Hach-Lange Sigma SD900 Portable - Manual (Page 70)

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Troubleshooting
7.3.2 Keypad diagnostic
Use the keypad diagnostic to make sure each key on the keypad is
operating correctly.
Procedure:
1. Select DIAGNOSTICS > KEYPAD DIAG from the main menu.
2. Press each key on the keypad (except the BACK key). The
display should show the name of the key that was pressed.
3. To exit the test, press BACK key.
7.3.3 LCD diagnostic
Use the LCD diagnostic to make sure the controller display is
operating correctly.
Procedure:
1. Select DIAGNOSTICS > LCD DIAG from the main menu to begin
the test.
2. Observe the display. Each row will show SD900 and then each
pixel will darken. When complete, the display will briefly show
“test complete”.
7.3.4 Liquid sensor diagnostic
Use the liquid sensor diagnostic to show the current calibration
information for the liquid sensor.
Procedure:
1. Select DIAGNOSTICS > LIQ SENSE DIAG from the main menu.
2. The display will show the input frequency (MHz), the output
voltage (VDC) and the signal to noise ratio for the current
calibration.