520 Sampler Unlocked; 521 Yo Loop Unlocked; 625 Internal Pulse Generator Unlock - Agilent Technologies PSG Series Service Manual

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
Table 1-31
right mmx connector
center mmx connector
left mmx connector
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.

625 Internal Pulse Generator Unlock

A 625 internal pulse generator unlocked message indicates a failure on the A11 Pulse/Analog Modulation
Generator.
1. Replace the A11 Pulse/Analog Modulation Generator.
Connector Signal
1 GHz >0 dBm from A7 Reference
5 GHz from A29 20 GHz Doubler -6 dBm
approx. 850 MHz >-6 dBm from A5 Sampler
Troubleshooting
Troubleshooting Unlocks
1-47