Analog Bus Nodes - Agilent Technologies 8719ET Service Manual

Service Key Menus and Error Messages
Analog Bus on OFF
FRAC N
DIV FRACN

Analog Bus Nodes

The following paragraphs describe the 23 analog bus nodes. They are listed in numerical
order and are grouped by assembly. For node locations, refer to the "Overall Block
Diagram," in Chapter 4
Press
SERVICE MENU
System
ANALOG IN AUX INPUT
bus node. Terminate the entry by pressing
A10 Digital IF
1. +0.37V (+0.37V reference)
Check for a flat line at approximately +0.37V. This is used as the voltage reference in
the Analog Bus Correction Constants adjustment for calibrating out the analog bus
high/low resolution gain and offset errors. The absolute voltage level is not critical, but
it should be the same in high and low resolution.
2. +2.50V (+2.50V reference)
Check for a flat line at approximately +2.5V. This voltage is used in the Analog Bus
Correction Constants adjustment as a reference for calibrating the analog bus low
resolution circuitry.
3. Aux Input (Rear panel input)
This selects the rear panel AUX INPUT to drive the analog bus for making voltage and
frequency measurements. It can be used to look at test points within the instrument on
the display (using the display as an oscilloscope). Connect the test point of interest to
the AUX INPUT BNC connector on the rear panel. This feature can be useful if an
oscilloscope is not available. Also, it can be used for testing voltage-controlled devices by
connecting the driving voltage of the DUT to the AUX IN connector. You can look at the
driving voltage on one display channel while displaying the DUT S-parameter response
on the other display channel.
With turned ON, you can examine analog bus nodes with external
AUX OUT
equipment (see
AUX OUT on OFF
"Overall Block Diagram," in
Service Mnemonic Definitions" on page
4. A10 Gnd (Ground reference)
This is used in "Analog Bus Correction Constants (Test 44)" on page 3-8
for calibrating the analog bus low and high resolution circuitry.
10-22
switches the counter to monitor the A14 fractional-N VCO
frequency at the node shown on the "Overall Block
Diagram," in
switches the counter to monitor the A14 fractional-N VCO
frequency after it has been divided down to 100 kHz for
phase locking the VCO.
.
ANALOG BUS ON
, and then use the front panel keys or knob to select an analog
x1
in "Analog In Menu" on page
Chapter 4 . For GPIB considerations, refer to
10-31.
Chapter 4 , "Start Troubleshooting Here."
Meas
.
8719ET/20ET/22ET
8719ES/20ES/22ES
RF Network Analyzers
10-21). See the
"GPIB
as a reference
Service Guide