Zero Calibration Mode - MKS HPS 937A Series Owner's Operation And Maintenance Manual

User Calibration establishes the current reading from the sensor as
the new calibration value. The calibration value is stored in non-
volatile memory and is restored when the Controller is turned on.
When user calibration is in effect for either zero or atmosphere, a U
indicator will appear next to the channels display line.

Zero Calibration Mode

To perform Factory Calibration
Turn the Function Select switch to Zero Calibration.
1
2 Set the Gauge Select switch to the desired channel.
3 Press the Factory Cal push-button to set the zero value to the factory
default.
If the sensor is still calibrated for atmosphere by the user, the U remains
visible. Otherwise, the U indicator is not displayed.
To perform User Calibration
1 Pump the system to a pressure of less than 1x10
3% of the sensors lower limit. Allow the sensor to stabilize for at
least 10 minutes.
2 Turn the Function Select switch to Zero Calibration .
3 Set the Gauge Select switch to the channel to be calibrated.
The mode indicator ZERO appears and the sensor's pressure reading
is continuously displayed. The bar graph display is activated to
indicate the difference between the sensor signal and its present zero
calibration value. For a capacitance manometer, each segment
represents .05% of full scale.
4 Press and release the User Cal push-button to save the current
vacuum reading as the new zero value. The display pressure is reset
to 0.0. and all bar graph segments are cleared. The indicator U will
appear next to the display of the channel.
A considerable zero calibration change may activate or deactivate a
sensor's set point and shift various pressure output readings.
The Series 937A Controller does not allow user calibration when the reading is
outside the appropriate range. OUT momentarily appears on the display if the
pressure is out of the allowable calibration range. In this case, the new
calibration value will not be accepted. If a previous user calibration value had
been stored, the value will be retained and the U remains visible.
The voltage of the capacitance manometer must be within ±50mV of 0V. If
the sensor voltage exceeds this range, a new calibration value will not be
accepted. Refer to the zero adjustment procedure in the capacitance
manometer instruction manual. The zero calibration of the capacitance
manometer will result in the output shifting over the full range of the head.
937A Multi-Sensor System
-5
Torr or less than
51