Service manual

3 • Theory Of Operation
DM300c/DM400c/DM475 Service Manual (SV61801 Rev. D)
3-25
• The communication protocol to the print head is not standard.
• The print head functions only with Pitney Bowes-managed equipment.
• There is an enciphered link between the PSD (iButton) and the carriage
board.
The following error messages are associated with the print head:
• Print Head Fault—The system detected a print head fault. Power cycle
the machine. If the problem persists, install a new print head.
• No Print Head Detected—The system failed to detect the print head.
Install a print head. The system can still run in seal-only mode.
The carriage board is connected by a flexible ribbon cable to J127 on the
main logic board. The print head is held against the connector pins on the
carriage board.
Carriage
Assembly
The print
carriage as-
sembly moves
the print head
and ink tank
from the home
to the print
position and
back again.
The print car-
riage also has a cleaning pad
mounted on its back side. As
the carriage passes over the
wiper blade, the cleaning pad
wipes off the wiper blade.
The carrier holds the print
head and ink tank. It rides on
two rails mounted between
the chassis’ front and rear
plates and is driven by the
carriage drive stepper mo-
tor through a timing belt. The
timing belt tensioner is not
self-setting (not spring-load-
ed). Belt tension is factory set
at 2.2 lbs.
As explained below, the
home position is detected by a sensor mounted on the purge unit. The car-
riage drive motor connects to the main logic board at J118.
Figure 3-24 Carriage Assembly in Home Position
Carriage Drive Belt
Carriage Drive Motor
Print head
Outer Rail
Inner Rail
Ink Tank
Carriage
Figure 3-25 Carriage, Removed from Machine,
Bottom View
Print head
Wiper
Cleaner
3.5 Ink System
Print Head and Carriage Board (cont’d)