Agilent Technologies 2948 Phase Synchronizationoption, Troubleshooting Phase Synchronization

Model 8904A Service

PHASE SYNCHRONIZATION(OPTION 005)

Description

The operation of the unit-to-unit phase synchronization circuits (Option 005 and serial prefix beginning 2948A only) is checked by monitoring the signals on the rear-panel clock synchronization and phase reset input and output lines. The checks should pinpoint the failure to either the A2 Digital Assembly or an interconnecting cable. Marginal failures may be able to be corrected by performing the Phase Synchronization Adjustment in Section 5; however, this is recommended only when there is strong reason to suspect that the failure is due to slight timing errors. Performance of the phase synchronization circuits can be verified by running the Unit-to-Unit Phase Accuracy Performance Test in Section 4.

Equipment

Digital Multimeter	................................................................ HP 3478A
Oscilloscope	HP 1740A or Tektronix 2235

Procedure

1.On the Multifunction Synthesizer, connect the rear-panel CLOCK SYNC OUTPUT to the oscilloscope input. Set the oscilloscope’s input to 500 or terminate the input in 50R using a tee.

2.On the Multifunction Synthesizer, press SHIFT PRESET. After the instrument presets, key in

SHIFT SPECIAL 7 ENTER

f2 (Status) ON

LAST

f2 (Status) ON

3.The oscilloscope should show a TTL waveform with a period of 74.5 ns (a frequency of 13.4 MHz). If faulty, check the cable which terminates at A2J9.

4.Connect the oscilloscope to A2TP1. (The oscilloscope input should remain at 50R.) Connect a short BNC cable between the rear-panel CLOCK SYNC OUTPUT and CLOCK SYNC INPUT.

5.The oscilloscope display should be the same as in step 3. If faulty, check the cable which terminates at A2J10.

6. Connect the oscilloscope input or a logic probe to the rear-panel 9 RESET OUTPUT. If an oscilloscope is used, set it to single trigger. On the Multifunction Synthesizer, press f4 (Exit).

7.Key in SHIFT iP RESET several times and observe the oscilloscope or the logic probe. The logic probe should blink a high each time. The oscilloscope should trigger a sweep each time. (It may be necessary to adjust the oscilloscope’s trigger level and the trigger may need to be armed each time.) If faulty, check the cable which terminates at A2Jll.

8.Connect a short BNC cable between the rear-panel Q, RESET OUTPUT and @ RESET INPUT. Connect the oscilloscope input or a logic probe to A2U30 pin 12.

9.Key in SHIFT iP RESET several times, as was done in step 6, and observe the oscilloscope or the logic probe. The logic probe should blink a high each time. The oscilloscope should trigger a sweep each time. If faulty, check the cable which terminates at A2J12.

rev.15DEC89 Troubleshooting (Phase Synchronization) 8-42.1