3V Power Supply - Tait TM9100 Service Manual

If the SMPS output and the 6V and 5V supplies are correct, the remaining
Task 6 —

3V Power Supply

power supply to check is the 3V DC supply.
1.
2.
3.
4.
5.
6.
180 Frequency Synthesizer Fault Finding
Measure the supply +3 0
V
(see Figure 9.2).
pins 7 and 15 of IC503: 2.9 ± 0.3V DC
If the voltage is correct, go to
is not, go to Step 3.
Check the supply at L506 (see
is the via shown in the figure.
L506: 2.9 ± 0.3V DC
If the voltage is correct, go to
IC603 is suspect; go to Task 3
page 158.
Check the components in the path from L506 to IC503. Also check
IC503; if necessary, replace IC503 (see
If a fault is found, repair the circuit, confirm the removal of the fault,
and go to "Final Tasks" on page
could be found, replace the main-board assembly and go to
Tasks" on page 147.
at pins 7 and 15 of IC503
AN
"Phase-locked Loop" on page
Figure 9.2). The measurement point
Step 5. If it is not, the 3 V regulator
of "Power Supply Fault Finding" on
Figure 9.2).
147. If the repair failed or no fault
© Tait Electronics Limited August 2005
181. If it
"Final
TM9100 Service Manual