Agilent Technologies 8753ES Option 011 Service Manual page 250

Source Troubleshooting
Phase Lock Error
A12 Digital Control Signals Check
Several digital control signals must be functional for the A12 assembly to operate properly.
Check the control lines listed in
impedance setting.
Table 7-4 A12-Related Digital Control Signals
Mnemonic Signal Description
L ENREF L=Reference Enable
L HB L=High Band
L LB L=Low Band
L ENREF Line This is a TTL signal. To observe it, trigger on the negative edge. In
preset state, the signal should show activity similar to
Figure 7-15 L ENREF Line at A12P2-16 (Preset)
L HB and L LB Lines These complementary signals toggle when the instrument
switches from low band to high band as illustrated by
7-18
Table 7-1 with the oscilloscope in the high input
Location See Figure
A12P2-16 Figure 7-15
A12P2-32 Figure 7-16
A12P1-23 Figure 7-16
Analyzer
Setting
Preset
Preset
Preset
Figure 7-15.
Figure 7-16.
Chapter 7