Re: [gentoo-user] Scanner and weird streaking

[Michael]

On Friday, 30 December 2022 02:28:32 GMT Dale wrote:
> Howdy all,
>
> I have a HP scanjet 4570c flatbed scanner.  I bought it used years ago
> and most of the time, it works just fine.  On occasion tho, I get
> something weird.  When I scan something, it adds some pinkish colored
> streaks.  I took a scrap sheet of paper and scanned the back of it. I
> used a magic marker on some text that was there, also drew a smiley face
> on it as well.  Anyway, the side with print is on the opposite side.
> Basically, it is also seeing the back side of the paper.  I'm not sure
> if that could cause this weird streaking but wanted to mention it.

I've come across the pink hue artefact on an old HP scanner, but can't recall 
the model.  It is not related to the print of the opposite side becoming 
visible, which is caused by a high light exposure setting.  You need to reduce 
the exposure to a level where you can see the primary print clear enough, 
without the back side bleeding through.


> At first, I thought it was something on the glass so I disassembled the
> thing and cleaned it as best as I could.  When I put it back together, I
> concentrated on the back side of the glass, since I have to disassemble
> it to clean it.  I also clean the side the document goes on regularly.
> If it changed, I can't tell it.  Another odd thing, the streaks change
> depending on the document.  Sometimes you can barely see it, other times
> it is awful.  I've not been able to reason out what makes the difference
> tho.

Cleaning the glass won't affect the pink hue.  I dismantled the scanner and 
cleaned the glass too, with no improvement.


> I've got about the same results using Scanlite, Scanpage and XSane
> software.  XSane may be a tiny bit better but it does vary at times.
> There's not a lot of settings available.  I tend to use either 100dpi or
> 300 dpi for resolution thingy. I fiddled around a bit but it doesn't
> seem to help.  This is a link to the page I described above.  It's a
> little sizey so I didn't want to attach, for those who have email
> clients that puke a lot.  lol
>
> https://freeimage.host/i/HTQLpWb
>
> You may notice that it is a little heavier at the top and gets lighter
> as it goes down.  I've checked the glass, I can't find anything that
> would cause this.  Is my scanner just going bad?  Am I doing something
> wrong with a setting or something?  Any ideas?  Thoughts?

The pink hue is probably due to the scanner bar going bad.  Some fixes, which 
did not work in my case, are as follows:

1. Reset internal chipset:  Plug it in, switch it on, then pull the power 
lead, followed by the USB.  Wait for a minute or longer to discharge, then 
reconnect, power on and try to see if the problem is fixed.

2. Overheating: More of a problem in the summer.  Use a desk fan while 
operating to see if it makes a difference.

If none of the above work, then the scanner bar needs replacing.  Probably 
time for a new scanner, unless you can find a donor scanner for the scanner 
bar.