Chapter 10 517
Synthesizer Section
Troubleshooting Using the TAM
Check current source First LO Span Problems (All Spans) (steps
14-21)
Check FM loop sense Unlocked YTO PLL (steps 28-34)
Check level at amplifier Input Third LO Driver Amplifier (steps 1-6)
Check levels into mixer U400 Unlocked Offset PLL (steps 3-13)
Check loop references Unlocked Offset PLL (steps 1 and 2)
Check main coil tune DAC Unlocked YTO PLL (steps 45-49)
Check main coil coarse and fine DACs Unlocked YTO PLL (steps 41-44)
Check offset span accuracy First LO Span Problems ≤2 MHz (step 8)
Check phase/frequency detector Unlocked Reference PLL (steps 17-22)
Check path to phase/frequency detector Unlocked Offset PLL (steps 3-7, 14-19)
Check fractional N oscillator Unlocked YTO PLL (steps 14-18)
Check sampler drive output of A7 LODA Unlocked YTO PLL (steps 19-22)
Check sampler IF Unlocked YTO PLL (steps 23-27)
Check sampler/sampler IF operation Sampler and Sampler IF (steps 1-15)
Check span attenuator First LO Span Problems (All Spans) (steps
6-13)
Check sweep generator Sweep Generator Circuit
Check the 600 MHz reference loop amplifier Unlocked Reference PLL (steps 23-26)
Check the YTO loop Unlocked YTO PLL
Check YTO FM coil driver First LO SpanProblems(2.01MHzto 20 MHz)
(step 6)
Check YTO FM coil driver and main loop error
voltage driver
Unlocked YTO PLL (steps 35-40)
Table 10-5 TAM Tests versus Test Connectors
Connector
Manual Probe
Troubleshooting Test
Measured Signal
Lines
A14J15 Sweep generator MS8
Span attenuator DAC MS7
Span attenuator switches MS7
Sweep + tune mult input amp MS1, OS1
Sweep + tune mult input switches MS1, MS3
A14J16 FAV generator MS4
FAV gen 0.5 V/GHz output MS5
A14J17 Main coil coarse DAC MS3
Main coil fine DAC MS2
Main coil DACs output MS5
Table 10-4 Automatic Fault Isolation References
Suspected Circuit Indicated by Automatic
Fault Isolation
Manual Procedure to Perform
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