Hitachi UX Twin Nozzle Service Manual page 206

(2) Fault locating method for the control system/circulation system
(a) When the pump motor and all the solenoid valves are not operated, the multi-power supply
(24 V system) is abnormal.
(b) If the electrical parts (pump motor, solenoid valves, and pressure sensor) are not operated, i,e.,
any case other than above, make the following checks first. When the criterion is satisfied, the
power supply, EZJ126 board, wiring, or connector is abnormal.
Part
Pump motor
Solenoid valve
Pressure sensor
Check method
(1) Operate the pump on
the "Solenoid
Valve/Pump Test"
screen.
(2) Measure the
voltage at pin
No.5 (wire: red)
(1) Exchange the
solenoid valve and/or
the connector with
another normal
solenoid valve and/or
connector.
(2) Set the solenoid
value to "Open" on
the "Solenoid
Valve/Pump Test"
screen and check the
sound.
Measure the voltage at
pin No.1
(wire: yellow)
Measure the voltage at
pin No.3 (wire: blue)
when the ink is jetting.
4-72
Criterion
20 V DC or more
An operation sound shall
be produced.
DC12V±10%
Pressure Output
[MPa] voltage [V]
0.1 1.5 to 1.6
0.2 2.1 to 2.2
0.3 2.7 to 2.8