Tait TM8100 mobiles Service Manual page 181

Task 1 —
Check Output Lines
TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
For an output line suspected or reported to be faulty, compare actual and
expected signals as described below. If necessary, determine what an
expected signal should be by copying the faulty radio's programming file
into a serviceable radio and measuring the relevant points on the latter.
1. Check the electrical signal at the appropriate pin of a connector
mated to the radio connector in question. If the expected connector
signal is not present, go to
2. If the expected signal is present, there might be no fault on that line
or there could be an intermittent fault. Subject the radio to mild
mechanical shock or vibration, or to a temperature change. This
might expose any intermittent contact, in which case go to
3. If the expected signal is not present, check whether the expected
internal signal is present. If it is, go to
4. 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
and "CODEC and Audio Fault Finding" on page 399
the digital board is suspect, replace the board and go to
on page 163.
5. The fault lies in the filtering, basic processing, or connector for the
line under test. Re-solder components or replace damaged or faulty
components as necessary. Confirm the removal of the fault and go to
"Final Tasks" on page
the board and go to
Step 3. If it is, go to
Step
"Power Supply Fault Finding" on page 169
163. If the fault could not be found, replace
"Final Tasks" on page
Interface Fault Finding
Step 2.
Step
5. If it is not, go to Step
respectively. If
"Final Tasks"
163.
3.
4.
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