Tait TM8100 mobiles, Service Manual

Page: 192 / 620

192 Frequency Synthesizer Fault Finding TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
Note
On A4 band radios, these components are not located under the
FCL TOP
can (see Figure 9.3 ).
Remove the
SYN BOT
can and check IC504 and IC505 for shorts
(see Figure 9.4 ); replace any suspect IC.
8. If a fault is found, repair the circuit, confirm the removal of the fault,
and go to
“Final Tasks” on page 163 . If the repair failed or no fault
could be found, replace the board and go to “Final Tasks” on
page 163 .
Task 4 —
6V Power Supply If the output of the SMPS is correct, check the 6V DC supply next.
1. Measure the supply
+6
V
0
at pin 4 of IC606 (see Figure 9.2 ).
2. If the voltage is correct, go to Task 5 . If it is not, measure the 9V
input at pin 5 of IC606 (see Figure 9.2 ).
3. If the voltage is correct, go to Step 4 . If it is not, the 9V regulator
IC601
is suspect; go to Task 3 of “Power Supply Fault Finding” on
page 174 .
4. If the input to the regulator IC606 is correct but not the output,
check IC606 (see Figure 9.2 ) and the associated circuitry; if
necessary, replace IC606 .
Remove the
SYN TOP
can and check the C-multipliers Q508 (pins 3,
4, 5) and Q512 for shorts (see Figure 9.2 ); replace any suspect
transistor.
5. If a fault is found, repair the circuit, confirm the removal of the fault,
and go to
“Final Tasks” on page 163 . If the repair failed or no fault
could be found, replace the board and go to “Final Tasks” on
page 163 .
pin 4 of IC606: 6.0 ± 0.3V DC
pin 5 of IC606: 9.0
±
0.3V DC