Tait TM8100 mobiles, Service Manual

Page: 236 / 620

236 Frequency Synthesizer Fault Finding TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
Task 34 —
Power Supply
If the FCL is suspect, first check that the 3V power supply is not the cause
of the fault.
1. If not already done, remove the board from the chassis and place the
radio in CCTM.
2. Measure the supply
+3
V
0
AN
at the via shown in Figure 9.17 . The via
is adjacent to the
CDC TOP
can.
3. If the voltage is correct, go to “VCXO and TCXO Outputs” on
page 237 . If it is not, the 3V regulator IC603 is suspect; go to Task 3
of “Power Supply Fault Finding” on page 174 .
via adjacent to CDC TOP can: 3.0
±
0.3V DC
Figure 9.17 TCXO circuitry under the
CDC TOP
can
IF TOP CAN
VIA FOR MEASURING 3 V DC SUPPLY