Tait TM8100 mobiles Service Manual page 239

Task 36 —
TCXO Output
Figure 9.19 FCL circuitry under the VCXO BOT can
CAN FOR
DIGITAL
BOARD
TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
If the VCXO output is correct, check the TCXO output as follows:
1. Use the oscilloscope probe to check the TCXO output at the
test point (see
TCXO output at TP504 test point: clipped sine wave of 1.0 ± 0.2V
2. If the signal is correct, go to
page 240. If it is not, go to
3. The TCXO circuitry under the
can.
CDC TOP
4. Locate and repair the fault in the TCXO (XL500 and associated
components) (see
5. Confirm the removal of the fault and go to
TP502" on page
"Final Tasks" on page
CDC BOT CAN
Figure 9.18). The signal is
"Signals at TP501 and TP502" on
Step 3.
CDC TOP
Figure 9.17).
240. If the repair failed, replace the board and go to
163.
Frequency Synthesizer Fault Finding
TP
and should be:
SYN RX OSC
pp
can is faulty. Remove the
"Signals at TP501 and
SYN BOT CAN
504
239