416
Fault Finding of Control Head with Graphical Display
TM8100/TM8200 Service Manual
© Tait Electronics Limited
June 2006
14.7
Keypad Backlighting Faulty
The keypad backlighting LEDs are controlled by two FPGA signals and two
transistors (Q2), resulting in four intensity levels (off, low, medium and
high). The keypad backlighting LEDs are arranged in two groups for the
main keypad and one group for the on/off keypad, each group consisting of
three LEDs.
One LED or
One Group of LEDs
Faulty
If one LED or one group of three LEDs is faulty:
1.
Send CCTM command
1003 x
(where
x
is the intensity: 0=off,
1=low, 2=medium, 3=high) to switch on keypad backlighting.
2.
Check the 13.8V supply voltage of the relevant branch.
3.
From top to bottom, check the resistor, the three LEDs, and the
transistor of the relevant branch for continuity.
All LEDs Faulty or
Intensity Faulty
If all LEDs are faulty or the intensity is faulty:
1.
Send CCTM command
1003 x
(where
x
is the intensity: 0=off,
1=low, 2=medium, 3=high) to switch on keypad backlighting.
Figure 14.7
Circuit diagram of the keypad backlighting circuitry
R607
KEY BRIGHT0
3V3
Q2
1
47K
10K
3V3
Q2
2
47K
10K
R611
KEY BRIGHT1
13V8
R615
D608
Q603
D610
D607
R613
R30
13V8
R618
D612
Q609
D611
D609
R617
13V8
R619
D618
Q610
D606
D605
R614
FPGA
Main Keypad
On/Off
Keypad
R30: 4.7
Ω
D607: 1.9V (on)
D610: 1.9V (on)
D608: 1.9V (on)
Q603: 1.9V (on)
R615: 56
Ω
R617: 4.7
Ω
D607: 1.9V (on)
D609: 1.9V (on)
D611: 1.9V (on)
Q609: 1.9V (on)
R618: 56
Ω
R614: 4.7
Ω
D605: 1.9V (on)
D606: 1.9V (on)
D618: 1.9V (on)
Q610: 1.9V (on)
R619: 56
Ω
Summary of Contents for TM8235
Page 1: ...TM8100 mobiles TM8200 mobiles Service Manual MMA 00005 04 Issue 4 June 2006...
Page 10: ...10 TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 62: ...62 Description TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 148: ...148 Disassembly and Reassembly TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 162: ...162 Servicing Procedures TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 178: ...178 Interface Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 258: ...258 Receiver Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 446: ...446 Spare Parts TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...