232 Receiver Fault Finding TM9100 Service Manual© Tait Electronics Limited August 2005Task 3 —Check Logic SignalIf there is no fault with the power supplies, check the logic signal DIG RX ENthat is input from the digital board.1. Check the logic signal DIG RX EN at pin 8 of IC403 (see Figure 10.2).The signal is active high. The required status is active.An alternative measurement point to the above is pin 24 of IC400under the IF TOP can (see Figure 10.1).2. If DIG RX EN is active, go to Task 4. If it is not, go to Step 3.3. Check the signal continuity from the digital board to the receiver.Repair any fault and go to Step 4. If the digital board itself appears tobe faulty, replace the main-board assembly and go to “Final Tasks” onpage 147.4. Recalibrate the receiver using the calibration application.5. Confirm the removal of the fault and go to “Final Tasks” onpage 147. If the repair failed, go to Task 7.Task 4 —Check Lock Status If the logic signal from the digital board is active, as required, check the lockstatus of the radio.1. Enter the CCTM command 72 to determine the lock status.The status should be normal:2. If the lock status is normal, go to Task 5. If the LO1 is not in lock, goto “Frequency Synthesizer Fault Finding” on page 169. If the FCL isnot in lock, go to “Power Supply for FCL” on page 215. If the LO2is not in lock, go to Step 3.3. Check the components around IC403, Q402 and Q403(see Figure 10.2). Repair any fault.4. Recalibrate the receiver using the calibration application.5. Confirm the removal of the fault, and go to “Final Tasks” onpage 147. If the repair failed go to Task 7.pin 8 of IC403: about 3.0V (active)lock status: 111 (LO1, FCL, LO2 all in lock)
