Topic: Scanner problems... suggestions???

[Wolfhound]

Damn forums timed out on me as I was typing this the first time, so will try to keep it shorter this time... 

I'm having trouble with a scanner (Dell 948) which is warping maps that I scan in.  The vertical lines are coming out fine, but the horizontal lines are coming out not horizontal (scanning at ~150 pixels per inch) with a shift of about 8-15 pixels across the page width (on every single page scanned).  I usually end up manipulating the image slightly using Paint Shop Pro to "twist" it about 0.2° to 0.3° to try to partially straighten the horizontal shift, but this also shifts the good vertical lines slightly out of vertical. 

I'm using engineering paper for drawing the maps (so that I can see the grid through the paper, which then doesn't come through on the scan very well- as intended), so I know that the lines on the paper are truly vertical and horizontal. 

This results in needing to do a lot of work to try to fix the "out of square" problem on a lot of the maps (especially those of larger structures that should be relatively square, although I suppose I could claim that due to some funky law of physics on this world nothing is square? ). 

Does anyone know if it is possible to "re-calibrate" or adjust how a scanner works for such things?  Is this an easy fix without throwing it out the window and buying a new (better) scanner? 

[GrumpyOldFart]

Hmmm... I'm not familiar with that particular scanner/printer, but as someone who used to work on copiers, printers and faxes for a living, I have a few ideas.

"Vertical" lines are good. I assume you are defining "vertical" as "parallel to the direction of scan," that is, lead edge to trail edge. Good. That tells me that the optics and the frame that holds them aren't hopelessly misaligned. If, for example, the trail edge of the printed document was narrower or wider than the lead edge, there would probably be nothing you could do except throw it away and get a new one.

"Horizontal" lines, those perpendicular to the direction of scan, are displaced by several pixels on one side relative to the other. That suggests to me that one side of the scan carriage is dragging. If the scan carriage has drive cables only on one side instead of both (most are only on one side), I'd expect the problem to be on the side without the cables. Depending on how it is laid out, it could be something very simple, for example idler wheels on the non-cable side so it will roll freely to keep up with the driven side. If dirt gets between the wheels and their axles, they drag and that side of the image "lags".

Suggestions:
1. If your printer has a document feeder, use it. Often the scan carriage will stay stationary and just scan the document as it goes by, if there is a document feeder in use. This doesn't actually solve the problem, but it does bypass it. If you use the document feeder, clean the platen glass with furniture polish, not with glass cleaner. Glass cleaner strips the surface and makes it try to grab the document. You want the surface of that glass to be slick, so much so that if you toss a sheet of paper on it, it skates right off the other side. Rain-X windshield treatment will do the same thing.
2. If that's not an option, remove the platen glass and clean all accessible wheels and rails in the scan carriage with a mild soap and water solution and dry them thoroughly. Don't use alcohol as it makes synthetic rubbers brittle over time. In particular, check idler wheels to make sure they spin freely. If they don't, a drop of a light oil at the interface of wheel and axle may clear the grit. Sewing machine oil is a better choice than 3-in-1 oil, as 3-in-1 has a dissolved plastic of some sort in it that creates a coating when it dries. CRASH PRIORITY IMPORTANCE: Do not loosen any screws with a paint spot on the screw and the area around it. These are screws pre-set at the factory to keep the image square between the original, possibly several mirrors, and the part of the machine that actually registers the image (usually CCDs). If you loosen them, you'll never get the image square again.

Hope this helps. I can't tell you much more than that without knowing any more about the particular machine and/or seeing the symptoms myself.

[Wolfhound]

Yup, you understood what I was getting at with the distortion.  I never thought about that as being the possible cause, but it would make sense (the printer/scanner is about 5 years old now so very well could be the case). 

It does have a document feeder, so I'll give that a try tonight when I get home (if I can figure out how it works, as I've never used that feature before).  And if it does, then down the road I'll try the cleaning method you suggest.  But in the short term, if the document feeder works to straighten the image, I'll plan to re-scan a lot of the maps using that method in the short term. 

Very much appreciate the suggestions. 

[GrumpyOldFart]

I never thought about that as being the possible cause, but it would make sense (the printer/scanner is about 5 years old now so very well could be the case).

My experience has taught me that about 90% of what goes wrong with anything electronic or electromechanical can be described with a single word: dirt. More often than not, a problem in anything of this sort can be solved simply by cleaning everything you can reach.

 

[Wolfhound]

Yup, that worked (sort of anyways).  Just having a hell of a time to get the feed to work.  If I scan more than one page at a time the graphics software crashes as soon as the file(s) are uploaded to it, whereas if I scan one page at a time they don't feed half the time.  And when they do, they don't feed perfectly straight, so it is still slightly crooked.  However both the vertical and horizontal are off by about the same proportion of pixels so if I then rotate the entire image slightly it at least fixes it.  So this is a definite step in the right direction, if I can just get the feed to work in the short term (until I have time to spare to tear things apart and get it cleaned out inside, which I'm reluctant to do until I get them scanned in just in case I do mess something up). 

But thanks for the help, as it is at least working a whole lot better than it was. 

[GrumpyOldFart]

...whereas if I scan one page at a time they don't feed half the time.  And when they do, they don't feed perfectly straight...

Clean the takeup rollers on the document feeder (the ones that grab the paper and pull it in), and clean the platen glass with something that leaves a slick surface on the glass, like Pledge or Rain-X. Often, document feeders have a rubber belt on the underside that feeds the paper across the platen. It may be worthwhile to clean that too, but usually they can be relied on to grab the paper and bring it along. The main thing is to make sure the glass does not grab the paper and try to keep it in place. As I said earlier, if you skate a piece of paper across the glass, it should skate right across it and right off the other side, it should be that slick. You won't get that with any kind of glass cleaner that uses ammonia or vinegar, and best results will be obtained from something that leaves a waxy coating. As a test, try to deal a hand of cards onto the platen. If it's slick enough, it should be nearly impossible to keep the cards from skating clean off the other side, you want that glass as nearly friction-free as you can get it.

If I scan more than one page at a time the graphics software crashes as soon as the file(s) are uploaded to it...

Can't help you with that one. It may be a dirty sensor in the document feeder (probably one of several, your guess is as good as mine which one it would be or how to find it), or it may be a software problem.

However both the vertical and horizontal are off by about the same proportion of pixels...

If it's feeding crooked but the optics are square, it should be off by exactly the same angle in all directions.

Also, there's another little oddball thing about any machine that feeds paper. Stacks of paper tend to develop a static bond between sheets over time. Simply riffling the stack will break that up. Riffle it on both ends.

[Wolfhound]

I'll try cleaning the glass and roller that pulls it in.  Do you think that the Pledge or Rain-X will also reduce smudging?  I am seeing  a little of that after a couple of pages go through (since they are pencil drawings and some have a lot of dark areas shaded in)?

As far as the crashing, whenever I had scanned in the past it started up another instance (even if it is already open) of the graphics program I use to save the images in (Paint Shop Pro), so I suspect that it is doing so for each page and it can't start that many multiple copies of the software at the same time.  So don't think there is anything I can do about that.

[GrumpyOldFart]

Do you think that the Pledge or Rain-X will also reduce smudging?

It might, since

I am seeing a little of that after a couple of pages go through (since they are pencil drawings and some have a lot of dark areas shaded in)?

suggests that the glass has enough drag that it's trying to hang on to some of the graphite on the surface of the paper. It might help to brush the sheets with a soft brush before you scan them, to take off any loose graphite.

So don't think there is anything I can do about that.

I don't think so either. Sounds like a software issue, that I don't know how to solve. I dunno from Paint Shop Pro.

What I said about riffling stacks of sheets before feeding them? The most common effect of that static bond between sheets in a stack is that the takeup rollers will try to take more than one sheet at a time.

[arakish]

Sorry for late input.  Like GOF suggests, clean EVERYTHING in the scanner.  However, instead of Pledge or Rain-X, I use a cleaner specifically made for cleaning electronics.  I do not know what the cleaner is since I buy packages of wipes impregnated with the cleaner.  The package label simply says "Electronics Cleaner Wipes" due to being a Wal-Mart product.

I have a scanner at home that is literally 15 to 20 years old and it still works as good as any modern scanner because I clean it once a month.  When cleaning, I literally take it completely apart and clean all parts as I put it back together.  Additionally, I use canned air to blast away any dust as I put it back together.  By doing this once a month, I have never had any problems with the scanner.

In fact, the scanner is so old that no drivers exist anymore for it any newer than Windows XP Pro versions.  I simply use the generic drivers that Windows 7 and Windows 8 installs.  All my software (Photoshop, Paint Shop Pro, GIMP, et. al.) already has built-in TWAIN applets.

rmfr

[GrumpyOldFart]

I'm not suggesting Pledge or Rain-X for the electronics, or even the plastic and metal parts... only for the glass. With the electronics, either will leave a film that I can't promise will be conductive. For rubber, a slick surface is exactly what you don't want. For everything else, well... it won't hurt anything, but I can't promise it will get it actually clean, either.

For plastic and rubber, a mild soap solution does well. Most electronics cleaners evaporate too quickly, which dries out the rubber and plastic and makes it go brittle over time. For metal parts that are not part of the actual electronics, like scan carriage rails, a lot of the time you can just wipe them down. If that doesn't get it, alcohol usually does well.

For the actual electronic parts, alcohol or an electronics cleaner does well. For contact points, like the plug-in edges of circuit cards, one of the most reliable ways to get one clean is to go over it with a rubber eraser. For pin type contacts, taking a piece of styrofoam and pushing it on and off the pin a few times tends to do about the same job, and doesn't run nearly as much risk of bending the pins like a rubber eraser will.

[Wolfhound]

Not sure if I'm going to be able to clean any of the internals, as I can't figure out how to remove the glass to get to that part of the unit.  Which is what I would prefer to do since the feed system is not working as smoothly as I had hoped.

But I will try the Pledge on the glass idea tonight, which hopefully will help with the paper feed problems.  Have already tried an alcohol type of wipe on the glass and tried wiping down the rollers that pull the paper into the unit (with a dried out alcohol wipe), which seemed to help a little. 

[GrumpyOldFart]

Printer manufacturers have always had a bad habit of hiding the screws. Then again, a lot of times it's only held in by the plastic case, which is sometimes held on with hidden screws (you may have to open it up as if you were changing an ink/toner cartridge and come at it from the inside), and sometimes held in place with plastic tabs that can be released by sliding a small flat-tip screwdriver alongside them.