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4-3
Section IV – Operating Instructions
OFFSET -- Pushbuttons
Two momentary action OFFSET pushbuttons allow the user to increase (+) or decrease (-) an internal
offset voltage that is applied when the instrument is in the OPERATE mode. The indication displayed on
the meter (or output at the rear panel) is the sum of the input voltage and the displayed (LCD) value of
offset voltage. The offset voltage can be varied from -30,000.00
μ
V to + 30,000.00
μ
V in 0.01
μ
V steps.
Each digit within the offset voltage display is adjusted up or down independently.
The digit to be adjusted is indicated by an underscore (e.g. 03,000.00 or 00,300.00). The position of the
underscore is selected using the INPUT OFFSET control while the padlock icon (
) is displayed to the left
of the control. Depressing and holding one of the OFFSET pushbuttons allows continuous movement of the
selected OFFSET voltage digit.
NOTE: Incrementing or decrementing a position within the displayed OFFSET voltage causes a carry to
higher order or lower order digit as appropriate. Depressing
both
OFFSET pushbuttons simultaneously
resets the offset to 00,000.00
μ
V.
NOTE: Each range has a maximum permissible offset. Exceeding this offset produces no further offset and
the
μ
V icon blinks.
OPERATE/ZERO -- Pushbutton
A momentary action pushbutton switch selects the OPERATE (measurement) or ZERO mode. In the ZERO
mode the connection between the HI input terminal and the internal amplifiers is opened, the amplifier
input is shorted to the amplifier common and any OFFSET voltage is removed. When the ZERO mode is
selected, the instrument input impedance setting (as displayed on the LCD) is replaced with ZERO. In the
OPERATE mode the voltage to be measured is applied to the input amplifier and the displayed/output
voltage is the sum of the input voltage and the indicated OFFSET voltage.
NOTE: This is NOT the button used to zero the meter.
INPUT/M
Ω
-- Pushbutton
The INPUT / M
Ω
momentary action pushbutton allows the user to select the value of resistance present
between the HI and LO input terminals. By successively depressing the momentary INPUT/M
Ω
pushbutton
increments through: 1 M
Ω
, 10 M
Ω
, 100 M
Ω
and 1 G
Ω
for ranges 100nV through 1mV, 10M
Ω
, 100M
Ω
,
from 3mV through 300V ranges 100M
Ω
1,000 V range.
NOTE: This button is not active when OPERATE/ZERO button is set to ZERO.
INPUT OFFSET -- Rotary Control/Pushbutton
This is a multi-function button and should be thoroughly understood prior to operating any other controls
on the AVM-2000.
The INPUT OFFSET rotary control is a rotary encoder that, when enabled by momentarily depressing the
control, allows the user to perform a number of zeroing functions. When the instrument is first initialized,
the control is locked. This is shown by a
(a padlock icon) adjacent to the control in the LCD. Depressing
the control once changes the padlock icon to
V
and depressing the control again changes the icon to
I
.
When
V
is displayed the control allows the user to fine tune the
current range and mode
zero position.
Turning the control clockwise moves the meter upscale and turning the control counterclockwise moves
the meter downscale. The control has a range of approximately ± full scale. The zero adjustment setting is
stored at anytime a range, zero/operate or input impedance change occurs or if the control’s position is
reset to the center or neutral position. The user can reset the control to the center (neutral—i.e. no offset)
position by depressing and holding the control depressed for 5 seconds.
