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