Tuttnauer 2540 EHS, Technician Manual

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100
Corrections
25.1
Replace the DIG-T2 board.
25.2
Fix the connections.
25.3
Disassemble the valve and check that the plunger is free to move and that the seat is clean and free from debris.
25.4
Replace the coil.
Possible cause check-up and tests
The problem may be caused by the mechanical
part of the valve or the driver located on the ANL-T2 board or the control circuit on the DIG-T2 board.
25.1
Check TP10. If the voltage is constantly <1VDC, while the valve is supposed to be open, then the problem is on DIG-T2 board.
25.2
Check the connection between connector JP10 - 6 and the valve for an open circuit.
25.3
Check the coil input voltage with the solenoid connected to the valve. If the voltage is higher than 10VDC and the valve does not open, then the solenoid or the mechanical part of the valve are faulty.
25.4
Take an ohm reading across the solenoid coil, a 10W coil is 14-15 ohms and a 12W coil is 9-10 ohms. An incorrect ohm reading means the coil is faulty. Check from the coil terminal to the ground terminal, any reading other than 0VDC means the coil is faulty.
10. TROUBLESHOOTING
(cont.)
10.4
In Process Malfunction
(cont.)
Symptom
25.
Water valve (15) to vacuum pump is always closed.