That d@mn Colorspan!

[Ddave72]

Argh! After getting the ol' beast tuned up & running right, last week & 1/2 it hasn't seen much use (still keeping it clean etc), and now the bleedin' thing's glitching its prints.

OK, I've gotta describe this better. Example (from 10 minutes ago):

Equipment: Colorspan DisplayMaker 72uvx

RIP: Onyx

Media: coro, 48x96

Print size: most of a full sheet (48x90)

Problem: Prints fine... at first. 48" into the print, it starts printing "dirty." 5 to 5.5" later, the Y-axis (feed direction) registration goes WAY the F off... at least 0.25". Stays that way for almost exactly 3", then is fine again, but continues to print "dirty." (that's the only way I can describe it... looks almost like headstrikes, but the sheet's flat & clean, so can't be... right?)

So WTF is going on? The old girl's been behaving herself admirably since my cleaning and calibration blitz a few weeks ago, until now. The way the print is falling off, then snapping back into reg is absolutely baffling me.

Anyone got any ideas? I can't go on getting half a print and half trash out of each sheet of media.

Thanks in advance,
Ddave

 

[P Wagner]

Initial thought is that the linear encoder strip (aka t-fence) or the encoder sensor tends to be the general cause of y-axis misprints. Locate and clean the strip and sensor, but do not use any harsh cleaning agents, as you can damage the strip or sensor. A lint-free cloth and IPA are generally a safe choice for most printers.

 

[Ddave72]

photo of my crappy print

OK, here's a photo of the worst part of the print... note how it falls way off, then snaps back into reg.

 

[Ddave72]

Hey, Castek. Yeah, someone here just said maybe the encoder. Naturally, the manual is silent on the subject (as it seems to be on anything I really need to know). Found the strip; any idea where the sensor is? And I'm not so sure about cleaning it with IPA... although the hops would certainly provide a clean, crisp finish-- wait, you didn't mean India Pale Ale, did you.

Gonna need a few tonight after dealing with this b*st*rd printer...

 

[J Hill Designs]

yeah the IPA (india pale) is for you, after cleaning the encoder strip with IPA (isopropyl alcohol)

 

[P Wagner]

Hey, Castek. Yeah, someone here just said maybe the encoder. Naturally, the manual is silent on the subject (as it seems to be on anything I really need to know). Found the strip; any idea where the sensor is? And I'm not so sure about cleaning it with IPA... although the hops would certainly provide a clean, crisp finish-- wait, you didn't mean India Pale Ale, did you.

Gonna need a few tonight after dealing with this b*st*rd printer...

The sensor is normally located on the carriage (I can't say that I am familiar with your printer model, so it is hard to provide more specific info).

 

[Ddave72]

Well, I cleaned the encoder strip... lots of dust, hopefully that'll do the trick. According to the "Installation Instructions for Carriage Assemblies," the sensor is buried deeeep inside the carriage, and apparently requires serious surgery to access it, including a full power-down and major disassembly, so the sensor itself is gonna go uncleaned. Clearly, they really don't want me d!cking around with it, so I won't.

Unfortunately, the only way to tell if this worked is to burn another sheet of coro (well, the other side of this one, anyway, since the first side's already pooched). With luck, I'll have a happy flatbed again.

One thing about that encoder strip: there is some (to my eyes) serious wear on the edge of it. Co-workers claim the strip was replaced *recently* (which may refer to geologic time), but really, is it NORMAL to have a lot of wear on the edge?

The wear is actually (mostly) beyond the point where my prints have been glitching... it seems to be concentrated in the area where the carriage stops and returns, which I guess would make sense as a high-wear area. I suppose this wear would probably have an adverse effect... or no?

 

[P Wagner]

On most printers, there is (or should be) no physical contact between the linear encoder and the sensor, or anything else. The job of the encoder/ sensor is to keep track of the position of the carriage as it prints.

It does this by counting the lines or other markings that are present on the strip. If those markings are obscured by ink, dust, or other contaminants, that can cause the type of problem that you are seeing.

 

[Ddave72]

OK, looks like cleaning the encoder strip did the trick. Either that, or (as the old saying goes) a watched printer never glitches.

Castek, thanks so much for the assistance! I'll be knocking back an IPA for you after work (and I don't mean isopropyl)!

This bloody printer... I swear, I've had British cars and Italian motorbikes that were more reliable... and if you know anything about either, you know what a huge statement THAT is!

Thanks again, and be sure to watch this space for the next thrilling episode of... "DDAVE72 AND THE COLORSPAN OF DOOM!"

 

[Hzone15]

Hey Dave, I used to own and operate ColorSpan equipment and know the frustrations you are going through. I found myself a really good dealer North Light Color out of MN who used to sell a bunch of ColorSpan's and retained a few of there technicians after they were purchased by HP. They could be a good reference to you and I know they have an office in Atlanta and Chicago as well as MN.

Future reference maybe they could be of service to you.

 

[omgsideburns]

The way you are getting that ghosting looks like the media is slipping.. unless that shadow is supposed to look like that. That can be related to feed tension, roller pressure, or needing to use the takeup.

Also, per the manual, you should clean the encoder strip with your solachrome cleaner. I clean it with alcohol fairly often though. Usually after I wipe the bearing rail which is a daily thing. Dirty encoder can cause all kinds of goofy issues. Regarding the rough edge on the encoder, mine is fairly worn looking also but I don't think the sensor reads the very edge of it. I've taken that thing apart and put it back together so many times.. ugh. It's not difficult to access if you need to adjust it if it IS rubbing. I can send pictures of how to check.

Random ink and overspray can be caused by static or dirty tension rollers too.

 

[Hoop2125]

don't use IPA!!!
I did this and it eventually took the lines off. When i realized this it was 7pm and the job had to go out. (I have an HP H35500, so i'm not sure yours is the same)
I came up with something that even surprised my tech, I removed the strip and aluminum backer strip. Then I peeled off the encoder along with lots of adhesive foam tape that attached it to the aluminum strip. I then took a small bowl of mineral spirits and soaked it for a few minutes. The adhesive softened and all the foam came off. Then i took some fresh solvent and a lint free cloth and carefully removed any remaining residue. While the strip was drying, i went to the store and bought some foam mounting tape. It took two layers to equal the original thickness. I put the whole darn thing back together and low and behold it worked. That next day i ordered a new strip and there it sits in the box it came in.