Mitsubishi Electric EHGT17D-YM9ED Service Manual page 59

Check method of DC brine pump (brine pump/Controller circuit board)
Notes
1
· High voltage is applied to the connector (CNF1) for the brine pump. Pay attention to the service.
· Do not pull out the connector (CNF1) for the motor with the power supply on.
(It causes trouble of the controller circuit board and brine pump.)
Self check
Symptom: The brine pump cannot rotate.
2
Fuse check
Check the fuse (F5) on controller circuit board
Did the fuse blow?
No
Wiring contact check
Contact of brine pump connector (CNF1).
Is there contact failure?
No
Brine pump check (CNF1)
Is the resistance abnormal?
No
Power supply check (Remove the connector (CNF1))
Measure the voltage in the controller circuit board
TEST POINT 1 : VDC (between 1 (+) and 4 (−) of the brine pump connector): VDC 280–380 V DC
TEST POINT 2 : VCC (between 5 (+) and 4 (−) of the brine pump connector): VCC 15 V DC
Is the voltage normal?
No
Replace controller circuit board
Check the operation.
Fail
Replace the brine pump.
HOW TO CHECK THE COMPONENTS
<HIGH PRESSURE SENSOR>
Vout (V)
4.5
2.5
0.5
OCH722A
Yes
Replace controller board (C.B) and brine pump (MBP1).
EHGT17D-YM9ED
UNIT
Brine pump
Measuring points
pin1–pin4
pin5–pin4
pin6–pin4
pin7–pin4
Yes
Replace the brine pump.
Yes
OK
END
PRESSURE
2.5 5
(MPaG)
(PSI)
BH56N077
Resistance
1.6 MΩ
37 kΩ
Replace the brine pump.
Yes
Check the operation of brine pump.
Fail
Replace the controller circuit board
CONTROLLER CIRCUIT BOARD
5 V DC
3
WHT
2
BLU
Vout
1
BLK
63HS
3-1 : 5 V (DC)
2-1 : Output Vout (DC)
59
OK
END
MICRO
PROCESSOR
GND