Mitsubishi Electric e Series Service Handbook page 129

[ IX Troubleshooting ]
Low-Pressure Sensor
-2- Low pressure sensor (63LS)
1. Perform a check while comparing the pressure detected by the low pressure sensor with the pressure of the low
pressure gauge.
When the digital display changeover switch (SW4) is set as follows, the detected pressure of the low pressure sensor
is displayed on the LED (LD1).
(1) Compare the gauge pressure and the pressure displayed on the LD1 while the operation is stopped.
1) When the gauge pressure is about 0 - 0.098 MPa → Internal pressure drop due to gas leakage
2) When the pressure displayed on the LD1 is about 0 - 0.098 MPa → Check the connector for contact failure and disconnection
and see (4)
3) When the pressure displayed on the LD is 1.7 MPa or above → See (3)
4) When any of 1) to 3) do not apply, compare the pressure during operation → See (2)
(2) Compare the gauge pressure and the pressure displayed on the LD1 during operation. (Compare using MPa unit)
1) When the difference in pressure is within 0.03 MPa → The low pressure sensor and the main circuit board are normal
2) When the difference in pressure is over 0.03 MPa → The low pressure sensor is malfunctioning (characteristic deterioration)
3) When the pressure displayed on the LD1 does not change → The low pressure sensor is malfunctioning
(3) Remove the low pressure sensor from the main circuit board and check the pressure displayed on the LD1.
1) When the pressure displayed on the LD1 is about 0 - 0.098 MPa → The low pressure sensor is malfunctioning
2) When the pressure displayed on the LD1 is about 1.7 MPa → The main circuit board is malfunctioning
(4) Remove the low pressure sensor from the main circuit board, short-circuit 2-3 of the connector (63LS), and check
the pressure displayed on the LD1.
1) When the pressure displayed on the LD1 is 1.7 MPa or above → The low pressure sensor is malfunctioning
2) When 1) does not apply → The main circuit board is malfunctioning
(5) Remove the high pressure sensor (63HS) from the main circuit board, connect the sensor to the connector for the
low pressure sensor (63LS), and check the pressure displayed on the LD1.
1) When the pressure displayed on the LD1 is 1.7 MPa or above → The main circuit board is malfunctioning
2) When 1) dose not apply → The low pressure sensor is malfunctioning
2. Low pressure sensor structure
The low pressure sensor consists of the circuit shown on the right.
When 5 VDC is applied between red and black, a voltage corre-
sponding to pressure is output between white and black, and this
voltage is taken in by the microcomputer.
The output voltage is 0.173 V per 0.098 MPa.
* The pressure sensor main body side is to be connected to a con-
nector.
The pin number of the connector is different between the pressure
sensor main body side and the main circuit board side.
Main body side
Vcc Pin 1
Vout Pin 2
GND Pin 3
ON
1 2 3 4 5 6 7 8 9 10
HWE20010
ON
1 2
Main circuit board
side
Pin 3
Pin 2
Pin 1
The figure at left shows that
the switches 1 through 5 are set to
ON and 6 through 10 are set to OFF.
3 4 5 6 7 8 9 10
- 120 -
(Also possible with the display monitor)
Connector
Output voltage (V)
Pressure 0 - 1.7 MPa
Vout 0.5 - 3.5 V
0.173 V / 0.098 MPa
GND (Black)
Vout (White)
Vcc (5 VDC) (Red)
GB