Tait TB8100 Service Manual page 93

Task 3 —
Check Audio Input
TB8100 Service Manual
© Tait Electronics Limited September 2006
1. Connect a 1kHz audio signal to the balanced input (LINE INPUT)
on the CTU. Set the level of the audio signal to the level of audio
input sensitivity of the currently selected channel.
Note
To view the audio input sensitivity of the currently selected chan-
nel, select Configure > Base Station > Channel Profiles. In the
Edit Channel Profile screen, go to the Signal Path tab. The sensi-
tivity is normally –10dBm for the balanced input, and 1V
the unbalanced 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 level displayed in the Audio Input gauge is the same as the
input level of the audio signal.
3. Reconnect the audio signal to the unbalanced input (UB INPUT) on
the CTU.
4. Select Diagnose > Reciter > Audio I/O and check that the level
displayed in the Audio Input gauge is the same as the input level of
the audio signal.
5. If either audio input level is incorrect, recalibrate the line levels using
the Calibration Kit and repeat the test. If the line levels are now
correct, go to "Final Tasks" on page
If the line levels are still incorrect, either the digital board or system
interface board is faulty. If the voltage displayed on the gauge is
greater than the measured input voltage, go to
displayed on the gauge is less than the measured input voltage, go to
Step 7.
6. Measure the audio voltages at the following test points on the system
interface board:
balanced line in
unbalanced line in
Both balanced line in voltages should be approximately 0.5V
voltages are greater than 0.5V
If the voltages are 0.5V
the complete reciter to your nearest CSO for repair or replacement.
The unbalanced line in voltage should be approximately 1V
voltage is greater than 1V
voltage is 1V
pp
plete reciter to your nearest CSO for repair or replacement.
95.
IC206 pin 1
IC211 pin 7
IC202 pin 7
, replace the system interface board.
pp
or less, the digital board is faulty. Return
pp
, replace the system interface board. If the
pp
or less, the digital board is faulty. Return the com-
pp
Step 6. If the voltage
. If the
pp
. If the
pp
Reciter Fault Finding
for
93