HP 3457A Service Manual page 167

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SECTION VIII
SERVICE
8-1. INTRODUCTION
This section contains information to aid in troubleshooting and repair of the HP 3457A_ Digital
Multimeter. Included are safety considerations, theory of operation and troubleshooting procedures.
The information contained in this section is intended for the use of service (rained per-
sonnel who understand electronic circuitry and are aware of the hazards involved. Do
not attempt to perform any of the procedures outlined in this section unless you are
qualified to do so.
8-2. SAFETY CONSIDERATIONS
The HP 3457A is designed to meet international safety standards. To maintain these standards, the cau-
tions, warnings, and other safety related information contained in this manual must be followed.
Servicing of this instrument must be performed by service trained personnel.
Any interruption of the protective grounding conductor (either inside or outside the in-
strument) or disconnection of the protective earth terminal will likely make the instru-
ment dangerous. Intentional interruption of the protective grounding conductor is
strictly prohibited.
The service information contained in this section normally requires removal of the
protective covers and application of power. Voltages or signals at many pointy within
the instrument may, if contacted, result in personal injury.
To protect personnel and prevent damage to the instrument, adjustment or repair with covers removed
and power applied must be avoided as much as possible. When it becomes necessary to service the in-
strument under these conditions, the work must be performed by a skilled person who is aware of the
hazards involved.
Be certain that only the recommended fuse type (correct current rating, etc) is used for replacement.
The use of repaired fuses or short circuiting the fuse holder is prohibited.
HP 3457A Multimeter
8-1