Cardinal Health IVAC 571, Technical & Service Manual

Page: 46 / 104

IVAC® Volumetric Pump (Models 571 & 572) 46/104 1000SM00018 Issue 2
Circuit Descriptions
Module Overview Functional Description
(continued)
Analog PCB
Consists of two separate circuits, the drop discriminator
which monitors the flow status and the pressure amplifier
which amplifies the output of the pressure transducer.

Drop Discriminator
The drop discriminator circuitry is only active when
a flow sensor is in use. The circuitry consists of a
synchronous demodulator, differential amplifier, an LED
driver, an AGC (automatic gain control) circuit and drop
simulator circuitry.

Pressure Amplifier
The pressure amplifier circuitry comprises four
functional blocks: the chopper/modulator input, the
instrumentation amplifier, the demodulator and the
output amplifier.
Accessory Interface PCB
Comprises the ultrasonic air-in-line detector and the
vacuum detection circuitry. It also acts as an interface
between the Logic PCB and various sensors and
periphery devices including the door sensor, pressure
sensor, Display PCB, motor and the rotation sensors.
Display PCB
This board comprises four 7-segment numeric displays,
two 4-digit alphanumeric modules, battery and AC
power LEDs and display circuitry which includes address
decoders, display drivers, and check circuitry. The bezel/
switch panel is an extension of the Display Board via P2.
Mechanism
The motor drives the timing pulley which in turn drives
the CAM, turning the rotation flag. The rotation flag
passes through the two rotation sensors. The function of
these two rotation sensors is to verify that the motor is
turning the correct direction.
Mains Inlet, Circuit Breaker and
Transformer
The AC line voltage is connected to the step-down
transformer through the circuit breaker. The secondary
output of the transformer provides a nominal 24 VAC
which is rectified through a full-wave rectifier, rectified
and converted into an unregulated DC voltage.
Transducer/Vacuum Assembly
The pressure transducer and the vacuum unit make up
this assembly.
Pressure measurement is detected by the pressure
sensor. Pressure sensor readings are provided by the
transducer output voltage taken from a bridge circuit
on the pressure transducer diaphragm.
A cylinder within the pump provides a vacuum to
ports surrounding the front face of the pressure
transducer to ensure firm coupling between the
pressure sensor disc pad of the IV infusion set and the
diaphragm of the transducer.
Air-In-Line Detector System
Comprises two parts: the air-in-line receiver on the front
panel and the air-in-line transmitter on the door. These
parts sandwich the IV infusion set tubing when the door
is closed and together with the air-in-line drive and
detect circuit they ultrasonically sense air in the fluid
path.