TM8100 Mobile Radio Service Manual Servicing of Control Head 151
May 2004 © Tait Electronics Limited
7 Servicing of Control Head
Scope of Section This section covers servicing of the control head following the initial
investigation described in Subsection 5.2 (on page 109). The
investigation will have revealed either of the following:
■ user interface is faulty
■ control-head board needs to be replaced
The former includes faults with the two-digit display, LEDs, keys,
speaker, and volume control. Subsection 7.1 to Subsection 7.3 describe
repairs of the user interface. Subsection 7.4 describes the replacement of
the control-head board. Throughout this section data in square brackets
are grid references giving the locations of the components concerned on
the circuit diagram.
Repair of User Interface Faults in the user interface can be divided into two categories:
■ faults not involving control-head board
■ faults involving control-head board
Subsection 7.1 below and Subsection 7.2 (on page 157) cover the repair
procedures for these two cases respectively. Repair of the control-head
board, however, is a level-2 repair. Level-1 service centres should instead
replace the board as described in Subsection 7.4 (on page 163). For
level-2 service centres, Subsection 7.3 (on page 160) describes how to
find the correct replacement for a faulty component on the board. For
a discussion of SMT repair techniques, refer to Subsection 4.4
(on page 91).
7.1 Faults not Involving Control-head Board
Types of Faults This subsection gives the procedures for rectifying the following faults in
the user interface:
■ display is faulty but not LEDs
■ some but not all keys are faulty
■ speaker is faulty
■ volume control is faulty
The repair procedures are given in Tasks 1 to 5 below. A faulty display
might or might not be caused by a faulty control-head board — Tasks 1
and 2 deal with the case where the board is not the cause. The remaining
three faults also do not involve the board, and these are dealt with in
Tasks 3 to 5 respectively.
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