Pitney Bowes DM300c Service Manual page 43

3.4 Envelope/
Tape Transport
✍
TIP: See section 3.10
for DM475 differences
and specific theory.
DM300c/DM400c/DM475 Service Manual (SV61801 Rev. D)
Sequence of Operation (cont'd)
Sensor PS3 is used to re-
port jams or no paper con-
ditions. In the 3C00 only,
sensors PS2 and PS3 are
used for skew detection.
DM400c-DM475 software
does not detect skew and
do not use PS2.
PS3 also triggers the
postage debit request;
if that request is com-
pleted successfully within
110/120msec, the printing
process starts.
See Figure 3-12, right, for
the location of the mailing
machine sensors. The sen-
sor board to which the sen-
sors are mounted is shown
in Figure 3-42. Note that
the 6C00 does not have a
PS2 sensor mounted on its
sensor board.
Timing Inputs. Timing ref-
erence is provided by two
quadrature (two-channel) dis-
tance encoders each with a
resolution of 1651 pulses per
revolution or 0.088mm per pulse. The encoder output is used to determine
transport linear speed and adjust it based on envelope or tape position as
reported by the transport sensors.
As shown in Figure 3-13, next page, the autofeeder (AF) encoder is driven
by the AF main drive motor through a timing belt. The mailing machine en-
coder is mounted on the shaft of the segmented feed roller.
Operating Sequence—DM400c/DM450c. For the discussion that follows,
refer to the Transport Timing Diagram, Figure 3-15, and the DM400c Enve-
lope Print Diagrams, Figures 3-16 A and B.
1. When the user presses the START button and a stack is detected by
FS1, the system commands the purge motor to drive clockwise. This
action drives the print head cap and print head lock down and the print
head wiper up. The carriage drive motor then moves the carriage from
the home position (unblocking the carriage home sensor). The print
head is wiped and a mild purge initiated if necessary.
3 • Theory Of Operation
FS1
Figure 3-11 AutoFeeder Transport Sensors
PS1
Jam Lever
Sensor
Figure 3-12 Mailing Machine Transport Sensors
FS2: Mount-
ed on wall
behind roller
assembly
PS2
PS3
3-13