Troubleshooting dot matrix printers

• If the printer self-tests OK but will not print jobs from the computer, check the following:

• Dip switch settings

• Proper driver for your application software

• Bad or disconnected cable

• Some printers have both serial and parallel connections. If one does not work, change cables and try the other. Be sure to change any dip switch settings needed by the printer to acknowledge the change. If this works, you may have had a physical problem with the output port on the computer or the input port of the printer that you tried the first time.

• If a dot matrix printer shuts down and recovers frequently, it may be having problems with its ``thermistor''. A thermistor is a device used to keep the printer from overheating. Try replacing this part before you replace the entire print head.

• Some printers can be set by dip switches for unidirectional or bidirectional printing. Bidirectional is normally faster, but might cause problems with graphic output for some combinations of applications and printers. If you suspect this problem, reset your dip switches for unidirectional printing.

• If your output is double-spaced when you expect single-spaced, you may be getting an extra Carriage Return and Line Feed at the end of every line. Reset the dip switch(es) controlling this.

• If your print quality is poor, first check the ribbon for wear. Also examine the print head spacing. Your head may be too far away from the platen for your current paper thickness. If adjusting the spacing does not solve the problem, clean the print head itself with a cotton swab dipped lightly in alcohol.