RISO RP 3700 DIY service

[mixedfeelings]

20gaugeO/U, thank you! that was it!!

It definitely was the TPH resistance value. When I reset the machine to default settings, it also reset the resistance value to 1200. I just changed it to the number printed on the TPH and I am back in action.

Are there other things that I should be looking for after resetting to factory default settings?

A new issue now that it is printing again is that the image is moved towards the feed side of the page - starting at 1/8" from the top.

Regarding the The 1/16th master skew issue (which is still around) - could the parallelism of the pressure roller be pulling it? I noticed that is adjustable.

thanks again everyone!

[20gaugeO/U]

I'd still start with a new impression roller before messing with parallelism. If it is bulging a little more on one end it will pull sooner. When real bad it will wrinkle the masters.

Also sounds like you could adjust the write roller start position for the image up the page.

[mixedfeelings]

I spent a couple of days tinkering with everything, including replacing the pressure roller, retiming the machine (to center the print position) and getting everything worked out. On first print, i have everything centered and the skew down to about 1mm (new pressure roller / moved guide roller parallelism all the way to the right). However, as I print, the skew increases - so the master is getting pulled in a clockwise direction as more impressions are made. I have been compensating by making a new master every couple of hundred impressions but it seems like there has to be a better / more permanent solution to this. Any ideas?

Also, do RP 3105s and RP3700/3790's have the same mother boards / circuits and such or are they just totally different machines - trying to determine how much I can use my 3105 as a parts machine or if I should just get rid of it.

Thanks again for the pressure roller advice / other advice! it's definitely gotten me close to where I want to be.

[20gaugeO/U]

To much pressure from the imp roller will cause the master to slip from under the clamp plate (usually after thousands, not hundreds though). Since you say it does it on multiple drums that's where I'd go next.

Are OEM ink and masters being used?

As for 3105 vs 3700 vs 3790 parts...most mechanical parts should be the same...boards probably not compatible but each would have to looked up for part number before blowing something up.

[c_merengo]

You mentioned in your original post that a parts source in Europe would be useful.

Here's one in the Netherlands:
Our Stock

Also, these folks have told me in the past they can get hold of parts if you have parts numbers:
4TOPS Riso Supplies, Riso Ink, Inks, Riso Masters, Master Rolls, Roll, Riso Consumables , Riso Coloured Ink, Risograph, Great Prices

I don't have any direct experience of ordering parts from either of them, so I don't know if they can be recommended, but thought you might find this useful anyway...

Hope it helps!

[mixedfeelings]

I may have had a breakthrough observation with my skew problem - but it comes as result of another problem - it never ends! suddenly last night my masters stopped feeding and would get bunched up - I carefully ran a piece of card stock through to make sure there were no obstructions. I ran TM 253 (write & load pulse motors) and, while the rollers were rolling the master wasn't moving. I found I could only get the master to feed when manually lifting the right master tension collar (the one above the colored flange). When i lifted just the left tension collar, above the white flange, there was no change. This difference in tension here seems like it jives with my perpetual clockwise skew - do these collars wear out? it seems like pressure is pretty locked into place with that plate.

I might flip them and see what that does - but the fact that it suddenly stopped feeding is worrisome. is that a sign of some kind of a failure?

Thanks in advance!

[jermyth]

Im not sure I understand which roller youre pushing on, there are three black rollers in the master making unit. 1st is the tension roller, right after the master roll, this has a torque limiter on it that might be causing your problem. 2nd is the write roller & 3rd is the load roller, they are both motor driven by seperate motors. I dont see any bushings that could be causing this problem, at least not with a part number in the parts manual.
Picture of which roller, maybe?

[mixedfeelings]

The actual part that I am lifting (not pushing on, reducing the pressure) is the master tension collar - the little white brake that applies tension to the large plastic flanges on either side of the master roll. When I lift the right tension collar / brake i can get the master to move.

It seems possible that write roller is no longer gripping the master properly - i have head mixed reports about whether or not to try to clean this or not / possibilities of it warping images after being cleaned?

[jermyth]

Id try cleaning all three rollers with a scotch bright, lightly scrubing off any master buildup.
But you might need new master roll flanges.

[20gaugeO/U]

If the brake is worn through it can cause hesitation when making the master. Can the front and rear be swapped so they are rubbing in different places? Otherwise just take out, set aside and try w/o. It may cause a wrinkle on the loaded master but that's troubleshooting. I don't have a machine to look at.

As for the write roller you can clean it. It's rubber and will become "dog boned" over time and use (RP released 2001). Belt cleaner works for me at shocking it back. Others like water, simple green, or alcohol just make sure it's dry before burning a new master.

Didn't I say these machines were over complicated???