HP 8753E Service Manual page 352

Check the 4 MHz REF Signal
1. Press w.
2. Use an oscilloscope to observe the 4 MHz reference signal at AlOP2-6.
If the signal does not resemble Figure 8-3, troubleshoot the signal source
q
If the signal is good, the probability is greater than 90% that the A10
q
assembly is faulty. For confirmation, perform "Check A10 by Substitution
or Signal Examination".
-500.000 nmec
0 . 0 0 0 0 0 ma0
Figure 8-3. 4 MHz RJIF Waveform
Receiver Troubleshooting 8-7
I