baxter Auto Syringe AS50 Service Manual

Chapter 2 THEORY OF OPERATION
2 - 10
2.2.8 Battery Pack
The battery pack of the pump is a 5 cell 1.5 amp hour Nickel Metal Hydride pack. This
gives it a nominal 6 volt operating voltage. Actual battery voltages range from a high of 7.4
volts to 6.1 volts at the low battery threshold. Depleted battery threshold is defined as 5.5
volts. There are two parallel connections to the battery pack via the four pin connector.
The Battery + and Battery - leads terminate at P12-1(+) and P12-2(-) of the I/O board.
2.2.9 Strain Gauge Board
2.2.9.1 Strain Gauge Amplifier
• First Stage
U1A provides amplification of the strain gauge signals via an amplifier configuration that
uses the gauge as part of the amplifier. R1 sets the gain of this circuit along with the
absolute value of the gauge resistance.
• Second Stage and Zero Adjustment
R2, R3 and U1B provide a second gain stage along with an offset adjustment. The offset
adjustment is provided by R100.
• Output Range
The output at P4-5 is designed to be within the range of 0.3 volts to 4.7 volts
corresponding to -2.5lbf to 22.5lbf of force on the gauge. Voltages outside of this range
indicate either failure of the circuit or gauge or that the sensor test has been activated.
• Sensor Test
The sensor test is accomplished by pulling P4-1 to ground (on the digital board). This
connects R4 across the bridge and provides a nominal -1.15 lbf delta on the output.
During a test P4-5 may go lower than 0.3 volts if the input is at or near the -2.5lbf.
2.2.9.2 Secondary Encoder
U2 and U3 are Hall effect sensors 180 degrees out of phase that detect a magnet on the
end of the syringe driver lead screw. They provide the secondary channel of detection for
lead screw motion. Two devices are used so that a check can be performed more than
once per revolution of the lead screw.
2.2.9.3 Hg Switch
S2 is a mercury switch for monitoring of the attitude of the pump. This signal is used to
compensate for the mass of the lead screw assembly when using small diameter syringes.

baxter Auto Syringe AS50 Specifications

General

Brand	baxter
Model	Auto Syringe AS50
Category	Water Pump
Language	English