TM9100 Service Manual Frequency Synthesizer Fault Finding 197
© Tait Electronics Limited August 2005
Task 19 —
Repair Receive VCO
If either or both the minimum and maximum receive frequencies are
incorrect, the receive VCO circuitry is faulty.
1. Remove the
VCO TOP can.
2. Check the receive VCO. The circuitry is based on Q504
(see Figure 9.9).
3. If a fault is found, repair it and go to Step 4. If no fault is found, go
to Step 6.
4. Repeat the frequency measurements in Step 2 and Step 4 of Task 17
.
5. If the frequencies are now correct, resolder R542 in position
(see Figure 9.9), and go to “Final Tasks” on page 147. If they are
still not correct, go to Step 6.
6. Resolder R542 in position (see Figure 9.9). Replace the main-
board assembly and go to “Final Tasks” on page 147.
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