Service manual

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3 • Theory Of Operation

DM300c/DM400c/DM475 Service Manual (SV61801 Rev. D)

3-13

Figure 3-12 Mailing Machine Transport Sensors

PS1 PS3

PS2

Jam Lever

Sensor

Figure 3-11 AutoFeeder Transport Sensors

FS1

FS2: Mount-

ed on wall

behind roller

assembly

3.4 Envelope/

Tape Transport

Sequence of Operation (cont’d)

✍

TIP: See section 3.10

for DM475 differences

and specific theory.

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.