RKI Instruments NP-204 - Manual (Page 6)

NP-204 RKI Instruments, Inc.
switch is in this position the instrument
will detect and display the high range only.
2 . ZERO ADJ.
This adjustment is used to Zero the reading for the LOW range. This is generally done
before each use of the instrument. (The zero adjustment for the % gas range only
rarely needs adjustment, so is not externally adjustable).
3 . VOLT ADJ.
This adjustment is used to set the voltage for the detectors. When the “RANGE” switch
is in the “Volt Adj.” position, this knob can be turned to bring the meter reading to
match the red “V” line, which sets the detector voltage to the proper level.
4. LIGHTS
L When this light is lit, it indicates that the
instrument is turned on and that the LOW
range sensor is energized.
H This light indicates that the HIGH range
sensor is energized.
5. Meter Mechanical Zero
Located centered directly below the meter, this adjustment is used if necessary to
adjust the meter Mechanical Zero while the power is turned off to the instrument.
Battery Compartment
The NP-204 battery compartment is located on the bottom of the instrument. It has a removable panel
for easy replacement of the batteries. The panel is held in place by one screw located on the bottom of
the instrument.
The NP-204 uses two “D” size cells; alkaline batteries will run the NP-204 for approximately 5
hours, rechargeable nickel-cadmium batteries will run for approximately 4 hours. (Rechargeable
batteries must be removed from the NP-204 and charged separately.)
Circuit Boards
The NP-204 has one circuit board. The circuit board contains the screw connectors for the replaceable
detectors, adjustment potentiometers for High range Zero and Span and for Low range span, and wiring
to the external switches and adjustments. The circuit board is internally mounted directly to the back of
the meter.
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