Tait TP9100 Service Manual

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TP9100 Service Manual Transmitter Fault Finding 227© Tait Electronics Limited May 2005Task 5 óCheck for Inhibitingof TransmitterIf the transmitter is drawing no current or the wrong current, checkwhether it is being inhibited. This check is also required if a CO3 erroroccurs in Task 1.1. If not already done, enter the CCTM command 33 to place the radioin 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 — about2.3V — 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 — about2.8V — 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 CCTMcommand 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 relevantsection. If it is, go to Step 11.11. Check for short circuits on the DIG TX INH line from the D TX INH testpoint.12. Repair any fault, confirm the removal of the fault, and go to “FinalTasks” 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)