Riso FR 3950 UI - Print Quality Issues

[Safety_Man]

Hi everyone,

I have two issues regarding print quality that I was hoping you could help me diagnose and hopefully remedy.

First off, my prints have a series of very fine vertical lines running across them. Is this caused by the thermal print head? I opened up the machine and there was some crud on there so I gave it a wipe with a cloth. The crud was gone, but the problem still persists. Any ideas? Here's an example of what I'm talking about.

Secondly, I'm experiencing fading and patches on the sides of my prints for both red and blue inks. Could this be cause by a clogged screen on the drums? I soaked a paper towel in degreaser and let it sit on the drum for 15 minutes, gave it a good scrub and it improved a bit. Should I take the drum apart to clean it? Here are two examples of this issue.


Thanks in advance for your help.

[Iowatech]

Re: Riso FR 3950 UI - Print Quality Issues

The first picture does indicate a thermal head failure.
About the light area, that kind of looks like ink depletion due to insufficient prints being run per master. If you put a confidential master on the drum and run fifty or so prints, does it get any better? Make sure to use a confidential master for this so you don't wreck a bunch of print paper while testing this out.

[Safety_Man]

Re: Riso FR 3950 UI - Print Quality Issues

The first picture does indicate a thermal head failure.
About the light area, that kind of looks like ink depletion due to insufficient prints being run per master. If you put a confidential master on the drum and run fifty or so prints, does it get any better? Make sure to use a confidential master for this so you don't wreck a bunch of print paper while testing this out.

Iowatech to the rescue again. Thanks for replying.

Now, when you say failure... you're saying its time to find a replacement?

I'll try the confidential master on there, but I'm not really sure how that works. Why will the confidential master help more?

[Safety_Man]

Re: Riso FR 3950 UI - Print Quality Issues

The first picture does indicate a thermal head failure.
About the light area, that kind of looks like ink depletion due to insufficient prints being run per master. If you put a confidential master on the drum and run fifty or so prints, does it get any better? Make sure to use a confidential master for this so you don't wreck a bunch of print paper while testing this out.

I ran about 200 copies with a confidential master. It definitely helped some of the fading on the sides, but there are still some patches left.

[Iowatech]

Re: Riso FR 3950 UI - Print Quality Issues

It looks like the thermal head does need to be replaced. However you might want to check the connections on the thermal head and the main board first.
Thanks for the update on the light areas. That kind of makes it sound like the pressure roller is worn out. Or, it has a lot of ink build up that prevents the ends from pressing on the drum enough to let ink through, but that's a really unlikely longshot. I scraped ink buildup off pressure rollers and that rarely made a difference.
One thing, the thermal head was the most expensive part I've ever ordered for Riso equipment (usually around one Kbuck direct from Riso if I remember correctly). I'm not sure that's still the case for the FRs, but be aware getting a new thermal head could be rather costly.

[Safety_Man]

Re: Riso FR 3950 UI - Print Quality Issues

It looks like the thermal head does need to be replaced. However you might want to check the connections on the thermal head and the main board first.
Thanks for the update on the light areas. That kind of makes it sound like the pressure roller is worn out. Or, it has a lot of ink build up that prevents the ends from pressing on the drum enough to let ink through, but that's a really unlikely longshot. I scraped ink buildup off pressure rollers and that rarely made a difference.
One thing, the thermal head was the most expensive part I've ever ordered for Riso equipment (usually around one Kbuck direct from Riso if I remember correctly). I'm not sure that's still the case for the FRs, but be aware getting a new thermal head could be rather costly.

The vertical lines are subtle enough right now, that they don't bug me too much. I got this Riso for $35 and according to the print counter its had a long history, so I don't think I'll be going in on a new TPH for it unless I stumble upon another one for cheap, which I'm guessing is pretty unlikely given this machine's age.

A friend of mine mentioned adjusting the voltage on the TPH to potentially correct the vertical line issues. I found a thread on this board that went into some more detail. Have you ever heard of this? What's the probability of it correcting the issue? If it's too risky and there's a high percentage of breaking the TPH completely, I think I'd rather just stick with the thin vertical lines. I'm not doing anything too fancy with the RISO, just wanted a way to cheaply produce my comics.

I'll take a look at the pressure roller for ink buildup. Are there any indicators (other than the print quality) that would signal the pressure roller being worn out. Any recommendations on suppliers for a new one?

Thanks again for all of your help, Iowatech.

[Iowatech]

Re: Riso FR 3950 UI - Print Quality Issues

The vertical lines are subtle enough right now, that they don't bug me too much. I got this Riso for $35 and according to the print counter its had a long history, so I don't think I'll be going in on a new TPH for it unless I stumble upon another one for cheap, which I'm guessing is pretty unlikely given this machine's age.

A friend of mine mentioned adjusting the voltage on the TPH to potentially correct the vertical line issues. I found a thread on this board that went into some more detail. Have you ever heard of this? What's the probability of it correcting the issue? If it's too risky and there's a high percentage of breaking the TPH completely, I think I'd rather just stick with the thin vertical lines. I'm not doing anything too fancy with the RISO, just wanted a way to cheaply produce my comics.

I'll take a look at the pressure roller for ink buildup. Are there any indicators (other than the print quality) that would signal the pressure roller being worn out. Any recommendations on suppliers for a new one?

Thanks again for all of your help, Iowatech.

Increasing the voltage would lead to premature failure of the print head, at least that's what the training said. So I wouldn't try that until the lines are an actual problem.

If you have a decent straight edge which is long enough and a bright flashlight, see if any light can get between the straight edge and the pressure roller. You could also take the pressure roller out of the machine and place it on a flat surface and see if light can get between the the roller and the surface. If light gets through the roller is likely the problem.

If you take the roller out of the machine, be careful, the the edge of the guide on the right hand side of the roller can be kind of sharp.

I've only used Riso pressure rollers, so I have no sure bets as where to get a new one for that machine. I have heard rumors that Precision Roller might have something that would work, but use that at your own peril.

[Safety_Man]

Re: Riso FR 3950 UI - Print Quality Issues

I'm very happy to report that I've made some really great progress on the splotchy print quality.

I took a look at the pressure roller with a straightedge and it didn't appear to be warped anywhere.

Looking at the splotches on the edge of my prints, there wasn't any sort of pattern that would indicate the issue was being caused by specific spots on the pressure roller, so I was thinking maybe the brush I was using to scrub the drum screens was too big. I picked up a couple of toothbrushes to try out.

Seemed to do the trick! I (tooth)brushed the screens for about 15 minutes each using citrus degreaser, focusing on the problem areas and it cleared up almost completely.

Thank you Iowatech for all of your help! I really appreciate it. I'm very excited to have finally resolved this issue.

I think I can live with the TPH issue for now. If it gets a lot worse in the future, I might fiddle with the voltage, but for now, it's working well enough... knock on wood.