16
1142A Probe Control and Power Module
Service
Troubleshooting
The circuitry consists of simple power supplies, operational
amplifiers, and TTL logic. Use conventional troubleshooting
techniques. A complete parts list, component location, and
schematics are provided later in this chapter.
Theory of Operation
The following discussion covers block- level theory for the 1142A
Probe Control and Power Module.
The control and power module provides offset functions, local and
remote control, and power to an 1141A Differential Probe. For
more complete information about how this power module is used
with the differential probe, see the service section of the user and
service guide for the probe.
Offset Functions
There are two offset functions developed in the control module:
variable offset and dc reject. A variable offset voltage with coarse
and fine adjustments can be selected by the front panel controls.
The offset level is buffered by U8 and selected by multiplexer U3 as
the input to offset amp U7. The output of the offset amp is
summed with the low frequency signal and feedback which gives dc
coupling in the probe.
Summary of Contents for 1142A
Page 1: ...Agilent Technologies Agilent 1142A Probe Control and Power Module User s Guide...
Page 29: ...1142A Probe Control and Power Module Replaceable Parts 29 Figure 7 Schematic 1...
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