Teledyne 300M - Manual (Page 91)

Teledyne API Model 300M CO Analyzer Instruction Manual, 04033, Rev. A
9.3 Dark Current Signal Adjust Procedure
The detector dark current change is negligible as the detector ages. Therefore this procedure
should not need to be performed more than once per year or whenever a major sub-assembly is
changed. To calibrate the dark current signal, press SETUP-MORE-DIAG-DARK-CAL and
the analyzer will automatically do the following:
1. Disconnect the detector output from the signal processing electronics.
2. Wait 2 minutes for electronics to stabilize at the dark value.
3. Average CO MEAS and CO REF reading for 1 minute.
4. Reconnect the detector output to the processing electronics to the processing electronics.
The average CO MEAS and CO REF dark reading are stored as offsets which are subtracted
from all future CO detector readings.
Press SETUP-MORE-DARK-VIEW to view the current dark offset. Typical dark offset value
is 125
± 50 mV. Press EXIT when finished. No password is required to view the dark offset,
only to change it.
9.4 Output Voltage Range Changes
Output voltage ranges are set by DIP Switch settings on the V/F board. To change the range for
the analog outputs:
1. Turn off instrument power. Remove the instrument cover. Locate the V/F board near the top
of the drawing using Figure 1-2.
2. Locate switches S1, S2, and S3 along the top edge of the card. Select the desired range by
setting the switches as shown in Table 10-4.
NOTE
To adjust analog recorder offset, see Section 4.7.
9-5