Epson TM-U590/U590P Operator's Manual page 34

If the self test works properly, check the following:
1. Check the connection at both ends of the interface cable
between the printer and the computer. Also make sure that this
cable meets the specifications for both the printer and the
computer.
2. The data transmission settings may be different between the
printer and computer. Make sure that the printer's DIP switch
settings for data transmission are the same as the computer's.
You can print the printer's interface settings using the self test.
If the printer still does not print, contact your dealer or a qualified
service person.
The printer sounds like it is printing, but nothing is printed.
The ribbon cassette may not be installed properly. See the
instructions in Chapter 1.
The ribbon may be worn out. Replace the ribbon cassette as
described in Chapter 1.
The printout is faint.
The ribbon may be worn out. Replace the ribbon cassette as
described in Chapter 1.
A line of dots is missing in the printout.
The print head may be damaged. Stop printing and contact your
dealer or a qualified service person.
3-2 Troubleshooting