Offset in the SL1 Meter and the SL103 Differential Amplifier must be removed.
The meter offset is eliminated by switching on the SL1, shorting the input sockets and the SET ZERO is used to zero the pointer. Remove these connections.
The SL103 Differential Amplifier output offset is cancelled by shorting together the two input sockets and then connecting both to ground. Adjust the SET ZERO control so that the output from the amplifier is zero when measured on the meter in the SL1. Remove these connections and switch off the SL1. Set up the equipment as shown in Figure4.6 and switch on.
With the balanced DC supply adjusted to approximately 1V,use the balance control on the SL105 to zero the meter . set balance DC supply to minimum. Close the pressure release valve.
Increase the Low Voltage Power Supply until the pressure in the pressure indicated by the Bourdon Gauge is 100kPa, Adjust the ba lanced DC supply to produce FSD on the 1V range.Open the pressure release valve and check that zero pressure gives zero deflection on the SL1 meter.
Increase the pressure gradually by controlling the pump speed and record corresponding values of pressure and meter reading in the table provided.