Need Help Blemishes in Prints

[McDonald Signs]

I have a Roland SC540 and am having "Blemishes" or bad spots in my prints.
Just had the Encoder strip and the Encoder reader changed out by a technician and the printer ran fine
for about 2 weeks. Also the technician changed out the dampers and a print head and "tuned up" the printer
replacing whatever it needed.
These blemishes are in a straight line in 2 places on each print no matter what brand of vinyl
I put in the printer. The blemishes are in the exact same place no matter what brand of vinyl I print on.
So it's not media contamination.
My nozzle test print is good.

Attached are photos.....

Any help would be appreciated.

 

[Solventinkjet]

Looks like the media might be getting contaminated by a pinch roller maybe? Maybe the tech greased the rail and some of it got on the roller.

 

[McDonald Signs]

No I checked that, NO rollers touching the vinyl in each of those 2 places.

 

[Solventinkjet]

That's a weird one. It looks like grease because of the way it repels the ink. It doesn't seem electrical or head related either. You have a few missing nozzles but that wouldn't cause this to happen. It doesn't look like a standard encoder issue but since it was changed recently, I would take a look at it especially in the areas where the issue is. If you see ink splatter or even grease on the encoder, it can cause weird issues and usually they will show up in the exact same place in that case just like yours. It's worth a shot to take a look and clean it if it needs it. Maybe Joe House or Jim Hancock haven't left for vacation yet and can chime in.

 

[McDonald Signs]

I did clean the encoder strip with a clean dry lint free cloth the technician left me and same results. He left me several clean lint free cloths to clean with.
Would it help to try cleaning the encoder strip with a clean lint free cloth with a small amount of rubbing alcohol?
I know not to use cleaning solution on the encoder strip.
And he said only the front side of the encoder strip really needs cleaning. Is that correct?

 

[Solventinkjet]

You can use 90% or above alcohol to clean it. I usually clean both sides because the sensor is actually seeing through the strip so each side can get dirty and affect it. Just be gentle as it's a new strip so it shouldn't need any hard scrubbing.

 

[Gino]

I take it, those are two different samples, cause the one 'T' has more blemishes than the other. Also, the word is written differently. What happens, if you change the direction of the file or use an entirely different file of some other colors and whatnot ?? This won't really solve anything, but it may bring to light some other suggestions.

 

[McDonald Signs]

Ok thank you I'll try that

 

[McDonald Signs]

It prints those blemishes in any file I print. I first noticed it starting doing it when I was printing a completely different file yesterday. The bad spots were in the exact same spot on the other print as well

 

[Jester1167]

It looked like a pinch roller to me as well. Could be contaminated media, try different media. I'm sure QC was the first to go with CoVID, it was with the recession.

 

[Jim Hancock]

Except I am a big fan of acetone for cleaning the encoder strip. Try that and let us know. Solventinkjet try it, you will become a believer...

As to the problem, did I understand it is on different medias or just one media? Did you examine the media with the issue in areas before printing? Does it repeat exactly at regular intervals? Is there a difference in the surface in the problem areas?

 

[Texas_Signmaker]

It looks like contamination on the media to me

 

[Gino]

Alright, let's try to isolate this thing. On the roll giving you the trouble, cut off a piece 54". Turn it sideways and run it through. If it shows up exactly at the same place as before turning, then it's definitely not the media. Use the same file, too. Are you adjusting for roll tension ?? You are unrolling plenty of vinyl before printing ??

 

[McDonald Signs]

There are no pinch rollers in the 2 areas where the blemishes are. Nothing touching the media in the 2 areas. Checked for oil on the rail from the technician visit and see none.
Plus if it was dripping or contamination from oil it would have to be getting on the media pretty often as it feeds thru to repeat the pattern.

 

[McDonald Signs]

I have tried 4 different 3M vinyls (Wrap, Reflective & Intermediate) we print on everyday and each one has had about half the roll used without any blemishes. It puts the blemishes in exactly the same place on all 4 rolls.
This problem just started a few days ago.

 

[McDonald Signs]

Also I had a tech put a brand new encoder strip and a new encoder reader on the printer 2 weeks ago.
I cleaned the encoder strip with a clean lint free cloth and it still does it. Haven't tried acetone or rubbing alcohol on the strip.
Waiting on the company that sent out the technician to replace the encoder strip to contact me Monday after Thanksgiving to see what they think.
Encoder strip is only 2 weeks old

 

[McDonald Signs]

Would something on the encoder strip or a bad encoder strip produce blemishes like that?
I've only seen the encoder strip make the print on the media "walk" or "step sideways" or produce jagged lines.

 

[Jester1167]

Just spitballing but;

Does your media rest on 2 rolling bars in the back like a plotter, or do you have some type of media handler? To me, it looks like media contamination. Because you say it has happened with different types of media, I would start looking at your process and machine and see where contamination could be transferred onto the media.

Also watch the printing process and make sure those areas aren't buckling because of the heat settings and making light contact with the head. It doesn't look like a head strike but I wouldn't rule anything out. Also, make sure nothing else is dropping down and making contact in those areas.

On our old Roland the tech taught us to use a folded piece of cardboard where the door sensor is so we could watch the head and media with the door up.

 

[Jim Hancock]

I asked earlier what type of dryer you have. If you are using a Benes dryer, check the position of the horizontal bars that allow the dryer to move front and back. Are these bars hitting the vinyl at the back of the printer?

You might also try hanging the media on the back media rod. You will have to remove the front media bar first and use the rod brake to keep the media from unspooling. Use the donuts as you normally would.

FYI, using this approach on banner material will minimize feed banding and reduce the strain on your feed motor.

 

[Pewter0000]

Have you tried using a smaller piece of media as opposed to off a roll? I'm wondering if the blemishes are coming from the way the media is being fed or from like, some sort of mechanical problem the head is encountering. It looks so oily, as if there's something dripping..