TB7100 Service Manual Frequency Synthesizer Fault Finding 191
© Tait Electronics Limited October 2005
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 main-board assembly from the chassis
and place the radio in CCTM.
2. Measure the supply +3
V0 AN at the via shown in Figure 11.15.
The via is adjacent to the
CDC TOP can.
3. If the voltage is correct, go to “VCXO and TCXO Outputs” on
page 192. If it is not, the 3V regulator IC603 is suspect; go to Task 3
of “Power Supply Fault Finding” on page 132.
via adjacent to CDC TOP can: 3.0 ± 0.3 V DC
Figure 11.15 TCXO circuitry under the CDC TOP can
IF TOP CAN
VIA FOR MEASURING 3 V DC SUPPLY
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