Tuttnauer 2540 EHS, Technician Manual

Page: 104 / 130

103
Corrections
29.1
Replace the DIG-T2 board.
29.2
Fix the connections.
29.3
Disassemble the valve and check that the plunger is free to move and that the seat is clean and free from debris.
29.4
Replace the ANL-T2 board.
Possible cause check-up and tests
The problem may be a mechanical failure of the
valve, the valve driver located on the ANL-T2 board or the control circuit on the
DIG-T2 board. 29.1
Check TP12. If the voltage is higher than 4V and the valve is open, then the DIG- T2 board is faulty. If the voltage at TP7 is <1VDC and the valve is open, the problem is not the DIG-T2, but some other element of the system.
29.2
Check the connection between the connector JP10 – 8 and the valve for a ground short.
29.3
Remove the cover protecting the terminals of the coil and check the voltage across the coil when the solenoid is connected. If the coil voltage is less than 2V and the valve is open, there is a mechanical problem.
29.4
If the voltage across the coil is higher than 10VDC, then the ANL-T2 board is faulty.
10. TROUBLESHOOTING
(cont.)
10.4
In Process Malfunction
(cont.)
Symptom
29.
Steam valve (93) is always open.