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12-31-2007, 04:42 AM
I have a GR 3770 that I bought used. The machine came unable to pass paper which I figured out was do to worn down metal on the pressure roller/solenoid assembly. This I was able to fix.

The problem now is the print is off about 1/2 inch in the vertical position(leaves too much margin at the leading edge and cuts off the last part of the trailing print).

So far I've ajusted the timing roller cam and have managed to get the margin to go from about three inches off to the 1/2 inch it is now off(ahh for another 1/2 inch...)

As an experment I traded drums from my other GR 3770 and found that the master making area may be part of the culprit(because of how the troubled machine's drum printed on the other unit and vise versa), but it isn't off by much more than 3/16 inch so this alone doesn't explain all the extra white space.

A note: I reset all the memory settings (test mode 98) and I wonder if I deleted some factory configuration that fixed this?

I wanted some oppinions regarding this before I started trying to reprogram the machine(master making length/paper feed timing). If there were some other mechanical ajustment I'm missing or another fix to this problem, I thought I might save some headaches by asking.

The first week of november I got a crazy idea about trying to start a daily publication with risographs, which I never had seen or used before, and now I have a room with four of the units networked to a computer. I bought all of them used for cheap, and except for this one machine, they work awesome!

I'm not a tech, but I've played one on tv...not really, but I have worked on lots of machines with rollers and such(lots of different photo type machines) so I can use a couple of tools other than the sledgehammer I'd prefer.

P.S. I thought I might ajust the vertical positon from the user interface on top, but it didn't do enough and the print wasn't really "right"

01-02-2008, 02:03 AM
I solved the problem myself! Seems I have a black drum that was/is off. I didn't test enough before, and also the page I was using to test was a little caddywumpus, together it was the amount the margin was off.

I figured all this out by printing different pages on two machines, I also tried flipping the page(this is how I figured out the page was off a wee bit)

Now I'm trying to figure out how to get the GR 3770's printing as well as the two RP units I'm using-I think the RP's may be better able to deal with graphics, any ideas?

If anyone is having trouble with their riso I recomend buying one of the CD manuals sold on ebay, and then downloading a hard copy of the manual for their machine.

There are a bunch of test codes that are really helpful, but I wish Chilton's had a Riso manual!:)

hopefully this helps someone with their problem...

02-06-2008, 04:35 AM
Hi, I have a 3770 and am having problems with the registration between copy of different colours. If I try and run a 2 colour piece the text on the second run always moves around resulting in the text being too close to the other colour. I've noticed that the paper feed tray has a rotary adjustment on it to fine tune the position of the paper in relation to the drum, BUT my entire mechanism seems to float and move. Do your machines exhibit the same 'trait'? I could send a picture if that would help describe the issue. Haven't found too much support anywhere for these beasts. Thanks In Advance Murriso

02-06-2008, 12:15 PM
on the 3770 at the feed table there are several "floating" parts - the stripper pad assembly, the feed wheel assembly and the upper and lower safety switches (the latter are not so much floating as they are just seemingly loose) all that is normal. the dial is an angle adjust for the stripper pad or sheet (pads are small brown thick rubber and sheets are rather thin green rubber, serving the same purpose) the feed problem you've described could be due to paper dust collected on the feed tires (clean with alcohol and swap the front tire for the back tire to increase life expectancy) or a dirty or worn pad/sheet (again clean with alcohol or replace if it shows a deep groove) to adjust the dial use a coin, clockwise will steepen the angle and allow for more contact with the feed tire and counter clockwise is of course the opposite. a good way to get a starting point on the pad adjustment is to set it at the 2 o'clock position on the dial (just to the right of the small notch) and check your feed, you might want to load a blank master before doing a feed check so you dont print on your test paper (open the small cover on the left side of the OP panel and press the "confidential" button then press start) i don't recommend trying to run different paper weights at the same time but you should be ok with an assortment of colors - one thing you might check for - image shrinkage - this can cause your copy to "scrunch" a bit and place your second color in the wrong position, best way to check that is to make a copy that has good coverage and compare the copy to the original. should that prove to be the actual problem you will have to clean the write roller in the master making unit - let me know if thats the case and i will post the proceedure for cleaning it

good luck - hope this helps

02-06-2008, 02:47 PM
Hi Y'all,

One thing that may help you print multi-color documents is to buy a good paper-jogger, if you don't already have one.
These will get your sheets stacked proper for each pass you make and may help solve some of the floating you have.
Another thing I'm learining is that it helps to over-size areas you are trying to over-print, or over-size boxes to create more white space to work with.
I'm not sure if I'm explaining this right, but much of the Riso's registration problems can be solved by over-sizing type boxes or over-sizing your color (colour for those in the commonwealth) box. This is a way of "cheating" those graphics and colors togeather and unless you want to make yourself crazy, I wouldn't try for any exacting registration. If it needs to be super tight and exact, I'd find a good print shop.
Another trick I've read about is operators using a homemade paper feed tray that fits in the slots that hold your paper. This I imagine to help by forcing your paper to stay stacked more exactly than the factory feed post, which seem to be spread out more at the top than they do at the bottom--I know this affects my registration.
If none of this helps I know that you can start messing with the master-making length, but I think this would be the last thing I'd try. The GR series seems more difficult to reprogram than the RP series, but I'm still pretty new to these things so I maybe wrong about this.
The paper-jogger is the one thing I know works great. If I was to start buying equipment again I'd try and find a good air jogger, because I've read they help cut down on the paper dust which can, as Elle noted, cause feeding problems.
Oh and another thing I'm learning is that it helps to let large areas of ink dry before trying to make a second run.
I printing a lot of B&W photos which make for large areas of ink that stick when I make a second pass through the machine. I'm trying to do a newspaper so there is a deadline issue I'm facing with this--I don't want to have to print half the paper the night before just to make the printing easy.
An idea I'm going to try is puting heat lamps at the exit-this should help to put a crust on the ink and maybe help me on my next pass.
I hope this helps you with your problems.

02-06-2008, 09:30 PM
Thanks Dave and Elle, your replies helped. This morning I took out the stripper post assembly and found that the pad had quite a groove in it, so I flipped it 180 and remounted it. I reset the pressure and angle adjustments to the factory defaults and found it jammed immediately. Then I reduced the pressure to the minimum setting and found it ran perfectly. I'm thinking I might have ratched something up though, as once I had screwed the assembly in again, I found the pressure setting to be quite hard to turn, and when it did finally turn it seemed to clack and now the dial seems to have no pressure from the minimum pressure setting until the first setting IE very easy to turn, I seem to remember that this adjustment clicked into each of the pressure zones?? Anyway it ran great for the bond paper I was using. I suppose I should try and order another pad so I have one in reserve. Do either of you know a good place to deal with. We lost our only Riso dealer in our city. I'm in Kamloops, BC. I was thinking of a paper jogger as I've seen them in print shops. I use my Riso in my real estate practice for flyers etc and I'm not to sure where I could pickup a jogger. Any ideas. How much? etc. Thanks again, great responses and fast! Murriso -1/2 Murray and Riso ;-)

11-19-2008, 03:23 AM
I've been repairing my own GR3770 lately, and have noticed and repaired one thing that made a major difference. There are two sensors at the paper feed. One that lets the machine know there is an incoming, and another that senses the edge at the guide and timing roller. When these are properly cleaned, and the lower guide plate is installed properly, lighter weight paper will bunch up against the thin paper guide rollers on the pickup roller shaft. Before I adjusted the lower guide plate, the timing roller wasn't evenly visible from the paper feed side. Paper was loading skewed. Also, the disty sensors allowed for late or early feeds. This caused the paper to be inches off from center.

I'm only about 1/2 to 1" off from where I want my prints to be, but all I should need is some time, and I will get it back to true center. The guide plate and those sensors are very important to set right.

Any help for setting the paper timing right would be greatly appreciated. Seeing as I have ot done that before, I'm going to spend a lot of time trying to figure out the next step.

11-19-2008, 03:49 AM
I don't know if you've done a google search for GR 3770 repairs but L/H (this is the guy's name-LH) he is quite good at helping figure out problems, he is a duplicator repairman by trade and has helped me before. He has a website up that deals with just duplicators and Riso's especially.

Of course I don't have the name of the website handy at the moment-My computer crashed a while back and I haven't needed any duplicator help so I haven't added the website to my bookmarks yet.

Hopefully I helped a bit-probably would be better to have found the web address for you, but I bet it isn't that hard to find. If it is, let me know and I'll try to find it myself.

That said, you are on the right track cleaning the sensors and getting all those rollers spaced right. My machine was used when I got it and the feed area was all screwed-up, the rollers were tighter on one side, dirty ect.

But one of the biggest things that I've found is that the drum also makes a difference in how even the printing area stays. I have three black drums, all 11x17, and one is shot-it won't ever print even, one is ok, and the one I use the most is awesome! This may help keep you from pulling-out too much hair trying to fix your machine when it is the drum that can be off.

I wish you the best,


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