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Carriage Go (A)
The carriage go line is activated to start the
carriage oscillator. The carriage oscillator
furnishes pulses to run the carriage drive
circuits.
Stop Ribbon (A)
The stop ribbon line is activated if the printer
is idle for 5 seconds. When the signal is acti-
vated, the ribbon stops moving to prevent
smudging the paper.
Hammer Check 1-44,45-88,89-132 (P)
The hammer check lines determine if each
group has an odd number of hammers on.
They are used as input for the hammer pari-
ty check and the coil current check.
Activate Paper Clamps (A)
This signal energizes the upper and lower paper
clamps during printing. It is deactivated during
a spacing operation and when the printer is idle.
Carriage Advance (P)
The carriage go line activates the carriage ad-
vance digital control circuits. These circuits
generate the carriage advance pulses. Each
carriage advance pulse advances a shift register
pulse, which advances the print carriage motor
one increment or eight increments per line.
Therefore
J
eight carriage advance pulses
decrease the space count once per line. When
the space count reaches zero, the carriage oper-
ation is complete, which resets carriage go. The
carriage advance pulse is also used to detect
carriage sync check.
Home Pulse (P)
On the type belt there is a double space between
two of the timing marks. This space (missing
timing mark) generates the home pulse that
signals the start of the type set on the type belt.
The home pulse is used to synchronize the type
belt and the belt position counter (additional
information on page 4-83).
Throat Closed Switch (P)
This line sends the condition (open or closed)
of the print unit interlock switch to the attach-
ment. The switch must be closed to make the
pri nter ready.
Cover Closed Switch (P)
The cover must be closed to make the printer
ready.
Forms Sensed Switch (P)
This line indicates to the attachment whether
or not there are forms in the printer.
Printer Thermal Switch (P)
This line signals that the temperature in the
printer circuitry is too high. It turns on the TH
CH K light on the operator control panel in case of
overheating. The switch opens at 145° F ± 5° F
(63°C ± 3°C).
Belt Printer
2851pm
4-93
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