5.6.2 Vacuum circuits.
The vacuum is measured by means of the vacuum sensor S101 (wheatstone bridge). The measured
value is compared with the set value (VACSET ) by U102A and a PWM generator (U102B) controls
the pump when necessary.
The vacuum intensity can be set by means of a knob on the front of the unit (VACSET signal).
When the measured vacuum is higher than the set vacuum, the rhythm valve will be open until the
vacuum reaches its normal level (Vvac)
Both the channels A and B have their own valve which means that each vacuum channel can be
selected separately (VAC/NRM A and VAC/NRM B).
When a pulsed vacuum treatment is selected, the V-Rhythm signal will open and close the rhythm
valve in accordance with the pulse selection.
All valves are Normally Closed and will be opened by means of a 24 VDC signal.
The water level in the reservoir is checked on constant base. A block signal, produced by U107, is
presented to one of the metal detection pin inside the reservoir. If the water reaches a certain level,
this signal will be transmitted to the second detection pin.
This signal is picked up by U106, and a signal is given to the microprocessor via the H2O level line.
If the microprocessor detects a full reservoir, the following message on the screen appears ‘water
reservoir full’. It is still possible to continue the treatment.
If the message appears before the treatment is started, it is impossible to switch on the vacuum unit.
Phyaction Guidance E/C – service manual version 0.5 Page 23
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