Backlight dim or not working at all
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.
This means that in case the display is working
(image OK), the backlight is faulty.
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 the following table.
Table 5 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.
Steps
1. Verify with a working display that the fault is not on the display module itself.
The display module cannot be repaired.
2. Check that the cellular engine is working normally.
i
To check the functionality, connect the phone to a docking station.
ii Start
Phoenix
service software.
iii Read the phone information to check that also the application engine is functioning normally (you
should be able to read the APE ID).
3. Proceed to the display troubleshooting flowcharts.
Use the Display Test tool in
Phoenix
to find the detailed fault mode.
Display troubleshooting
Context
There are three different display fault cases;
1 No backlights when image is on
2 No image when backlight is on
3 No backlight and no image
RM-352; RM-354
BB Troubleshooting and Manual Tuning Guide
Issue 1
COMPANY CONFIDENTIAL
Page 3 –17
Copyright © 2008 Nokia. All rights reserved.
