230 Frequency Synthesizer Fault Finding TM8100/TM8200 Service Manual
© Tait Electronics Limited June 2006
9.9 VCXO and TCXO Outputs
Task 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 the
following position:
2. If the signal is correct, go to Tas k 3 6
. If it is not, go to Step 3.
3. The VCXO circuitry under the
VCXO BOT can is faulty. Remove the
VCXO BOT can.
4. Locate and repair the fault in the VCXO (Q501, Q503, XL501 and
associated components) (see Figure 9.18).
5. Confirm the removal of the fault and go to Ta sk 3 6
. If the repair
failed, replace the board and go to “Final Tasks” on page 157.
C536 — probe the via next to C536 (see Figure 9.17). The signal
should be:
VCXO output at C536: sine wave of 1.1 ± 0.2 V
pp
on 1.4 ± 0.2 V DC
A4 band: IC509, pin 4 — probe the via next to R5044
(see Figure 9.17). The signal should be:
VCXO output at pin 4 of IC509: square wave of 1.5 ± 0.2 V
pp
To Next Page
Loading...
Need help?
General
