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Troubleshooting
Troubleshooting Unlocks
515 10 MHz Signal Bad
A 515 10 MHz Signal Bad message indicates a problem on the A7 Reference.
A7 Reference (Standard)
• Replace the A7 Reference.
A7 Reference (Option UNR)
1. Check the 10 MHz signal into the A7 Reference from the 10 MHz standard.
2. The signal should be 10 MHz 1.8 V
pp
into 1 MΩ.
3. If the 10 MHz signal is bad, replace the A32 10 MHz Crystal Oscillator.
4. If the signal is good, replace the A7 Reference.
520 Sampler Unlocked
A 520 Sampler unlock message indicates a failure of the A5 Sampler VCO loop.
1. Run self–test. If self–test fails, troubleshoot the problem reported.
2. Power–up the signal generator. Remove the A5 Sampler. Probe the mmx connection center pin
on the right side of the A31 Motherboard in the A5 Sampler slot. There should be a 1 GHz signal
>0 dBm.
3. If the 1 GHz signal is present, replace the A5 Sampler.
4. If the 1 GHz signal is not present, replace the A7 Reference.
NOTE Turn the signal generator off before re–installing any assembly.
521 YO Loop Unlocked
A 521 YO Loop unlocked message indicates a failure of the A5 Sampler’s YO Phase detector circuit.
1. Set the signal generator to 5 GHz.
2. With the signal generator on, remove the A5 Sampler. Probe the mmx connectors on the A31
Motherboard
3. If all signals are present replace the A5 Sampler.
4. If any signal is not present, troubleshoot to the signal generator and replace that assembly.
NOTE Turn the signal generator off before re–installing any assembly.
Table 1-14
Connector Signal
right mmx connector 1 GHz >0 dBm from A7 Reference
center mmx connector
5 GHz from A29 20 GHz Doubler
–6 dBm
left mmx connector
approximately 850 MHz >
–6 dBm from A5 Sampler
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