Table 10-4. Automatic Fault isolation References (1 of 2)

Suspected Circuit Indicated

Manual Procedure to Perform

by Automatic Fault Isolation

 

Check

the

YTO Loop

 

Check

1st

LO

 

Confirming a Faulty Synthesizer Section

 

 

 

 

(steps 9-11)

Check 1st LO Pretune Frequency and Amplitude Unlocked YTO PLL (steps 10-13)

Check

3rd

LO

Drive

Third LO Driver amplifier (steps l-6)

Check 10 MHz Reference to Phase Frequency

Unlocked Reference PLL (steps 8-13)

Detector

 

 

 

Check for 10 MHz Signal at Other Input to

Unlocked Reference PLL (steps 12 and 13)

Phase/Frequency Detector

 

Check A3 ADC MUX function block

Confirming a Faulty Synthesizer Section (steps l-4j

Check Al4 Frequency Control Assembly

Confirming a Faulty Synthesizer Section

 

 

 

 

(steps 12-l 7)

Check A14J301 10 MHz REF Input

Confirming a Faulty Synthesizer Section

 

 

 

 

(steps 5-8)

2heck

Al5

RF

Assembly

Confirming a Faulty Synthesizer Section

 

 

 

 

(steps 18-25)

Check

Current

Source U307

First LO Span Problems (All Spans) (steps l4-21)

Check

FM Loop Sense

Unlocked YTO PLL (steps 28-34)

Check YTF Gain and OFFset DACs

YTF Driver Circuit (steps 10-23)

Check Level at Amplifier Input

Third LO Driver Amplifier (steps l-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

Main Roller Mixer

Main Oscillator PLL (steps 10-15)

Check Main Roller Oscillator and Output Buffer Main Oscillator PLL (steps l-4)

Amp

 

 

 

 

Check

Main Roller PLL

Main Oscillator PLL (steps 16-22)

Check Main Roller Pretune DAC

Main Oscillator PLL (steps 5-9)

Clheck Main Roller Sweep/Hold Switches

First LO Span Problems 21 MHz (step 9)

Check Offset Oscillator and Buffer Amp

Offset Oscillator PLL (steps 1-3)

Synthesizer Section 10-9