SM 74 popping off impression

[Griznarf]

I have an SM 74 6 P2. When it is put on impression for unit 2 the impression piston goes on then pops off right away. This does not happen all the time. We can go into production and during the run, the impression will come off on 2. When we put the impression on and off manually it works fine, but once in a while it goes on then comes off quickly. We have changed the 2 directional control valves on the impression piston but it still does it. Any ideas?

 

[junker1984]

Have you checked the wires in the plugs going to the coils of the control valves? Throw the unit on impression and wiggle the cables. Suggest you keep your fingers clear of the ram! Seen it many times on 40".

 

[Griznarf]

Yes I have checked the wires wiggled shook. Nothing happened. It still pops off. I have noticed if you touch the icon on the screen to fast or your finger bounces. The piston pops on and off very fast. But cannot figure why it does it when you put the press in production as the console boards do the work.

 

[junker1984]

Reestablished connection at EAK?

 

[junker1984]

Check connections on ribbon cables in LVT box?

 

[Mathew]

How old is the machine? What is the year of contruction?

 

[Waqas_zahid]

The impression throw is a two phase process, first the blanket cylinder gets thrown onto the plate cylinder and in the second phase the blanket cylinder connects to the impression cylinder, can you remove the O.S cover and see if goes off completely for unit 2 during these random events?