Monitor Adjustments; Lcd Zero Adjustment - GE Bently Nevada 1900/27 Operation And Maintenance Manual

1900/27 Vibration Monitor Operation and Maintenance Manual

4.2 Monitor Adjustments

Two circuits of the 1900/27 monitor may require adjustment. Since these circuits
are set at the factory, they should not require adjusting during installation.
However, if you suspect that the monitor is out of adjustment, use the following
two procedures to adjust these circuits in the monitor.

4.2.1 LCD Zero Adjustment

Use this procedure to adjust the LCD to read zero when no transducer is connected.
Because of the noise floor of the transducer, the monitor will display a low value,
less than 0.010 in./s (0.254 mm/s), when a transducer is connected and no
vibration is present. This adjustment does not affect the full scale range of the
monitor.
Adjust the LCD at an electronics workbench rather than at the installation site. A
qualified electronics technician or engineer should perform the calibration. If you
are not capable of performing this procedure, contact your nearest Bently Nevada
sales office and arrange either to send the monitor in for calibration or have
Product Service come to your facility and perform this procedure.
Setting the LCD zero requires the following tools and parts:
• A small straight blade screwdriver.
• A power source for the monitor being calibrated (110 Vac, 220 Vac, or +24
Vdc).
• A 3-conductor cable for attaching the power source to the monitor.
• Two 3 k resistors.
• Several 50 mm (2 inch), 18 AWG wires.
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