Tait TM8100 mobiles Service Manual page 201

Task 9 —
Line
DIG SYN EN
TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
If the supply for the charge pump and the reference frequency are correct,
check the line input.
DIG SYN EN
1. Check the
DIG SYN EN
Enter the CCTM command 334 0 to switch off the synthesizer, and
measure the voltage at pin 10.
pin 10 of IC503: 0V DC (after entry of CCTM 334 0)
2. Enter the command 334 1 to switch on the synthesizer, and measure
the voltage again.
pin 10 of IC503: 2.5 ± 0.3V DC (after entry of CCTM 334 1)
3. If the voltages measured in
Task 10. If they are not, go to
4. Remove R104 (see
as follows:
Enter the CCTM command 334 0 to switch off the synthesizer, and
5.
measure the voltage at the via between R104 (see
the digital board.
via at R104: 0V DC (after entry of CCTM 334 0)
Enter the CCTM command 334 1 to switch on the synthesizer, and
6.
measure the voltage at the via between R104 (see
the digital board.
via at R104: 3.3 ± 0.3V DC (after entry of CCTM 334 1)
7. If the voltages measured in
digital board is faulty; replace the board and go to
page 163. If the voltages are correct, go to
8. There is a fault between the digital board and IC503. Locate the fault.
Check and resolder R104 in position (see
continuity between pin 10 of IC503 (see
board via R104.
9. If there is a fault, repair the circuit, confirm the removal of the fault,
and go to "Final Tasks" on page
could be found, replace the board and go to
page 163.
line at pin 10 of IC503 (see
Step 1 and Step 2
Step 4.
Figure 9.7) and repeat the above measurements
Step 5 and Step 6
Figure
Figure
163. If the repair failed or no fault
Frequency Synthesizer Fault Finding
Figure 9.2).
are correct, go to
Figure 9.7) and
Figure 9.7) and
are still not correct, the
"Final Tasks" on
Step 8.
9.7), and check for
9.2) and the digital
"Final Tasks" on
201