TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 131
May 2004 © Tait Electronics Limited
6.2 Disassembly of Control Head
Introduction This subsection covers the disassembly of control heads with UI and the
replacement of a damaged part or assembly. There are two stages in the
disassembly procedure:
■ remove control-head board
■ replace damaged part or assembly
For the latter task the control-head board must be removed. To repair
the board, removal is unnecessary unless there is a need to gain access to
components on the underside or to replace the complete board. A
separate circuit board for a concealed or dynamic microphone might or
might not be mounted on the control-head board.
Remove Control-head
Board
The procedure for removing the control-head board is as follows. Refer
to Figure 6.3.
1. Pull off the knob from the volume-control potentiometer. Do not
use any tools to do so as this might cause damage.
2. If a circuit board for a concealed or dynamic microphone is fitted,
unplug it from the control-head board.
3. If a concealed microphone is fitted, unsolder the microphone leads
from the control-head board. The leads are soldered to pads on
the board as shown in Figure 6.3.
4. Note whether the speaker leads are connected to the control-head
board. If so, disconnect the leads. The radio will need to be
returned to the Customer in its original state.
5. Use a Torx T10 screwdriver to remove the screws securing the
control-head board. The order of removal is immaterial. The
screws are labelled screw 1 to screw 3 in Figure 6.3; these numbers
are also inscribed on the PCB. The control-head board is now
held down only by the clips labelled clip 1 to clip 3 in Figure 6.3.
6. Pull upwards on the edge of the control-head board adjacent to
the speaker. At the same time push clip 1 and clip 2 by hand away
from the board. The board will lift up slightly.
7. Push clip 3 away from the control-head board while
simultaneously pressing on the shaft of the volume-control
potentiometer. The board will be freed from the space-frame.
Remove the board.
8. If the earlier inspections have not revealed any damaged parts,
continue with the repair of the radio as described in
Subsection 5.2 (on page 109). If there is damage, continue with
the disassembly of the control head and rectify the damage as
described below.
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