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Only for training and service purposes
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4. TROUBLE SHOOTING
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4.7 Keypad Backlight Trouble
MAIN Key Pad LED is on as below :
Key pressing -> main key backlight goes down low (below 0.8v) -> MAIN Key Backlight LED On
Check the TP1 voltage
-TP1 = Above 0.8 V
Figure 4.7.1 Keypad Backlight Trouble Circuit
R107
100
VA100
C101
1u
LD100
100
R106
R105
100
R103
100
100
R102
R101
100
100
R100
100
R104
LD101 LD102 LD103 LD104 LD105
VBAT
LD107
LD106
MAIN_KEY_BACKLIGHT
TP1