How to troubleshoot a printer

The moment you connect a printer, there are all sorts of problems you will face. Here are some tips for some common problems.

Printer will not start

This is accompanied by the refusal to self test. Check the thing is switched on first and that the power cable is properly plugged in. If not, it is going to get messy.

The printer's memory, program ROM and ASIC (Application-Specicific Integrated Circuit) or microprocessor could be responsible and these are beyond most people's technical ability.

The printer insists it is out of paper when it has loads

The most obvious sensor failure is a paper-out error message when paper is available. Erratic carriage returns or print spacing is often the result of a problem with the position encoder sensor. Looks like the sensor will have to be replaced.

The paper does not move or is folded into an abstract origami figure

The drive-train components are not working properly. Check your motor windings, and connections should be checked together with wiring and power supply voltages.

However, sometimes it is not as bad as all that. A lot of paper faults are caused by using the wrong sort of paper. That nasty cheap stuff bought in a car boot sale may look good, but it is often not designed for the rigours of being mangled through an inkjet. Sometimes it flakes and bits of it get into the workings of your printer. Buy a ream of good stuff and see if that helps.

Check to see that paper has not got into the internal workings of your printer, and fish it out.

Dot-matrix printers

Some people may still use these dinosaurs particularly for low-quality mass print runs. Besides age, many of these printers have unique problems of their own.

Firstly, if the printing gets faint, it means that the ribbon needs replacing or else the ribbon advance system might have had it.

Check also that the printhead to paper spacing is appropriate for the thickness of paper; it may be set for envelopes. Otherwise, the printhead or drive circuits could be the cause. These simply wear out.

Missing dots on the paper means the printhead dots are clogged or broken. Try cleaning them with an alcohol-based solvent. However, if the pins are bent or broken, you will need a new printhead.

If not, then the driver's output transistor is faulty (another side effect is when there is a continuous horizontal line of dots on the page).

Inkjet printers

Never in the field of printer technology did so much depend on good-quality paper. Many of an inkjet's problems are based on people using low grade paper and then moaning that the picture quality is bad or their machines become clogged.

When you are shopping don't consider anything less than 90gsm in weight (preferably 100 gsm) and, if you're thinking of printing pictures, non-absorbent glossy paper.

Other reasons for poor-quality printing can be caused by unsuitable printhead to paper spacing and dried ink on the printhead.

A lot of printers have self-cleaning functions and these should be run periodically, even though they burn up your ink reserves.

Some machines have separate power supplies and these can cause the printer not to work at all. Fortunately separate AC adaptors can be tested and economically repaired.

If a printer will not print or self-test and you have tried removing and replacing cabling and reinstalling driver but to no avail, you might need a new printhead. These are cheap enough.

Most serious inkjet printer problems are solved by purchasing a new machine. Often it can cost more than the original printer to repair some of the minor faults in an inkjet.

Laser printers

Lasers are cheaper to repair and often do not need replacing. However, they have some unique problems of their own.

Diagnosis of laser problems are typically aided by an error description or number displayed on an LCD panel on the printer, or a printed warning. If you look at the manual it will provide lists to help you.

Printer always shows "Warming-up" warning:

• Faulty data cable
• 
  
• Faulty interface circuit

You get a "Paper Out" warning:

• If paper is actually present or the paper tray is not in properly
• 
  
• Non-working tray sensors

Your paper keeps jamming:

• Poor-quality paper
• 
  
• Worn pickup assembly
• 
  
• Fuser unit problem

You keep getting "Error" warnings (both trips to the workshop):

• The laser scanner unit is broken
• 
  >li>Scanner and hardware driver connection is down
• 
  Paper comes out all black (off to the workshop):
  
• Primary corona in EP cartridge
• 
  
• Electronic logic fault

Faint print:

• Low toner level in EP cartridge (replace cartridge)
• 
  
• Unsuitable paper quality
• 
  
• Transfer corona assembly (workshop)
• 
  
• Fault in high-voltage power supply (check it is connected properly, you might need to replace it)

Speckled print:

• Primary corona control grid (workshop)
• 
  
• High-voltage power supply (check it is connected properly, you might need to replace it)

Vertical white lines:

• EP cartridge (replace)
• 
  
• Transfer corona assembly (doomed, take to workshop)
• 
  
• Scanning and laser assembly (doomed, take to workshop)

Missing right-hand or distorted text:

• Check toner level or replace EP cartridge
• 
  
• Check scanner and optical alignment using software that came with machine

Incorrect image registration:

• Check or replace pickup rollers, sometimes paper gets stuck in there
• 
  
• Check or replace drive train (workshop)

Rough print appearance:

• Troubleshoot the electronic logic circuit with software provided, otherwise take it to the workshop

Smeared print:

• Check fusing roller and cleaning pads
• 
  
• Check or replace static discharge comb
• 
  
• Check the drive train and paper path

Distorted images:

• Check paper path
• 
  
• Check or replace the scanner unit