Agilent Technologies 8753ES Option 011 Service Manual page 320

Service Key Menus and Error Messages
Service Key Menus
Node 14 Vbb Ref (ECL reference voltage level)
Perform step A11 and then press
ANALOG IN
Meas 14 x1 Scale Ref 0.3 x1
−1.29
.
REFERENCE VALUE
x1
The trace should be a flat line across the entire operation frequency range within 0.3 V
(one division) of the reference value. Vbb Ref is used to compensate for ECL voltage drift.
Figure 10-9 Analog Bus Node 14
10-30 Chapter 10