ENMET SPECTRUM ON-LINE - Manual (Page 11)

Spectrum ON-LINE ENMET Corporation
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4.1.1 Key
Entrance to the maintenance menu is guarded with a four digit numerical key. The factory default setting of the key is
1270(The process by which a different key is set is given in paragraph 4.1.5, below). When the valid numerical key is
inserted, the user is allowed to enter the maintenance menu.
When in the "go SETUP" location, press the SELECT pushbutton; "Key=0000" is displayed. The underscore cursor is
under the left hand digit. To insert the key, press the OPTION pushbutton to change the left hand digit, and choose the
correct digit; then press the SELECT pushbutton, which locks in the chosen left hand digit and moves the underscore
cursor one space to the right. Continue this process until the four digit key is complete. When the valid key is inserted
in this manner, the display is transferred to the "run ZERO" portion of the maintenance menu. When an invalid key is
inserted, "INVALID" is briefly displayed, and the instrument returns to the operational display.
4.1.2 Zero
A valid key entry sets the instrument at the "run ZERO" location, of the maintenance menu, which enables the setting
of the zero gas concentration point. This is desirable if the zero reference of the gas sensor has drifted over a period of
time, indicated by a persistent gas concentration reading in a clean environment. Note that the calibration sequence
given below also includes setting the zero point. If a full calibration is required, instead of setting just the zero point,
push the OPTION button once; "run CAL" is displayed. See paragraph 4.1.3, below.
To set the zero point without performing full calibration, from the "run ZERO" location press the SELECT pushbutton;
"AIR SET?" is displayed. Be certain that the instrument is in clean air, uncontaminated by the target gas. If uncertain
of the environment, use pure compressed air from a pressurized cylinder, and flow it over the sensor at a low rate.
With the instrument in “AIR SET?”, press the SELECT pushbutton again. "z30:0.0v" is displayed; this is a counter
that counts down in seconds from 30 to 0. The validity of the new zero setting is then examined; if it is with in preset
parameters, the display is transferred to the operational display in the operation menu.
If the new zero setting is not between preset parameters, "C-FAULT" is displayed. Unplugging and then plugging in
the power supply turns the instrument OFF, then ON again. This re-boots the system with the most recent valid zero
setting.