Phase-Locked Loop Description; Supply For Charge Pump - Tait TM9100 Service Manual

9.3 Phase-locked Loop
If there is no fault with the power supplies, check the critical output from,
Introduction
and inputs to, the PLL:
The measurement points for diagnosing faults concerning the PLL inputs
and output are summarized in
First check the supply for the charge pump of the PLL.
Task 7 —
Supply for
Charge Pump
1.
2.
3.
4.
TM9100 Service Manual
© Tait Electronics Limited August 2005
Task

7: supply for charge pump

Task 8: reference frequency input
Task 9: line input
DIG SYN EN
Task 10: line output
SYN LOCK
Measure the supply for the charge pump at pin 16 of IC503
(see Figure 9.2).
pin 16 of IC503: 5.0 ± 0.3 V DC
If the voltage is correct, go to
Check the C-multiplier Q512 (see
itself; if necessary, replace the transistor or IC.
If there is a fault, 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.
Figure 9.5.
Task 8. If it is not, go to
Figure 9.2) and check IC503
147. If the repair failed or no fault
Frequency Synthesizer Fault Finding
Step 3.
"Final
181