Tait TP9100, Service Manual, Page: 205 / 326

TP9100 Service Manual
Frequency Synthesizer Fault Finding 205
© Tait Electronics Limited May 2005
9.8 Power Supply for FCL
Fault-Diagnosis
Stages
Indications of a fault in the FCL will have been revealed by the initial checks
in
“Initial Checks” on page 160 and the PLL checks in “Phase-Locked
Loop” on page 170 . In the latter case a fault with the reference frequency
input from the FCL to the PLL will imply that the FCL is suspect. Fault
diagnosis of the FCL is divided into four stages:
■
check power supply
■
check VCXO and VCTCXO outputs
■
check signals at TP501 and TP502
■
check VCXO and CODEC circuitry
The checking of the power supply is given in this section in Task 34 below.
The remaining three stages are covered in “VCXO and VCTCXO
Outputs” to “VCXO and CODEC Circuitry” on page 214 respectively.
The test and measurement points for diagnosing faults in the FCL are
summarized in
Figure 9.18 .