TM9100 Service Manual Frequency Synthesizer Fault Finding 183
© Tait Electronics Limited August 2005
Task 8 —
Reference
Frequency
If the supply for the charge pump is correct, check the reference frequency
input from the FCL to the PLL.
1. Measure the reference frequency at pin 8 of IC503 (see Figure 9.2).
2. If the signal is correct, go to Task 9
. If it is not, go to Step 3.
3. Check IC503 (see Figure 9.2). Replace IC503 if it is suspect.
4. Determine if the fault has been removed. If it has, go to “Final Tasks”
on page 147. If it has not, the FCL is suspect; go to “Power Supply
for FCL” on page 215.
Figure 9.6 Components between the digital board and the frequency synthesizer
VIAS FOR
MEASUREMENTS
FCL TOP CAN
pin 8 of IC503: 13.012 ± 0.002 MHz and 1.1 ± 0.2 V
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