Riso GR3750 won't ink

[Guest]

I bought a Riso GR3750 from a school district, and it came with black, blue and red drums. The black works fine but I can't get red or blue to work - my guess is that they regularly used black and haven't used the other colors for some time. I've taken apart (to the best of my ability) the blue drum, cleaned the outside and inside of the drum, made sure the small holes in the ink feed tube are open, eliminated buildup of ink and reassembled. When I make a master there's no ink on it. I keep getting the "replace ink cartridge" message, even though I'm using a new Riso ink cartridge. I've pushed in the bottom of the cartridge before inserting it to be sure ink is at the top. I made sure the tube from the cartridge to ?? isn't plugged.

Some posts reference a service code (101) to ink the drum, but it wasn't for a GR3750 so I'm hesitant to try it. I started the Riso in test mode and entered 90 to reset (from someone else's post), but still nothing. Will starting in test mode and running 101 ink the drum? Is there a list of test codes somewhere?

I'd like to get the blue drum working and then move on to the red. Anyone know how to revive neglected drums?

Many thanks.

[Iowatech]

Re: Riso GR3750 won't ink

While there is always the chance that the pump is bad, if you cleaned out the drum completely, you may just need to run a bunch of paper through the machine. At machine setup, Riso said to run at least a ream of paper through to get a new inkless drum properly inked up, just make sure that you put a confidential master on the drum first so you don't wreck a lot of paper.
Code 101 works with any Riso of the GR family. GRs had a kind of loud ink pump, so if you run that code, listen for a new sound and if you hear it you'll know that at least the motor on the ink pump is working. (Sort of reminded me of when Captain Kirk's Enterprise got caught in a tractor beam or when my car got temporarily stuck in the snow and I was rocking it out, but that's just me.)

[twigrf]

Re: Riso GR3750 won't ink

Thanks for the ideas.

I tried Code 101 and it did indeed make a noise, but didn't seem to get past making noise and out of test mode, so I had to stop it by cancelling. I made a master and tried to print. Once again, after a few sheets of paper went through it stopped and said to replace the ink cartridge. I pulled the cartridge out and put it back in and tried printing again. There's no ink on the master so the sheets don't feed through and I get the jammed paper message. I reset it, try again, and the same thing happens. Therefore, running a ream of paper through would require resetting it almost 500 times.


I'm going to take it apart again tomorrow and see if I can figure out the pump.


BTW, what is a confidential master?

[Iowatech]

Re: Riso GR3750 won't ink

Apparently they sell Risos to organizations that deal with confidential information, and if a master is left on the drum and some scurvy spy hit the test print button they would get away with the info. So, all the Riso machines I've ever worked on have a "confidential" button (usually on the left hand side of the control panel) which when pressed disposes the master currently on the drum and puts a totally blank one on, even if there isn't any paper in the tray. While the jury is still out on that as a security feature, it works great if you need to store a drum for an extended amount of time, or you need to run a lot of prints through the machine without wrecking the paper.

[Ganderboy]

Re: Riso GR3750 won't ink

I bought a Riso GR3750 from a school district, and it came with black, blue and red drums. The black works fine but I can't get red or blue to work - my guess is that they regularly used black and haven't used the other colors for some time. I've taken apart (to the best of my ability) the blue drum, cleaned the outside and inside of the drum, made sure the small holes in the ink feed tube are open, eliminated buildup of ink and reassembled. When I make a master there's no ink on it. I keep getting the "replace ink cartridge" message, even though I'm using a new Riso ink cartridge. I've pushed in the bottom of the cartridge before inserting it to be sure ink is at the top. I made sure the tube from the cartridge to ?? isn't plugged.

Some posts reference a service code (101) to ink the drum, but it wasn't for a GR3750 so I'm hesitant to try it. I started the Riso in test mode and entered 90 to reset (from someone else's post), but still nothing. Will starting in test mode and running 101 ink the drum? Is there a list of test codes somewhere?

I'd like to get the blue drum working and then move on to the red. Anyone know how to revive neglected drums?

Many thanks.

This is a simple problem with no permanent solution.

Inside the drum where the ink tube goes, there is a metal spigot that goes into the ink tube, the intake tube if you want to call it something. On the end of this tube, on the outside, is a rubber sealing grommet that is glued to a plate. This grommet seals off the end of the ink tube. It goes right into the end of the ink tube when you put a new tube in. What has happened is that the glue has gotten old and the rubber grommet has stayed in the end of the old ink tube. You toss the old tube and the new one goes in easier than normal, but the machine is reading no pressure in the ink (because it's not sealed) and keeps instructing you to change ink tube.

This happened to mine about 3 years ago.

I have to fish the grommet out of the old ink tube each time I change ink and manually insert it over the intake tube, then my new ink will seal.

If you take out an unfinished tube, you can't just reinsert again. You have to fish out the grommet and insert it over the intake tube. If you try to put a tube in with the grommet in the ink tube you will push the grommet right into the ink and you will have loads of fun trying to get it out.

Hope this helps. By the date on this post I bet you don't have the old ink tubes around anymore.

I don't know if this is a part that is available.

good luck.

Ganderboy.

[Exok]

Re: Riso GR3750 won't ink

I can't remember the exact setup of the ink pump on this model but most of the time I've had add ink problems its been due to an air bubble keeping the ink from pumping.

Try this first: pull out the ink cartridge , push in the back end of the cartridge to "prime" it. Make sure you see ink just about to squirt out, reinstall and allow the machine to add ink. It can take the machine up to 10 or 15 tries if the pump hoses are dry.

In worse case I've had to take the pump hoses apart. There is a part of the pump hoses that have a metal housing, inside this housing is a ball bearing and a spring. If this is caked in dry ink you may need to clean it out. This allows ink to flow through it in only one direction. Ink flows from the cartridge to the inking roller inside the drum. If this ball bearing is stuck it wont create the suction needed to allow the ink to flow (stays open instead of closes and opens as ink in pumped).

I hope this helps.
Been a while since I serviced Riso.

[ianmck]

Re: Riso GR3750 won't ink

Had the same problem on two drums. The link arm connecting the pump motor to the pum,p had come off on one of them, the other motor seemed dud. Replaced the missing bolt on to secure the link armm and all fine for that drum.