Replace Broken Gear in the Master Making Unit (on 2-drum machines)
In this tutorial, you'll be guided through the necessary steps to replace a broken gear powered by the Thermal Pressure Motor (error message on screen: T19-208 or T19-XXX) — the process shown here should work on all 2-drum machines but was performed on a MZ1070.
This gear wears out quite quickly, so it's very unusual that this happens. You can get replacement gears easily on sites like AliExpress for little money (search for the part #612-10010) — make sure to have it at hand before you open everything up!
Estimated time it takes: 1,5h
Level of skill required: Basic Riso Operator who's held a screwdriver in their hands before
Tools needed: Screwdriver, Pliers, grease
Before you start, make sure the Riso is unplugged from power! Then grab a sheet of paper and draw some circles on it with numbers next to them. In these circles you can put the screws you remove from the Riso. With Post-its, mark the respective numbers on the parts the screws belong to.
Good luck!
Steps
There are 5 screws in total.
Unscrew and carefully remove the cover (might be hooked in a bit on the left side)
Two screws.
Carefully pull the plastic cover towards you and set aside.
Carefully remove the two cables (marked in Pink) from their sockets: Gently wiggle and pull towards you, the bigger connector has two hooks that keep it in place, carefully bend them aside. Then pull out the cable clamp (top pink circle).
Unscrew the two screws (green circles).
Carefully pull the Master Removal Unit towards you (it's quite heavy).
Open the cover of the Master Making Unit (MMU), then push the MMU in, quasi "towards" the other side (where you just removed the Master Removal Unit). It might not move forward inside the machine, hence check the next step
The hook stops the MMU from going inside the machine when changing the master. Push it to advance the MMU inside the machine.
Then go to the paper feed side of the machine.
The MMU (pink rectangle) is now visible from the paper feed side. Remove the two screws (green circles) — you will need to hold back the MMU so it doesn't slide back to the other side. Then return to the other side of the machine and carefully pull the MMU back out.
Unscrew two screws and set the Bottom Cover aside.
!!Make sure NOT to touch the TPH stripe (yellow/orange color)!!
Take off the Black plastic snap ring, but watch out for the spring below, it will jump off! Take off the spring as well.
Pull up the TPH (remember not to touch the orange stripe of the TPH!) and try to hold back the lower bronze bearing metal. Before you can fully remove the TPH, you need to unscrew the earthing (see photo in the next step).
Unscrew the screw that holds the earthing of the TPH (green circle) and watch out that the screw doesn't fall inside the MMU.
Two more screws (green) circles and together with the screws from Step #7, the cover will come off.
If the gear’s intact, you might have a different problem, sorry!
The fulcrum shaft is the black horizontal shaft. We need to remove it to get to the broken gear.
Watch out, there's a good deal of tension on the springs. Remove them from the top first and then untangle them and take them out.
Be careful, the e-rings are very tight and tend to jump off and are never found again. You can do it with special pliers (not the ones we used) or with a screwdriver (see next step).
Turn the white piece on the right side until you see the screw, then unscrew it.
Then unscrew the middle screw (left green circle), there might be a rest of plastic from the broken gear underneath it.
Don't put in the screw, first put the shaft back in place. Now reassemble the small shaft.
That's it, now grease the gear and reassemble everthing!