Tait TB8100 Service Manual page 92

Task 2 —
Check Audio Output
Using External
Signal
92 Reciter Fault Finding
1. Inject an RF test signal (1kHz audio, 60% modulation) of the
required frequency at –80dBm (22.4µV) into the antenna input.
2. Run the Service Kit and connect to the reciter. Put the reciter in
Standby mode. Select Diagnose > Reciter > Audio I/O and check
that the measured output level is the same as the level displayed on the
Audio Output gauge.
Note
The gauge will display the audio level of the balanced or unbal-
anced line out, whichever is selected in the profile of the currently
selected channel. The Level box displays the line sensitivity of the
currently selected channel. The audio output will be set to this
level during this test.
If the levels are correct, go to
brate the line levels using the Calibration Kit and repeat the test. If
the line levels are now correct, go to
If the line levels are still incorrect, either the digital board or system
interface board is faulty. If the measured output voltage is greater than
the voltage displayed on the gauge, go to
put voltage is less than the voltage displayed on the gauge, go to
Step 4.
3. Measure the audio voltages at the following test points on the digital
board:
balanced line out
unbalanced line out
Both voltages should be approximately 1V
greater than 1V
reciter to your nearest CSO for repair or replacement. If the voltages
are 1V or less, replace the system interface board.
pp
4. Measure the audio voltages at the following test points on the digital
board:
balanced line out
unbalanced line out
Both voltages should be approximately 1V
or higher, replace the system interface board. If the voltages are less
than 1V , the digital board is faulty. Return the complete reciter to
pp
your nearest CSO for repair or replacement.
Task 3.
Task
IC1020 pin 1
IC1026 pin 1
IC1005 pin 1
IC1026 pin 7.
, the digital board is faulty. Return the complete
pp
IC1020 pin 1
IC1026 pin 1
IC1005 pin 1
IC1026 pin 7.
© Tait Electronics Limited September 2006
If they are incorrect, recali-
3.
Step 3. If the measured out-
. If the voltages are
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. If the voltages are 1V
pp
TB8100 Service Manual
pp