Fax Machine Repair

Fax machines are still active in many homes and offices. This Fix-It Guide on fax machine repair tells how a facsimile or fax machine works, what often goes wrong, how to identify a fax machine problem, and what parts and tools you will need to fix it. It then gives step-by-step instructions for how to service a thermal fax machine and how to replace the exposure lens in a thermal fax machine. It also refers you to instructions for servicing a plain-paper fax machine and to other Fix-It Guides as appropriate.

How Does a Fax Machine Work?

Fax Machine Repair

Canned air is useful for cleaning dust and paper particles from a fax machine.

A fax machine is an electronic device that scans a paper image and transmits it by modem to another fax machine.

A document fed into a fax machine passes over a device containing a single row of light detectors. The device scans the page, producing an electrical signal of varying voltage that represents the dark and light parts of the page. The pattern is sent along a telephone line to the receiving fax machine that decodes the signal and translates it into an exact image, a facsimile.

The two types of fax machines, plain paper and thermal, are distinguished by the paper they use. A thermal fax machine contains a thermal printer with heating elements that prints rows of dots on a roll of heat-sensitive paper. A newer plain-paper fax machine contains an ink-jet or laser printer to print a copy of a document being sent to it.

What Can Go Wrong with a Fax Machine?

Either type of fax machine contains few serviceable parts. Routine maintenance, however, will help avoid most problems. The best course of action is to use quality supplies and periodically clean the machine.

Fix-It Tip

The first thing to check with a problem fax machine is the incoming telephone line and connections. If in doubt about the incoming line, plug a standard telephone into the phone plug on the wall and listen for a dial tone.

How Can I Identify a Fax Machine Problem?

Symptoms will help you determine the cause.

  • If a fax machine won’t work, make sure the power is on at the outlet and test the electrical cord.
  • If the fax can’t send or receive documents, make sure that the phone line is connected and not damaged. Check to be sure the line is plugged into the correct fax port. Test the wall jack and replace it if it is faulty (see the Telephone System Fix-It Guide).
  • If the fax machine can send but not receive (or vice versa), check the phone line as above and replace the lamp if burned out.
  • If the fax still will not function properly, take the unit to a service center or replace the unit.
  • If there are marks or blank spots on incoming documents, open the cover and clean the glass with a clean lint-free cloth dampened with denatured alcohol.
  • If a plan-paper fax machine leaves marks or blank spots on documents, open the cover and wipe up any spilled toner. Clean corona wires if dirty, or replace the drum if damaged, following the manufacturer’s instructions for replacement.
  • If a thermal fax machine won’t print, locate the thermal head and clean it by wiping it with a clean lint-free cloth dampened with denatured alcohol. Make sure that the paper is installed correctly because the printer will print on only the coated side.

Fix-It Tip

Periodically clean out the interior of a fax machine with denatured alcohol and canned air, following the directions in the unit’s owner’s manual.

What Do I Need for Fax Machine Repair?

There are so many models of fax machines that replacement parts are best found through the original manufacturer or authorized parts supplier. To disassemble and check a fax, you’ll need some tools:

  • Screwdrivers
  • Denatured alcohol
  • Canned air
  • Lint-free cloth
  • Small brush

What Are the Steps to Fax Machine Repair?

To service a plain-paper fax, refer to the Computer Printer Fix-It Guide.

Service a thermal fax machine:

  1. Unplug the unit from the power source and the incoming telephone line.
  2. Open the unit and wipe the platen using a cloth dampened with denatured alcohol.
  3. Allow the platen to dry thoroughly before use.
  4. Use a small brush or canned air to remove dirt and dust from the paper trough.
  5. If accessible, wipe the exposure lens and mirrors with a lint-free cloth.

Replace the exposure lens in a thermal fax machine:

  1. Unplug the unit from the power source and the incoming telephone line.
  2. Turn the unit over and remove the bottom housing.
  3. Once the bulb is cool, twist it out and pull it from the socket.
  4. Replace the bulb with an identical model, avoiding touching it.


Keep fax machines away from heat sources that can dry out paper, chemicals, or toner.