Breas PV 101+, Руководство по обслуживанию

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PV 101+/PV 102+ Service Manual ELECTRONICS
Doc. No. 003259 En Issue: X-1 BREAS MEDICAL 7–7
7.4.3 MDA board
The MDA (motor drive assembly) board comprises the driver stage for the blower motor,
the pressure sensor, the flow sensor, the hour counter and the D-shell connector for
serial communication.
The driver stage is built around the U205 control circuit and the Q205–Q210 transistors.
The P21 buzzer is powered by the C221 supercap if the mains power supply should fail.
The pressure sensor, which is of the semi-conductor type, is amplified by U201. The off-
set and gain can be adjusted using the P200 and P201 potentiometers. The signal is
used for regulating the pressure.
The flow sensor is also of the semi-conductor type, a mass flow meter. The flow that
passes the sensor is proportional to the flow through the flow resistance in the air tube
from the blower. The offset and gain can be adjusted using the P202 and P203 trim
potentiometers. The signal is used for initiating the trigger and the mask-off function.
Refer also to the circuit diagrams (See section 7.6.8, 7.6.9 and 7.6.10) and component
location drawings (See section 7.7.4).
Flow sensor
P203
Pressure
sensor
X202
X201 connector
P204
P201
P202
connector