Printronix L5020 - Manual (Page 235)

Termination Resistors
237
Termination Resistors
For parallel interface configurations, the printer is equipped with
470 ohm pullup and 1K pulldown terminating resistors located on
the printer motherboard.
Generally, these terminating resistors are suitable for most
applications. If, however, the standard terminating resistor pack is
not compatible with the particular interface driver requirements of
your host computer, other values or combinations of pullup/
pulldown resistors may be necessary. For example, the
Dataproducts interface and some host computers require the use of
220 ohm pullup and 330 ohm pulldown resistors.
If you are experiencing communication problems between the
printer and host (double or missing characters), the cause may be
the value of the termination resistors on the motherboard. Contact
your authorized service representative for instructions on replacing
the termination resistors.