Press Won't Stay on Impression

[Pressmanscooter]

1992 Heidelberg CD 102. I have a weird problem that I can't diagnose. When starting the press on production, here's what happens:
Water forms drop
Swing gripper takes sheet out of the headstop, feeder is running
1st unit goes on impression (not printing in 1st unit)
Ink forms drop in 2nd unit
2nd unit goes in impression
==> All at once 1st and 2nd unit go off impression, ink forms go off, dampening remains on in all preselected units, press slows to 3000IMP/H, 4 blank sheets land in delivery, press stops.

This cycle (Production to press shut off) can repeat itself 3 times or 15 times. This my happen once a day, twice a day or once a week.
There are no error's or warnings being displayed in the fault screen while any of this is happening. I can't find any connection to why it does it, or when it does it. I'm just stuck in this cycle.
Any suggestions entertained.

Thanks
Scott

 

[LSW]

I've seen this happen if pneumatic pressure supply drops too low but only on later presses and always accompanied by an alarm. Do you have a big air leak on the 2nd unit impression or low supply?
It's also the same behaviour as pressing the "halt" button so perhaps a fault with the one on the 2nd unit and the vibration of it going on impression is triggering it?
Hope you get it diagnosed.

 

[mikwil2000]

I had a similar problem onetime like that but mine was the sending unit switch located on oper side. 1st unit I just move it closer to the cam..
Not to sure if this is your problem though, any brain storm is a good one in printing. Lsw seems like he is in the ball park.

 

[Pressmanscooter]

Thanks LSW. I actually have the air pressure sensor jumped out. That was the remedy to another problem a few years ago. But you are right, it does behave like that. I wished there was a fault, so i'd at least have a directions to go in

 

[Pressmanscooter]

Oh and thank you too, milkwil2000. You both responded to my thread even thought it was clearly in the wrong forum. I actually posted it twice thinking I had accidentally posted it incorrectly the first time. Turns out "THE ADMINISTRATOR" has moved it from the sheetfed/web forum both times. According to him or her, "If it's a Heidelberg press it should be in the Heidelberg forum." I guess not everyone around here is that bright.