Tait TM8100 mobiles Service Manual page 197

Task 6 —
3V Power Supply
TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
If the SMPS output and the 6V and 5V supplies are correct, the remaining
power supply to check is the 3V DC supply.
Measure the supply +3
1.
(see Figure 9.2).
pins 7 and 15 of IC503: 2.9 ± 0.3V DC
2. If the voltage is correct, go to
If it is not, go to
3. Check the supply at L506 (see
is the via shown in the figure.
L506: 2.9 ± 0.3V DC
4. If the voltage is correct, go to
IC603 is suspect; go to
page 174.
5. Check the components in the path from L506 to IC503. Also check
IC503; if necessary, replace IC503 (see
6. 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 board and go to
page 163.
0
at pins 7 and 15 of IC503
V AN
"Phase-locked Loop" on page
Step 3.
Figure 9.2). The measurement point
Step 5. If it is not, the 3V regulator
Task 3 of "Power Supply Fault Finding" on
163. If the repair failed or no fault
Frequency Synthesizer Fault Finding
Figure 9.2).
"Final Tasks" on
198.
197