ENMET SPECTRUM CO-RAL - Manual (Page 13)

S PECTRUM CO RAL ENMET Corporation
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4.2 Changing Components
Changing the sensor requires that the front of the instrument be removed; remove the four phillips head cover retaining screws,
and then the cover. See figure 5.
N OTE : The cover screws are unique to the enclosure care must be taken not to lose them.
4.2.1 Sensor Removal and Replacement
A sensor must be replaced when it no longer responds adequately to the target gas. This is indicated by a low gas concentration
reading when exposed to a known concentration of the target gas, and the inability to calibrate the instrument, with a "C-
FAULT" display after calibration. The expected sensor lifetime in normal environments is one to two years.
Remove the front cover of the instrument enclosure. Remove 2 screws that hold circuit board. Remove board. Unplug the
sensor from the circuit board,
Remove shorting spring/clip from the new sensor if needed.
Plug the new sensor in its place. Allow the sensor to stabilize in the instrument with the power on for one hour before
recalibrating.
The initial calibration of a new sensor must be performed with the front cover of the enclosure removed. Follow the procedure
for calibrating the instrument as outlined in Section 4.1.3 of this manual with the following modification.
During the application of the span gas, the counter counts down from 120. When the counter gets down to 30, adjust the
potentiometer next to the display module on the instrument PC board, so that the display to the right of the counter
reads 0.65v. This is a one-time adjustment to align the sensor output with the instrument electronics. It should only be
performed upon sensor replacement. All future calibrations should follow the procedure in Section 4.1.3.
Replace the front cover on the instrument enclosure. Calibrate the instrument according to the procedure in Section 4.1.3.
Interior View S PECTRUM CO RAL
Bottom View of Sensor
Figure 5: S PECTRUM CO RAL Sensor Location
Circuit Board
Screws, 2 places
Circuit Board Screws
2 places
Sensor
Remove shorting
clip/spring from
Sensor if present