RISO RP 3700 DIY service

[mixedfeelings]

Re: RISO RP 3700 DIY service

Well, I double checked the connections (both on the TPH and the boards) and the fuses and everything seems fine. So it I guess it seems that I fried the TPH. It seems strange that there is no test mode to confirm if it is working or not? Also strange that I am not getting in faults or other warnings. Would the machine somehow alert me if I had messed up a PCB?

I suspect this isn't the case - but is it possible that the TPH and the 3105 and the 3700 are the same? I have access to a 3105... If not it seems like this might be my best bet?
Risograph Riso TPH Thermal Print Head for RP3700 RP3790 Used 030 98102 050 | eBay

Thanks again!

[jermyth]

Re: RISO RP 3700 DIY service

The TPH are not the same between 3105 and 3700. You did test the TPH with TM 50. Either a wire/connector is off or the TPH is toast. Id recheck all connectors in the TPH unit and on the boards, reseating them all. Ive missed a connector or two in my time. Good luck.

[mixedfeelings]

Re: RISO RP 3700 DIY service

sigh. that's what i figured.

I reseated all the connectors both on the TPH and on the main and power PCBs. I am still worried that I somehow messed up the PCB, but I am not getting any indication other than no image coming from the TPH.

I ordered the replacement TPH. But, Just to double check, there is the red / white wire set up to the power pcb, and the orange / red wires to the main pcb. are there any easy to over look things that I am missing in there?

Thanks again everyone!

[20gaugeO/U]

Re: RISO RP 3700 DIY service

Is there any way the master roll is installed backwards?

Check the TPH resistance value in TM 288, it should match what is stamped on the TPH? If it is correctly input, then you still could input a much higher or lower resistance value make a maker to see if you get any image at all....purely for troubleshooting. If the TPH is shot you aren't going to hurt anything.

How many copies and masters are on the machine???

[ddude]

Re: RISO RP 3700 DIY service

Might be too late, but check to see if the master roll is installed upside down?

[mixedfeelings]

Re: RISO RP 3700 DIY service

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]

Re: RISO RP 3700 DIY service

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]

Re: RISO RP 3700 DIY service

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]

Re: RISO RP 3700 DIY service

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]

Re: RISO RP 3700 DIY service

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]

Re: RISO RP 3700 DIY service

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]

Re: RISO RP 3700 DIY service

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]

Re: RISO RP 3700 DIY service

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]

Re: RISO RP 3700 DIY service

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]

Re: RISO RP 3700 DIY service

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???