TM8100 Mobile Radio Service Manual Diagnosis of Faults on Main Board 183
May 2004 © Tait Electronics Limited
7. The fault lies with the radio’s internal circuitry. If the power-
supply circuitry or the CODEC and audio circuitry is suspect,
continue with the fault diagnosis as in Subsection 9.1 and
Subsection 9.7 respectively. If the digital board is suspect, return
to Subsection 8.1 and replace the complete main-board assembly.
8. The fault lies in the filtering, basic processing, or connector for the
line under test. Re-solder components or replace faulty com-
ponents as necessary. Confirm the removal of the fault and return
to Subsection 8.1. If the fault could not be found, return to
Subsection 8.1 and replace the complete main-board assembly.
Tas k 3 —
Bi-directional Lines
For a bi-directional line suspected or reported to be faulty, proceed as
described below. In the procedure the direction of the line will need to
be configured. For information on this topic consult the on-line help
facility on the programming application’s “Programmable I/O” page.
1. Configure the suspect line as an output, and then carry out the
procedure given in Task 1.
2. Configure the suspect line as an input, and then carry out the
procedure given in Task 2.
9.3 Frequency Synthesizer
Introduction This subsection covers the diagnosis of faults in the frequency
synthesizer. The synthesizer is a closed-loop control system. A fault in
one area can cause symptoms to appear elsewhere. Locating the fault can
therefore be difficult. The fault-diagnosis procedure is divided into four
tasks. First discussed, however, is the lock status of the radio, which will
indicate whether or not the synthesizer is suspect.
Lock Status The lock status of the radio might already have been determined as part
of the preliminary fault diagnosis. The following is a summary:
1. Enter the CCTM command 33 to place the radio in transmit
mode. Enter the command 72 to determine the lock status in this
mode. Note the response. The normal status is 110.
2. Enter the CCTM command 32 to place the radio in receive mode.
Enter the command 72 to determine the lock status in this mode.
Note the response. The normal status is 111.
3. If the lock status in either or both receive and transmit mode is
a0a, where a is 0 or 1, the FCL is suspect; go to Subsection 9.4.
4. If the lock status is 011 or 010 in receive mode or 010 in transmit
mode, the synthesizer is suspect; proceed to Task 1. (If the status
is 010 in receive mode, investigate the receiver later also.)
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