mov impression problem

guys need help with impression problem.

sometimes 2 to 4 unit will not engage. only 1st unit will engage impression.

how can i fix this?

also when the machine stops, last sheet doesnt have the last 2 unit color.

tia

 

Hello alx, You didn't mention the model year of your MO, but I'll assume it's pre-1990 and not CPTronic. Your problem likely stems from worn roller switch components. Look at the switches that ride a cam on the impression cylinder journal. These are under the operator side covers.

 

I had the exact same problem and technician checked and I confirm what junker says about the roller switch

 

yes sir junker, it is without cp tronics. please see 2 images..

1st image i found a hole in the plunger. it got stuck up.

after replacing the switch with a new one, impression worked for awhile. then again becomes intermitent

 

can i put epoxy to fill the hole?

 

2nd image.


from what i understand the two arrows pointing to the 2 screws is normally connected.

when plunger is down it should release the contact. unfortunately mine is always on contact whether plunger is up or down. is this normal?

picture reference is the first unit.

 

Epoxy is a good fix. I have done that often. Regarding the contact points, they must make/break as the cam turns. Maybe you were looking at points while on high side of cam? Also, you must check all roller switches at printing units #1 and #2 in order to get proper sequencing of relays in cabinet. I should have mentioned you must also mark position of switches with a scribe.

 

Dear Sir:
Mr Colleague Junker has reason.
Please test the limit switchs in section Printing # 2: #b201 +b261 +b262
2) Section printing # 3: b 267+b268+b269+
3) Section printing #4: b270+b271+b273
All this are called Limit switch Cam for 1+2+3+4 printing units.
Please use the schematic diagrams, and location components.
Test the continuity contacts, for dirty oil, oxide, or burn, or broken. Clean or repair, and tight very well the Loose wires in the L.switchs