Do-It-Yourself Office, Fuser

DIY Repair Tip; Symptoms of a Bad Fuser

What is a Fuser Assembly?Fuser Rollers
The fuser assembly is the part in a copier, Laser printer or Laser fax machine that fuses the toner to the paper.  Toner is made of crushed plastic and carbon black for color.  Once the image is transferred to the paper you need to fuse it into the paper.  If you have ever stopped the paper before it goes through the fuser you would find that the toner will come right off.  It needs to be fused.  There are two important steps to fusing and those are…

  1. Heat;  Heat is applied to a teflon or non-stick upper roller or sleeve/film with halogen lamps or a heater element.
  2. Pressure;  Pressure is used for fusing toner to the paper with a pressure or lower roller.  They use heavy springs on the front and rear side that press the lower roller to the upper roller or film to aid in fusing.

Symptoms of a Bad Fuser;

Ghosting or double images,streaking, black lines  and smudges; also Jamming;
These marks are often on the top and bottom of the pages.  These symptoms are caused from the teflon material on the upper roller or film being worn off, ripped or scored.  The solution is to replace the fuser as an assembly or replace the worn roller or film parts.

Error code;  If a problem exists indicating a fuser problem it will stop the machine from operating and give an error code.  The codes are all different for each make and model.  There are three major items that go bad on a fuser assembly that would give an error code. 

  1. The lamp or the heater element is bad
  2. The thermal fuse is bad.
  3. The thermistor is bad.  temperature sensing device

There are a few other problems you may encounter with a fuser such as; Broken gears, bad lower roller, jamming (this is most likely a bad roller) 

Separator Fingers; These scrape or separate the paper off of the roller because the paper tends to stick to the upper roller and needs help to seperate it off of the roller.  (that  is why they use a Teflon material on the upper roller/fim) These scrapers build up with toner, wear down and break causing jamming.  Accordion jams are one of the types of  jams you would get in the fuser.  It folds up the paper in an accordion because the paper can’t get past the fuser.

You may be interested in this article; Printer Fuser Units-New Versus Refurbished

Here is where you can ask a question or comment on this post regarding fuser assemblies or symptoms mentioned earlier.


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