SMC Networks HRS012-A-10 Series Service Manual page 124

HRX-MM-N007
Chapter 3 Alarm Indication and Troubleshooting
Check the connection.
1.
Check the refrigerant circuit pressure sensor (for low pressure) that is connected to the connector
"CN4", pin numbers 12, 23, and 24 of the main board for the check points shown below:
(1) The connector "CN4" is securely connected.
(2) Pin numbers 12, 23, and 24 of the refrigerant circuit pressure sensor (for low pressure) "PS3"
are securely inserted and there is no defective crimping. Check for the correct connection by
lightly pulling the cable.
Fig. 3.3-76 Check connection of the refrigerant circuit pressure sensor (for low pressure)
Check for an input to the pressure sensor in the refrigerant circuit.
2.
Check that the power is supplied to the refrigerant circuit pressure sensor (low pressure).
Check voltage by contacting the probe of the tester directly to the connector external surface with
the "CN4" connector of the main board being inserted.
Contact the positive probe to the pin number 24 and contact the negative probe to the pin number 12
of the "CN4" connector.
<Normal> Pin number 24 - Pin number 12: Voltage should be 5 VDC +/- 1V
3. Check the output of the refrigerant circuit pressure sensor.
Find which has a problem, the refrigerant circuit pressure sensor (for low pressure) or the main
board.
Follow the instructions shown below:
(1) Perform checking with the Thermo-Chiller not operating.
(2) Check voltage by contacting the probe of the tester directly to the connector external surface
with the "CN4" connector of the main board being inserted.
(3) Contact the positive probe to the pin number 23 and contact the negative probe to the pin
number 12 of the "CN4" connector.
(4) Check that the voltage between the pin number 23 and the pin number 12 is in the range shown
below:
<Normal> Between pin numbers 23 and 12: 0.5 to 4.5 VDC +/- 0.2 V
3.3 Troubleshooting
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HRS Series