Printheads - In the 5440 and 5460 printers, with one head per color channel, the ink
tube exits the track and connects to the printhead. In the 5445 and 5465, with two
heads per color channel, the inbound ink tube from the track connects directly to
the left printhead of the pair. This printhead is termed the Master printhead; the right
printhead receives ink via a U-tube from the Master, so it is termed the Slave print-
head.
Ink level in the printhead is monitored by a system of thermistors ( = t resis-
tor). The thermistors change their electrical resistance according to temperature. The
air thermistor is isolated within a chamber in the printhead reservoir, while the ink
thermistor descends into the reservoir where it can contact ink.
Each channel has its own ink thermistor. In 2-heads-per-color (2x) machines, the
Master printhead (the left printhead of the pair, which also has the inbound ink con-
nection) has the ink thermistor. A single air thermistor is shared between pairs of
ink channels. So black and cyan share an air thermistor; magenta and yellow share
an air thermistor; and light cyan and light magenta share an air thermistor. The ink
thermistors and air thermistor in a channel pair (e.g., black and cyan) are a matched
set and must all be replaced together. The illustrations below show the arrangement
for the 5440 (fewest number of printheads) and the 5465 (greatest number of print-
Ink Thermistor
descends into ink
Air Thermistor
isolated from ink in air chamber
5400 Technical Training Manual
MacDermid ColorSpan Confidential
Page 22 of 39
MacDermid, Inc. 11311 K-Tel Drive, Minnetonka, MN 55343
Phone: 952-944-9457 Fax: 952-944-8507
