Help! My Laser Printer is Making Horizontal Black Lines


laser printer horizontal black linesThere’s no worse feeling than the satisfaction of finishing a print job, only to find out the pages have been ruined by horizontal black lines.

Office equipment may have the occasional malfunction, but if your laser printer is causing horizontal black lines consistently then you have a greater problem on your hands.

There are two reasons why your laser printer is causing horizontal black lines.

This article will teach you two different ways you can get to the root of the problem and get back to making clean copies.

In the end, we’re sure you’ll find the problem is easier to fix than you might think.

Why is My Laser Printer Making Horizontal Black Lines?

If you’re consistently running into problems with your laser printer and horizontal black lines, the first thing you have to do is identify the root of the problem.

Two Reasons Why

Reason 1
There could be two causes of this problem, and identifying the root cause couldn’t be more simple.

If you’re getting black lines on copies and not on prints, then you know something is interfering with the optics.

Usually that means there’s some sort of material on the glass where the scanning is being done. There’s something interfering with the machine’s ability to get a clear view of the image.

If your laser printer is making horizontal black lines on copies but not prints, a good cleaning should help solve the problem.

Even the slightest speck of dust on the optics could cause defective prints, so it is important to keep equipment clean.

On the bright side this one is the easiest fix, and least expensive since you usually don’t have to replace anything. The other scenario down below is a bit less ideal.

Reason 2
You could have a whole other problem if you have horizontal black lines on both copies and prints.

Black lines on copies and prints means there is an issue with the drum. A drum is like a camera, a photoconductor; it’s what takes the picture.

The drum is also delicate, so if it gets disrupted there will be defects on every print or copy you make. In some cases the drum can be repaired, but in most cases it will need to be replaced.

Drums are susceptible to wear and tear. Everyone with a multifunctional copy machine will have to replace the drum at some point in time.

Think of it like replacing brakes in a car. Eventually, every piece of equipment with moving parts will need maintenance and repair.


If your laser printer is causing horizontal black lines you either have a problem with the optics or the drum.

Cleaning the optics and replacing the drum should fix the problem in most cases.

If problems still persist after cleaning the optics, or you don’t feel comfortable changing the drum on your machine, give us call.

We’re happy to help you diagnose the cause of any printing defect you might have. Contact us today.

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