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CCS Technical Documentation
Backlight troubleshooting (3)
Start
Enable backlight
and try with
another display
module
Backlight OK?
Yes
No
Check current mirror
components:
V4421, R4436, N4421, R4443
and backlight power
components:
R4441, R4442, R4446
V28 should be found from
C4438.
Check connector X4421
soldering.
Backlight OK?
69
END
Replace display
module. Calibrate
touchscreen.
If upper backlight leds
are not working / are
dimm, but lower are
bright => problem in
current mirror circuitry
No
END
COMPANY CONFIDENTIAL
Copyright © 2004 Nokia. All Rights Reserved.
R4446 =
0.50-0.51V
No
& R4442 =
1.50-1.51V?
Yes
R4441 should have also
0.50-051V. If not, replace
1st V4421, 2nd N4421
3rd R4436 & R4443 &
R4435
Backlight OK?
No
PWB failure
RM-12
Goto backlight
power troubleshooting
page 2
END
Issue 1 11/2004
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Table of Contents
Troubleshooting
