7-28 Chapter 7
Source Troubleshooting
Phase Lock Error
Figure 7-26 Typical 1st IF Waveform in FRACN TUNE/SRC TUNE Mode
A11 Phase Lock Check
At this point, the A11 phase lock assembly appears to be faulty (its inputs should have
been verified already). Nevertheless, you may elect to use the phase lock diagnostic
routines or check the relevant signals at the assembly itself for confirmation.
NOTE If external source mode is the only operating mode with phase lock problems,
replace the A11 phase lock assembly.
Phase Lock Check with PLL DIAG
Refer to “Phase Lock Diagnostic Tools” on page 7-30 for an explanation of the error
messages and the diagnostic routines. Follow the steps there to determine in which state
the phase lock is lost.
•If NO IF FOUND is displayed, confirm that the analog bus is functional and perform
“Source Pretune Correction Constants (Test 48)” on page 3-10.
• If phase lock is lost in the ACQUIRE state, the A11 assembly is faulty.
• If phase lock is lost in the TRACK state, troubleshoot source phase lock loop
components other than the A11 assembly.
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