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4.4 Diagnosing method for damaged main parts
4.4.1 Pressure sensor
high pressure sensor 0～3.33Mpa，output 0.5～3.9V, low pressure
sensor 0～0.98Mpa, output 0.5～3.5V. Output voltage and pressure are
linear relationship.
A . High pressure Pd is abnormal: check if there is +5V voltage
between 1 and 2 pins of CN26 with multimeter, if no please check if the
PCB +5V power supply (if CMOS chip 7805 is normal) is damaged, if yes
please check if the voltage between 4 and 2 pins is within the output
voltage range(this work also can be done by the voltage meter together
with multimeter, and refer to the Pd data to analysis)
B. Low pressure Ps is abnormal: check if there is +5V voltage
between 1 and 2 pins of CN27, if no please check if the PCB +5V power
supply (if CMOS chip 7805 is normal) is damaged, if yes please check if
the voltage between 3 and 2 pins is within the output voltage range(this
work also can be done by the voltage meter together with multimeter, and
refer to the Ps data to analysis).
Note:
1）Voltage precision of common multimeter is 0.1V, so there will be
large tolerance while measuring, then you can use a good PCB to
confirm whether the pressure sensor is good or not by the reading
of rotary switch 001, 011
2）If the pressure sensor value is 0, please confirm if there still is
Part 2
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