5-9
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be typed in from the keypad. The character most recently pressed is highlighted on the display. If
a key is pressed and it does not light up on the display, the key may be malfunctioning.
Wavelength vs AU - This stands for Wavelength vs. Absorbance Units, and is used to observe
raw detector signal. When selected the display changes to:
Ref = Smp = L = AU =
Ref is reference, Smp is sample, L is wavelength, and AU is absorbance units. The reference and
sample numbers are the raw detector signals measured by the sample and reference channels on
the detector. L refers to the wavelength being measured, and AU gives the current absorbance
being measured by the detector. These parameters should be monitored over time to see if they
change. Changes may indicate that the detector cell windows are becoming dirty, or that the lamp
strength is deteriorating.
5.3.2 Initiating and Interpreting Diagnostics
The CHDF 2000 diagnostics are explained in more detail in the following sections
Test START IN Signal Diagnostic
The Test START IN Signal diagnostic provides two functions:
•
Tests the START IN signal on the signal connector module
•
Tests the manual injector valve
Testing the START IN signal
To test the START IN signal on the signal connector module:
1.
Place the manual injector valve in the Load position.
2.
Choose Test START IN Sig. LOAD should appear in the display.
3.
Connect an insulated wire between pins 9 and 10 on the signal connector module. Check
that INJECT appears in the display.
4.
Remove the wire connection between pins 9 and 10. LOAD should reappear in the
display.
Testing the Manual Injector Valve
To test the manual injector valve:
1.
Ensure that there is no electrical connection between pins 9 and 10.
2.
Choose Test START IN Sig. LOAD should appear on the display.
3.
Place the manual injector valve in the Inject position.
4.
INJECT should appear in the display.
Press the selector knob to return to the Run Diagnostics screen.
Test Volt. Out Diagnostic
Use the Test Volt. OUT diagnostic to test the AU OUT, PRESS OUT, and %B OUT signals on
the signal connector module.
Table 5-3 identifies the expected voltages ranges of each signal.
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