Printers: Output is Gibberish

Most people have a bit of experience of printers suddenly chucking out pages of "rubbish" - apparently random characters or a strange numeric language looking nothing like what was seen on the screen. If this happens it is usually either.

• the wrong printer driver has been selected
• the file is corrupted
• there was an interruption in communication.

Printers work from a data stream which announces new print jobs and specifies different ways of communicating the data. For instance:

• More complicated printers might suspend a job until the user submits a PIN. The print language may have to select the media on printers with multiple trays.
• A page can be specified as ASCII or UTF text, as vectors, as text formed from vectors but communicated as a "font" of vectors and hints on their use or as a bitmap.

In other words, what appears on the computer screen and prints on the page may look nothing like either as it moves through the connection.

Wrong Language.

At one time this kind of fault would have been wrong print language selected. Computer drivers and printers normally auto-select between languages these days. If the fault is seen the chances are that the print driver doesn't match the printers capabilities correctly.

Disconnection.

Another possibility is that the communication stream was interrupted. Is a print switch in use that was changed after the print stream started? Network connections using TCP/IP often will cope with a disconnection but it isn't guaranteed

Drivers.

If it happens persistently its probably a print setting on the computer - the driver is sending a print language the printer cannot interpret so it is printing the text. Often this results in some printing at the top of pages what are otherwise a lot of blank pages.

It is unlikely for this fault to be caused by the printer. Try printing a configuration page - this exercises the printers internal logic without the computer being involved. If a configuration page is good but data from outside is not it suggests the computer drivers as the most likely fault or an obscure fault in the communication link.

Download drivers from Microsoft or the printer manufacturer. Be sceptical about the sites offering a nice blue or green button with "Download Now" in big friendly letters. Some seem to be offering malware. Linux users will find drivers for most printers available in CUPS or HPLIP.