Instructions to replace the A/D Converter and Inguard Logic Assembly (A3)
These instructions are intended for the replacement of the A3 assembly in the 3458A that has been
diagnosed with the short term drift problem described in Service Note 3458A-18.
After completing the A3 assembly replacement the 3458A needs to be warmed up for 4 hours in
its operating environment and an ACAL ALL initiated.
The ACAL ALL will adjust the 3458A to its internal references and it will be ready to make
accurate measurements. Where necessary, a DC Gain Adjustment may be required. (see 3458A
Multimeter Calibration Manual P/N 03458-90017 on the Agilent web at:
This document contains general precautions that should be utilized when the 3458A is opened for
internal service procedures.
Only personnel with knowledge of electronic circuitry and an awareness of the hazard|