Assistant Service
Manual
OPTIKON 2000
Code 121008S
6-28 Rev. D
6.3.3
VACUUM SIGNAL FILTER 369130
This small board is assembled directly behind the 141PC15G vacuum sensor
used to monitor the vacuum in the aspiration line (in the ACS3 system of the
Dual Pump Disposable Cassette). The board and sensor assembly is located
inside the Assistant, on the metal plate that supports the Disposable
Cassette and the peristaltic pump.
U1-A, while buffering the output of the sensor, also implements an
asymmetric filter with CR1, C1 and R1: the rising voltages (vacuum levels)
are not filtered but reported immediately to J1-1. The falling voltages
(decreasing vacuum levels) are filtered with the C1-R1 time constant
(0.13sec. approx.).
This arrangement allows to stop the pump immediately when the preset
vacuum level is reached (avoiding overshoots). When vacuum drops (i.e.
when occlusion is broken), the pump restarts with a minimum delay, thus
decreasing vacuum surges.
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