I’ve seen more scanner assembly and print quality issues with the CM34350 model than any other HP all-in-one (AIO) machine. I’m not going to bore you with lots of details, but I will give you a few pointers to isolate problems and find solutions to these print quality issues, which can include black lines and background printing, among others. Here is an image copy example to help you understand what I’m talking about.
Isolating the Problem
If there are lines on your copies, print a document from the computer. If the printed page from the computer also has lines, you have a print quality problem related to the print engine. Drums, transfer belts, and the fusing assembly can be the possible culprits for print engine print quality issues.
If the printed page from the computer (or an internal test page) does not have lines we know the problem is in the copy process. To further isolate the problem, make a copy from the document feeder and a copy from the glass. If there are lines when copying through the document feeder and not the flatbed glass then most likely there is something on the small glass strip to the left of the flatbed glass.
With the resolution these machines can copy, it doesn’t take much to cause a line down the page. Sometimes under low resolution settings you won’t see lines on copies if the line or mark is small enough. However, you’ll easily see the problem on a high res print. Also, if there are marks or lines on the white reference bar above the glass strip, the high resolution scanner will pick it up through the paper.
How to Fix Lines on Print or Copy
You’ll need to clean the glass. Glass cleaning solution works pretty well on most substances while alcohol typically does the trick on ink and some other marks. In desperation, I’ve been known to use nail polish remover. But, be careful! If you use nail polish remover do not get it on any plastic.
If the lines appear when copying using the document feeder AND the flatbed glass
there’s either something in the scanner optics or something in the scanner control board. You could run a few scanner tests in diagnostics mode to check the scanner lamps but it won’t always show you if you have a problem. Here are some options: (1) take the scanner assembly apart and attempt to clean out the optics, (2) replace the whole scanner assembly, or (3) replace the scanner control board. In my experience, replacing the scanner control board most often does the trick.
Note: If you’re buying a refurb or exchange unit, ask if the scanner control board comes with the unit or not. It is not sold that way OEM but some companies will sell them together if they sell refurbished printer parts.
Most of the time these copy quality issues can be resolved by just cleaning the glass. I can’t tell you the number of times I’ve gone onsite to fix a problem and the customer swears up and down that they have cleaned everything off the glass. Within a few seconds I find the mark and take care of the problem. The example I gave in the article is more like what I see with a scanner board problem. If there is only a line or two and you can’t figure it out, before you start replacing parts, get a second opinion from another tech. (If you’re the printer user, I suggest calling in a professional).
If you have additional questions or other tips please leave a message below.
Kevin Gumpp is a certified printer technician and freelance writer for Market Point. Market Point is a HP PartsOne Partner selling HP printer parts. If you have a question regarding this topic or have any other printer repair related questions or topics for which you would like more information, please send an email to firstname.lastname@example.org.