tor; if an ink thermistor reaches the corresponding threshold value, the printer con-
cludes that the ink reservoir is empty, and so the ink pump is commanded to run. The
pump runs a fixed interval of time, then the ink is allowed to settle in the printhead
reservoir and another set of readings is taken. If there is still no ink detected by the
thermistors, the pump is commanded to run for another cycle. (Note: there are soft-
ware rules about when the pumps are allowed to run; for example, a pump will not
run while the printer is in Sleep mode.)
A perfectly-matched triplet of thermistors should have same value when all three are
actually in air. If an ink thermistor has slightly higher value than its air thermist or,
that is acceptable; but an ink thermsitor in air that reads lower than its air thermistor
opens the possibility for ink overfills of the printhead.
If no ink is detected by the thermistors after a few pump cycles, an Action is dis-
played on the control panel indicating that the printer is unable to fill the printheads
with ink. This can be the end result of a number of possible causes:
- empty ink box
- ink pump deprimed (may occur if ink box is run to dry)
- no flow from ink box
- check in-line filter on box
- check flow from quick-connect on box
- ink pump not running (unlikely)
- use pump test in control panel to test; pump is very quiet so audible
detection is difficult. Remove enclosure and place a fingertip on the center pump
spindle, which can be felt to turn if pump when operating.
- check valve blocked (less likely, but possible)
- large filter blocked (unlikely)
- thermistor failure (fails to detect the presence of ink; can lead to an overfilling of
the printheads)
- headboard failure (fails to properly negotiate with the thermistors) (unlikely)
Air Vacuum / Pressure - The air system consists of these components:
- pressure pump
- a vacuum pump/sensor/regulator assembly (along with various fittings and tub-
ing, generally all replaced as an assembly)
- vacuum accumulator or vacuum reservoir
- tubing
- valve/manifold assembly at the carriage
The pressure pump is used only when servicing the printheads via the Purge
procedure. At any other time, the vacuum components are in operation to keep
the small (15 ml.) quantity of ink suspended in the printhead reservoir. The
valve/manifold assembly on the carriage opens and closes on command from the
5400 Technical Training Manual
MacDermid ColorSpan Confidential
Page 24 of 39
MacDermid, Inc. 11311 K-Tel Drive, Minnetonka, MN 55343
Phone: 952-944-9457 Fax: 952-944-8507
