Repair Switching Network - Tait TM9100 Service Manual

If the transmit-receive switch is not functioning correctly, first check the
Task 21 —
Repair Switching
SYN TR SW
Network
board is not faulty, the switching network is suspect.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
TM9100 Service Manual
© Tait Electronics Limited August 2005
line to confirm that the digital board is not the cause. If the digital
Enter the CCTM command 335 0 to set the transmit-receive switch
off (receive mode). Measure the voltage on the
between Q508 and R593 (see
R593: 0 V DC (after entry of CCTM 335 0)
Enter the CCTM command 335 1 to set the transmit-receive switch
on (transmit mode). Again measure the voltage at R593.
R593: 2.0 ± 0.5 V DC (after entry of CCTM 335 1)
If the voltages measured in
Step 9. If they are not, remove R103 (see
Step 4.
Enter the CCTM command 335 0 and measure the voltage at the via
between R103 and the digital board (see
via at R103: 0 V DC (after entry of CCTM 335 0)
Enter the CCTM command 335 1 and again measure the voltage at
the via between R103 and the digital board.
via at R103: 3.3 ± 0.3 V DC (after entry of CCTM 335 1)
If the voltages measured in
Step 7. If they are not, the digital board is faulty; resolder R103 in
position (see Figure 9.6), replace the main-board assembly and go to
"Final Tasks" on page 147.
Check and resolder R103 in position (see
continuity between Q508 and the digital board via R593
(see Figure 9.9) and R103.
If no fault is found, go to
confirm that the voltages are now correct, and go to
page 147. If the repair failed, replace the main-board assembly and go
to "Final Tasks" on page
Check the circuitry for the transmit-receive and 5V switches (based
on Q506, Q507 and Q508) (see
If a fault is found, repair the circuit, confirm that the voltages are now
correct, and go to "Final Tasks" on page
the fault could not be found, replace the main-board assembly and go
to "Final Tasks" on page
DIG SYN TR SW
Figure 9.9).
Step 1 and Step 2 are correct, go to
Figure
Figure 9.6).
Step 4 and Step 5 are correct, go to
Figure 9.6), and check for
Step 9. If a fault is found, repair the circuit,
147.
Figure 9.9).
147. If the repair failed or
147.
Frequency Synthesizer Fault Finding
DIG
line
9.6) and go to
"Final Tasks" on
199