HP 3400B, User'S And Service Manual

Page: 30 / 77

Warn in g
Chapter 2
calibration
Procedures
Adjustment Proced ures
Adjustment Procedures
.
-
The procedures in this section
are
used
to
adjust the voltmeter for peak
•
performance. For best performance, the voltmeter should always be
adjusted after repair.
Do
not perform the adjustment procedures unless
they
are
required. If you make unnecessary adjustments of the internal
controls, you may actually cause more difficulty.
Some procedures in this sectWn must be performed with power applied
to the voltmeter while tlul protective covers are removed To avoid
personal injury or damage
to
the instrument, do not perform procedures
in this section unless you are qualified to do so.
Note Allow the voltmeter
to
warm up for 30 minutes, with the covers
in place, before attempting any adjustments.
Front-Panel Meter Zero Adjustment
The zero adjustment screw is located on the voltmeter's front panel.
If the meter pointer does not indicate zero when power has been turned
offfor at least one minute, adjust the screw setting as described below.
1 Turn off the voltmeter and remove any input signals from the
front panel and any connections to the rear panel.
2
Allow one minute for the meter pointer
to
stabilize.
3
Rotate the zero adjustment screw clockwise until the pointer is
to
the left of zero on the meter scale. Continue adjusting until the
pointer is at zero.
If the pointer overshoots zero, repeat this step.
4 When the pointer is exactly at zero, rotate the adjustment screw
slightly counterclockwise
to
remove tension on the pointer's
internal mechanism. If the pointer moves to tlul left during this
adjustment repeat steps
3 and 4.
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