Equipment Description
25
Haemonetics
®
ACP-215
®
Service Manual
P/N: SM-ACP215-01-EN(AB)
During Filling Bowl, the blood pump drives the mixture of thawed RBCs and
solutions to the bowl. The pump starts at a preset maximum speed of 150 rpm
and tapers down to a preset minimum speed of 50 rpm as the bowl is filled.
Solution Pump
During Prime, adding hypertonic solution, and dilution, the solution pump
rotates (CCW) simultaneously with the blood pump to drive the solution to the
RBC bag located on the shaker. See
and
.
During Filling Bowl, or transferring blood product from the bowl back to the RBC
bag, the solution pump is stopped.
Circuit Description
Both pumps on the device function identically. The following circuit description
refers to the blood pump circuit located on the Driver PCB Assembly, part
number 36557-02.
Set Point Interface
The pumps are controlled using step and direction digital input signals. The
step signals, M1 and M2, are derived from a 2-MHz reference clock using the
programmable counters of U70. The direction signals are obtained from data
bits by U65. The step and direction signals are optically isolated by U56,
conditioned, and then applied to the GL-1200 controller U61.
GL-1200
This controller IC uses the pulses from U56 and the buffered encoder feedback
signals of +5 VDC to calculate the position error (the difference between the
desired and actual position). This error is processed by the GL-1200 to produce
three TTL outputs: MC, SD1, and SD2. MC is a PWM position error signal. SD1
and SD2 are logic signals that represent the derivative of the position error.
Compensation
U30 is used to sum and shape the position and derivative outputs of the GL-
1200 in order to implement a PD (proportional and derivative) control system.
Power Amplifier
The motor power stage is implemented with an L292 PWM driver, U12. This
driver is capable of supplying ±2.25 A to the motor. To insure reliability, the heat
sink temperature is measured and compared to a 90 degree Celsius threshold
by U13 and U23. The CPU monitors the compare signal and can respond to an
overheating condition.
