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Figure 5: Faulty display
No display back light
Check VDC_OUT 3,2V DC on V406, V409, V412, V413
Check the LCD line pin 9 of N400 and cathode of V406, V409, V412, V413 Light "on"=1,2V DC ;
"off"=1,9V DC.
(Use Wintesla/ Testing/ userinterface/ 1.Test Pattern "on")
Check the LCD_light enable line on pin 7 / N400, LCD_LIGHT "on"=2,8V DC
Check the resistor R415 12K pin 8 / N400 to ground
Keypad failure
check the
mechanical
structere of the
Keymat pins
oK
check the
dome-sheet and
the PCB module if
soiled
oK
check ROW and
COL lines
connection
between the keys
version 1.0 / 05.11.1999
CONFIDENTIAL
Keypad failure
not oK
change the keymat
change the
not oK
dome-sheet and
clean the PCB
if the are some
interruption in one
not oK
line the PCB will
be faulty
Service & Analysis Center Europe
Training Team
Page 24 of 37
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