Tait TP9100 - Chapter 7: Interface Fault Finding; Front Panel Keypad and LCD Faults

TP9100 Service Manual Interface Fault Finding 139
© Tait Electronics Limited May 2005
7 Interface Fault Finding
Overview This section describes fault finding of the user interface and accessories
interface connector. User interface fault finding includes the following:
■ Front panel keypad. This includes the numeric keypad, scroll and
selection keys, and keypad backlighting.
■ LCD. This includes the LCD display and LCD backlighting.
■ Top and side of radio. This includes the ON/OFF switch, volume control,
3-way and 16-way selectors, status LED indicators, function keys and
PTT, and internal speaker/microphone.
The faults can be detected by visual inspection (refer to “Initial Tasks” on
page 127) or using CCTM commands (refer to Table 4.7 on page 96).
General The following notes apply to all interface fault finding procedures:
■ For disassembly and reassembly instructions, see “Disassembly and
Reassembly” on page 101.
■ After completing the repair, carry out the tasks in “Final Tasks” on
page 134.
■ The main-shield assembly and LCD assembly are non-serviceable items,
and must be replaced in their entirety if faulty. For more information
refer to “Spare Parts” on page 289.
Tas k 1 —
Front Panel Keypad
Faulty
Use this procedure for faults with numeric keys, scroll keys, selection keys
or keypad backlighting. Before proceeding, make sure the fault is not an
issue with programming. For backlighting faults, make sure backlighting is
enabled in the programming application. For keypad faults (16-key models
only), make sure full keypad functionality is enabled via the Software Feature
Enabler in the programming application.
If the keypad is faulty:
1. Remove the front panel.
2. Remove the main-shield assembly, and fold the assembly open leaving
the loom connected between the front panel and the main board.
3. Check the integrity of the front-panel loom and confirm it is seated
correctly at both ends (
RADIO and KEYPAD).
4. Reassemble and power-up the radio. Check the functionality of the
keypad.
5. If still faulty, remove the front panel and replace the front-panel loom
with a known good one.
6. Reassemble and power-up the radio. Check the functionality of the
keypad.