Incorrect Dew Point Display - GE Optica Operator's Manual

Chapter 7. Maintenance

7.4.3 Incorrect Dew Point Display

If the dew/frost point reads incorrectly, first check the standard preventive maintenance items:
•
Clean and balance the sensor mirror (refer to "Cleaning and Balancing the Sensor Mirror" on page 75).
An alternative method for checking the accuracy of the unit's electronics is to use a precision resistance decade box in
place of the platinum thermometer. Wire the decade box to the unit's sensor connector as shown in Figure 49 below,
and verify that the resistance settings shown in the table produce the temperatures shown.
82
HIGH LOW
Resistance
Decade Box
RX100
RX10
Din Type 100 Ohms at 0°C 0.385 Ohms/°C
Resistance
RX1
Ohms
76.33
RX0.1
96.09
100.00
103.90
RX0.01
123.24
Figure 49: Using a Resistance Decade Box
Optica
J
1123HK
K
Sensor
T
Cable
L
Connector
Optica
7
D2
15
Sensor
8
Cable
14
Connector
Resistance Table
Display Reading
°C (±0.1) °F (±0.2)
–60.0 –76.0
–10.0 14.0
0.0 32.0
10.0 50.0
60.0 140.0
Optica™ Operator's Manual