Tait TP9100, Service Manual, Page: 227 / 326

TP9100 Service Manual
Transmitter Fault Finding 227
© Tait Electronics Limited May 2005
Task 5 —
Check for Inhibiting
of Transmitter
If the transmitter is drawing no current or the wrong current, check
whether it is being inhibited. This check is also required if a
CO3 error
occurs in Task 1.
1. If not already done, enter the CCTM command 33 to place the radio
in transmit mode.
2. Check the logic signal at the
TX INH
test point (see Figure 10.3 ).
The signal should be:
3. If the signal is inactive as required, go to Step 4 . If it is active — about
2.3 V — the transmitter is being inhibited; go to Step 5 .
4. Enter the CCTM command
32
to place the radio in receive mode,
and go to Task 9 .
5. Check the logic signal at the
D TX INH
test point (see Figure 10.3 ).
The signal should be:
6. If the signal is inactive as required, go to Step 8 . If it is active — about
2.8 V — the temperature sensor is suspect; go to Step 7 .
7. Enter the CCTM command 32 to place the radio in receive mode,
and go to Task 6.
8. The lock status is possibly no longer normal. Enter the CCTM
command
72
and check the lock status.
9. Enter the CCTM command 32 to place the radio in receive mode.
10. The normal lock status is
110
. If it is not, proceed to the relevant
section. If it is, go to Step 11 .
11. Check for short circuits on the
DIG TX INH
line from the
D TX INH
test
point .
12. Repair any fault, confirm the removal of the fault, and go to “Final
Tasks” on page 134 . If the repair failed or no fault could be found,
replace the main board and go to “Final Tasks” on page 134 .
TX INH test point: about 0V (inactive)
D TX INH test point: about 0V (inactive)