Floating print position

**smallprintds** · 05-02-2012

I've just finished tuning-up my GR 3770. I've learned a lot in the process, but can anyone tell me why the print floats horizontally, sometimes as much as an eighth inch? It seems to feed weird... or is it something to do with the print roller?

Any suggestions?

**nancy85830** · 05-02-2012

hi, i'm not clear about your problem. Could you describe it more detailly, maybe there is some problem of your presuure roller.

**smallprintds** · 05-02-2012

My print seems to wander a bit side to side (as opposed to up and down). The first three to five prints the edges are perfect, then the print drifts so that the leading edge has more white border, then after a few it will drift back to where it was. This will continue for as many copies as I make. Not such a pain on my black and white pages, but if I do a color plate, the drifting of the print becomes a bit troublesome. I can use the print position keys to keep it in check, but this is kinda a pain in the hindquarters

The machine in question has always kind of done this... I sort of thought it might just be how these things work. But I've been using my RP 3500 a bunch recently and it prints like a charm. A very slight drift of the print but nothing compared to the GR 3770.

After what I've been through this week to make the GR 3770 work, I'm just happy it's printing again. If you are really, really bored, you can search thru this site and see where I had a problem with the thing printing a few months ago and this is the sort of problem I was having again. I have recently moved the office, which was a trip to print drama city. First, my tired old windows 98 computer that drives the Risos died. I got that fixed, put out a perfect issue of my publication and then the GR 3770 died. It had a problem where it never removed the old masters... I was doing it by hand until last Sunday. That's when it tried to remove a master itself and all hell broke loose.

The big problem there seems to be that I'd let ink build-up on the master removal rollers and in the cold of that morning, the old ink gummed up everything so much that it toasted the motor that drives the master removal rollers. Fun! I have a back-up GR 3770 that I haven't been able to completely fix (this is a long story... the short version is that I had a "T" error come-up and I thought I should tear the machine apart to fix the error code (I can't remember the exact one, it was so long ago) I found-out after the machine was apart I could have hit 'reset' and the code would have cleared (dumb, dumb, dumb) and when I put the thing together again, I had print position issues on this machine too) I took the master removal stuff out of the parts machine and fixed the 'drifter' GR machines master removal problem. Unfortunately, when the master removal machinery got stuck it messed-up the printing. Maybe the beast's drive belt skipped a few notches? I'm not sure, but I had some print position problems and I spent a few hours dialing the print position back into acceptable range.

Doing all that I learned quite a bit about how the machine works... I'm pretty sure I can even fix the other GR now. But I still haven't been able to figure-out the issue with the drifting print.

I'm not sure if this information helps or just confuses the whole shebang. Regardless, I thank you for your reply.

Also maybe you or someone else knows where I can buy the little geared motor that runs the master removal system? It's a DC geared motor, with these numbers: 57A-AM-18-A268, 24volt DC, number 90402 and the gears are built onto the motor. What happened, is the gears inside the lil' thing stripped-out. What a noise that was!

Sorry for the long weird stories... just kinda how I tell things.

**smallprintds** · 05-02-2012

What an education in Riso I've been getting lately...

Today I went to see if I could make the other GR 3770 run right. The first print off the drum reminded me what the problem with it really is: the last 1/2 inch of the print fades like the print roller is un-even, BUT (notice the big but?) the rest of the print, from edge to edge, looks great.

In the process of trying to adjust things so this doesn't happen I learned quite a bit about ways to adjust where the machine prints from edge to edge... I even figured out how to adjust the print roller a bit, but I wasn't able to make any adjustments that would change how the print just sort of fades out. I thought maybe it was the drum but on the other machine, using the same drum, this doesn't happen, the drum prints great.

Regardless of anything, I'm still ahead because of how much I just learned. At least I have that, even if I don't have machines that work perfect

**nancy85830** · 05-02-2012

Hi, thanks for your long story

, it's very interesting. I really think that you could be a technician of GR3770 after finished the story.

. Anyhow i uploaded a photo of the parts that would be what you are looking for. Is it that what you looking for ?

**smallprintds** · 05-02-2012

Nope. It's one of those motors that has an attached gearbox and drives a belt. It's under the master disposal box... looks a lot like the motor that drives the inking system in the machine.

Thanks for the reply and the nice words.

**Kopyrtek** · 05-02-2012

The disposal motor will be hard to find. Easier to buy used GR on Ebay....keep it for parts only. The drifting you have is b/c the timing and giude rollers are not parallel. You can test by running two 4.25X11...one on each side of the paper feed tray. Feed up into the machine by pressing the small black button on the board in the back. This will rotate the main motor in slow speed. If pushed far enough in it will pull the paper in. Stop when the paper is halfway in and see if you have EQUAL pressure on both sides. If not, then turn the eccentric cam on the upper roller( located inside the front door) until you have about the same pressure on both sides. Only good if the timing and guide roller are in good shape.

**smallprintds** · 05-02-2012

Thanks! That sounds like a great test for me to try. And I figured one of those motors was going to be a pain to find. I figured I'd use the thing for parts, but on the other hand, trying to make it run has taught me a bunch.

**nancy85830** · 05-03-2012

hi, i attached a photo of the parts frame, could you point out which one you need. We have a used master disposal motors, but not sure whether it is what you are looking for. And the original part no. is 017-65003.