Test Products International A771 - Manual (Page 4)

BATTERY REPLACEMENT
1. Remove the single screw in the case back.
2. Slide open the battery compartment cover in the
direction of the arrow.
3. Replace the 9 volt battery and reassemble the unit.
SPECIFICATIONS
Size: 6.5” x 2.0” x 1.25”
(65 x 50 x 29mm)
Weight: 5.0 oz (142g)
Battery: 9 volt alkaline
Duty Cycle: 2,000 hours
Sensor: Long life Electrochemical
Range: 0 - 1999 ppm
Alarms: Visual, Audible
Alarm Set Range: 0-200 ppm
Calibration: 100ppm
Response Time: 90% of reading in 60 seconds
Temperature: 0 - 120 F
Relative Humidity: 5 - 95%
Accuracy: +/- 5ppm or 5% of reading,
whichever is greater
ALARM ADJUSTMENT
The alarm on the A771 is factory set at 30ppm. Use
the following procedure to select a different level
between 0 and 200ppm:
1. Remove the battery compartment cover on the
A771.
2. Using a DMM set to the DCmV range, touch the tips
of the test leads to the GND and Alarm test points on
the PCB (located on the left and right next to the
VR1 and VR2 adjustment pots).
3. Reading the DMM, set the alarm to the desired level
(1ppm = 1mV DC) by adjusting VR2.
4. Remove the leads and reassemble the A771.
CALIBRATION
1. Attach the banana jack to the COM and V input jacks
of the DMM.
2. Turn on the DMM and select the 2 or 4 volt range
DC.
3. If the voltage reading is below 4 VDC with the A771
in the off position, replace the 9 volt battery in the
A771.
4. Turn on the A771. The alarm LED with flash and the
green LED should stay on.
5. In a clean environment, adjust the zero knob until
the DMM reads zero.
6. Attach proper gas, regulator and adapter assembly
to the A771.
7. Allow to stabilize for 1 minute.
8. Adjust VR1 in the battery compartment to the
proper gas value.
9. Disconnect gas and allow A771 to zero.