TP9100 Service Manual Frequency Synthesizer Fault Finding 187
© Tait Electronics Limited May 2005
Task 18 —
Repair PLL feedback
If both the minimum and maximum receive frequencies are correct, the
PLL feedback is suspect.
1. Resolder R542 in position (see Figure 9.11).
2. Remove the
VCO BOT can.
3. Replace the components C567, R574 (see Figure 9.13) and IC503
(see Figure 9.11).
4. Also check the second stage of the receive buffer amplifier based on
IC404 (see Figure 9.12). Repair any fault.
5. Confirm that the fault in the radio has been removed. If it has, go to
“Final Tasks” on page 134. If it has not, replace the main board, and
go to “Final Tasks” on page 134.
Figure 9.13 Synthesizer components under the VCO BOT can (UHF radio, bottom side)
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