Epson LQ-510 User Manual page 30

WARNING: Never run the self test using paper that is
narrower than A4 size (8.27 inches or 210 mm) or letter
size (8.5 inches or 216 mm) to prevent the print head from
printing directly onto the platen.
6. Press the LOAD/EJECT button to load the paper.
7. Press the ON LINE button to start the self test. A list of DIP switch
settings is printed first, followed by a series of characters. The
self test continues until the paper runs out or until you press the
ON LINE button.
Testing the Printer
Setting Up the Printer
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