RZ990 feed / timing (?) issues

[mixedfeelings]

Hello all,

I have a new-to-me RZ990 (just under 3million impressions) that is having some serious feed issues. I have been trying to solve this issue for weeks and I am finally at my wit's end.

When making a master, the paper jams (leaving the drum to imprint on the pressure roller), stopping sometimes at the guide/timing roller, sometimes at pressure roller, and sometimes (rarely) it will pass through all the way. Always with a J8 error.

In addition, when it does feed, the prints jump wildly from print to print. Here is an image of two sheets that were printed in sequence overlaid with light shown through to see how much the position is jumping vertically:

rz990_jump.jpg

Things I've tried to resolve this:

• All of the obvious feed dial settings
• Adjust the parallelism of the guide/timing rollers
• Remove and clean the 2nd feed paper sensor (thinking maybe a blockage there would stop the paper)
• Remove / clean / return existing feed clutch
• Completely replace the feed clutch with a brand new one

None of that worked, and eventually, I couldn't feed at all. At that point, I decided that the machine must be out of time so I started taking it apart. When I got to the main gear, I discovered that machine's timing points were indeed still in the right place, but the screws holding the main gear in place had come loose. All three screws were loose, and one had even completely worked its way out, like so:

rz990_timing_notches.jpg
(you can see the timing notches in the circled area)

I tightened the screws and thought that surely I had solved my problem - but, alas, it remains. It is feeding again, but with the same inconsistency as before (the above photo illustrating the jump was taken last night, well after the screws were retightened)

All of these issues still have me thinking that the timing might be off, but all of the timing notches/timing holes seem to be in the proper position, and I know it's not the clutch because both the old and new ones are behaving in the same way.

Any ideas of what this could be?

Thanks in advance!

[mixedfeelings]

I am still fighting with this machine. After a deeper dive, I found that some of the teeth on the print positioning intermediate gear were broken. However, even after replacing it I am still getting the spotty print position and regular paper jams (J8 errors when in normal print mode, A7 when in tech mode) described above. Somewhere between 3 and 10 sheets, it stops feeding the sheet about half-way. If I am really lucky I can get about 15 prints out before it misfeeds and the vertical print position drifts - even with the new gear (though less, for sure).

I've made sure to get all of the gears, timing holes, additional adjustments lined up on the main gear assembly, inner and outer vertical positioning gears on paper feed assembly, separation pump, print positioning intermediate gear, idler gear, and g-lever.

Every time I put the drum into position B the main gear assembly and outer vertical positioning gear both go back to where it should, but the inner vertical positioning gear does not. I marked the timing notches on the two sides with a sharpie so it would be more noticeable and counted the number of times I had to run the test mode for position B (machine) for the notches to line back up. It took 5 times, and it always eventually meets up. here is a video of the process: www.instagram.com/p/BhGoDHJgoTc/

I know that this gear has a large diameter and number of teeth, so it's obvious that it could have a different timeline than the others- but should the timing holes line up every time instead of every fifth time? is the 8mm jig hole in the paper feed assembly just for first time lining up?

I feel like I have done everything I can think of with this machine, but is there still something obvious that I could be missing?

[Iowatech]

Um, based on the second picture in your first post I think that machine is way out of time.But I haven't worked on the new equipment like your machine in years so I might be full of crap.
Still, based on that picture, there should be a mark on the left hand gear that is aligned in some way with the two marks on the right hand gear,
Sorry for the waste of time.

[mixedfeelings]

Hi, Iowa - thanks for the reply. Definitely not a waste of time, I really appreciate it!

In that second picture, they are actually aligned - the one mark on the left gear is exactly in the center of the two marks on the right gear (unless I am miss-seeing it). That's how it should be, right?

But it doesn't always stop in that position, i found - I have to cycle through "position B" 5 times to get them to line up again. Should they Always stop in exactly that position?

[Iowatech]

Hi, Iowa - thanks for the reply. Definitely not a waste of time, I really appreciate it!

In that second picture, they are actually aligned - the one mark on the left gear is exactly in the center of the two marks on the right gear (unless I am miss-seeing it). That's how it should be, right?

But it doesn't always stop in that position, i found - I have to cycle through "position B" 5 times to get them to line up again. Should they Always stop in exactly that position?

Rats, sorry, I missed the mark.
Still, everything should stop in the same position every time. So based on older machines it sounds a little like the drum drive coupling is worn, If you have another drum you might see if it works better. It could be a sensor in the drum cavity too.
Something that is less likely is that there is a minor memory corruption. If service code 110 still relates to jam clearage you might try that. Or, for every single Riso line that I've worked on except the RNs, holding down the "Reset" key on the right hand side of the control panel while turning the machine on, and continuing to hold the key down until the initializing motor sounds stop (roughly five to ten seconds) used to do practically the same thing.

[jermyth]

There is also a one-way gear on the timing roller, and if it's slipping that can get shifting image position as while as jamming. If you got the manual see chapter 6 second paper feed. Also has all three marks for timing. And I do believe it takes 3 or 5 revolutions to have all the timing marks line up.

Good luck.

[mixedfeelings]

Oh, this is a good lead! I know that replacing that gear is on the preventative maintenance schedule, and my machine is pushing about 3Million copies... I should probably start replacing a lot of the second feed mechanism.

Thanks!!