218 Frequency Synthesizer Fault Finding TM9100 Service Manual© Tait Electronics Limited August 20059.9 VCXO and TCXO OutputsTask 35 —VCXO Output If the 3V power supply is not faulty, check the VCXO output as follows:1. Use an oscilloscope probe to check the VCXO output at C536 —probe the via next to C536 (see Figure 9.16). The signal should be:2. If the signal is correct, go to Task 36. If it is not, go to Step 3.3. The VCXO circuitry under the VCXO BOT can is faulty. Remove theVCXO BOT can.4. Locate and repair the fault in the VCXO (Q501, Q503, XL501 andassociated components) (see Figure 9.17).5. Confirm the removal of the fault and go to Task 36. If the repairfailed, replace the main-board assembly and go to “Final Tasks” onpage 147.VCXO output at C536: sine wave of 1.1 ± 0.2 Vpp on 1.4 ± 0.2 V DC
