Tait TM8100 mobiles, Service Manual

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200 Frequency Synthesizer Fault Finding TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
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 163 . If it has not, the FCL is suspect; go to “Power Supply
for FCL” on page 234 .
Figure 9.7 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
±
0.2V
pp
A4 band: pin 8 of IC503: 2.612 ± 0.002 MHz and 1.1 ± 0.2V
pp