Tait TB7100, Service Manual

Page: 182 / 370

184 Frequency Synthesizer Fault Finding TB7100 Service Manual
© Tait Electronics Limited October 2005
Task 29 —
Repair PLL feedback
If both the maximum and minimum VCO frequencies are correct, then the
PLL feedback is suspect.
1. Resolder R542 in position (see Figure 11.12 ).
2. Remove the
VCO BOT
can.
3. Replace the components L510 (see Figure 11.13 ) and IC503
(see Figure 11.12 ).
4. Confirm that the fault in the radio has been removed. If it has, go to
“Final Tasks” on page 123 . If it has not, replace the main-board
assembly and go to “Final Tasks” on page 123 .
Figure 11.13 Synthesizer circuitry under the
VCO BOT
can (VHF radio, bottom side)
VCO BOT
1 2
3