Trace Oxygen Analyzer Operation 4
4-9
Teledyne Analytical Instruments
4.7 The SELF-TEST Function
The Model 3020T has a built-in self-testing diagnostic routine. Prepro-
grammed signals are sent through the power supply, output board and sensor
circuit. The return signal is analyzed, and at the end of the test the status of each
function is displayed on the screen, either as OK or as a number between 1 and
3. (See System Self Diagnostic Test in chapter 5 for number code.)
The self diagnostics are run automatically by the analyzer whenever the
instrument is turned on, but the test can also be run by the operator at will. To
initiate SELF-TEST during operation:
Use the DOWN/UP control to scroll through the MAIN MENU to SELF-
TEST. The screen will follow the running of the diagnostic.
RUNNING DIAGNOSTIC
Testing Preamp  83
During preamp testing there is a countdown in the lower right corner of
the screen. When the testing is complete, the results are displayed.
Power: OK Analog: OK
Preamp: 3
The module is functioning properly if it is followed by OK. A number
indicates a problem in a specific area of the instrument. Refer to Chapter 5
Maintenance for number-code information. The results screen alternates for a
time with:
Press Any Key
To Continue...
Then the analyzer returns to the ANALYZE screen.
4.8 The ZERO and SPAN Functions
Zeroing is not required in order to achieve the published
accuracy specification of this unit.
Zeroing will eliminate offset error contributed by sensor, elec-
tronics, and internal and external sampling system and im-
prove performance beyond published specification limits.
The analyzer is calibrated using zero and span gases.
Any suitable oxygen-free gas can be used for zero gas as long as it is
known to be oxygen free and does not react adversely with the sample system.