Tait TM9100 Service Manual page 322

If the power supply to the drains of the PAs and PA driver is not correct, the
Task 2 —
Check Switch Circuit
switch circuit is suspect. Check the circuit as follows:
1.
2.
3.
4.
5.
6.
7.
8.
If the supply from the power connector is correct, check the 9V DC supply.
Task 3 —
9V Power Supply
1.
2.
3.
4.
5.
322 Transmitter Fault Finding (25W Radios)
Measure the voltage at the point 1 on R350 shown in
The voltage should be:
point 1 on R350: 13.8V DC
If the voltage measured in
check for continuity between R350 and the power connector. Repair
any fault and conclude with
Measure the voltage at R339 as shown in
should be:
R339: 9V DC
If the voltage measured in
go to Task 3 and check the 9V power supply.
Measure the voltage at the point 2 on R350 shown in
The voltage should be:
point 2 on R350: < 5V DC
If the voltage measured in
replace Q308 — see Figure 12.3
Remove the heat-transfer block from the main board. Replace Q311
(situated on the bottom-side of the main board next to the power
connector). Replace the heat-transfer block, and conclude with
Step 8.
Repeat Task 1 to confirm the removal of the fault, and go to
Tasks" on page 147. If the repair failed or the fault could not be
found, replace the main-board assembly and go to
page 147.
Enter the CCTM command 326 1 to set the transmitter power level
very low.
Enter the CCTM command 33 to place the radio in transmit mode.
Measure the supply voltage between the 9
test point (see Figure
GND
supply 9V0 TX: 9.0 ± 0.5V DC
Enter the CCTM command 32 to place the radio in receive mode.
If the supply measured in
"Transmitter RF Power" on page
IC601 and the associated switching circuitry Q603 are suspect; go to
Task 3 of "Power Supply Fault Finding" on page
Step 1 is correct, go to Step
Step 8.
Figure 12.3. The voltage
Step 3 is correct, go to Step
Step 5 is correct, go to Step
— and conclude with
0 test point and the
V TX
12.4).
Step 3 is correct, go to Task 4
326. If it is not, the 9V regulator
158.
TM9100 Service Manual
© Tait Electronics Limited August 2005
Figure 12.3.
3. If it is not,
5. If it is not,
Figure 12.3.
7. If it is not,
Step 8.
"Final
"Final Tasks" on
in