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Theory
Autocompensator operation
The autocompensator is a paper pick device that generates its own normal force. This force
generation is inherent in the fundamental design of the pick arm. If light media is used, it picks very
gently. If a heavy media is used, it picks very aggressively. No customer adjustments are necessary,
therefore no special trays are needed for card stock or labels. The gearing in the arm is designed so
the input torque from the motor produces a movement about the pivot of the arm. This movement
produces a downward force at the pick rolls. The friction between the pick roll and the paper
produces a frictional locking condition. If the paper is physically held and not allowed to feed, then the
motor stalls. Slippage between the roll and the paper is theoretically impossible. When the motor is
energized, the pick rolls are driven down into the stack, increasing the normal force and drive force
until the bending strength of the paper is overcome and the paper bends and moves up the dam.
Once this critical threshold is achieved, the normal force remains at a level just high enough to
reliably feed the paper. Rather than having a fixed spring force for feeding all weights of paper like the
D-roll, this device has its own mechanical logic for producing only enough pick energy to feed a single
sheet of paper regardless of its stiffness. High normal force is one of the most significant contributors
to double feeding paper. The pick arm is counterbalanced by an extension spring located on the pick
arm to reduce weight in the rest state. This spring is factory set to exert no more than ten to fifteen
grams on the stack. This is as light as can be realistically set and always guarantee there is some
force to start the autocompensating phenomena. This spring is not to be considered an adjustment
for feeding problems unless it is obvious that the pick arm cannot fall all the way down to the bottom
of the tray or has come loose. Poor gear efficiency can cause the arm to generate higher normal
forces. If the pick assembly is noisy, replacement may be required. The arm must pivot freely through
its full range of motion. On 500-sheet trays there are wrap springs located on the pivot arbors of the
arm. These springs help prevent the arm from bouncing. If the arm appears to be binding or sticky
near the bottom of the tray, these springs may be the problem. Reducing the tension on the
counterbalance spring may be used as a temporary fix to get additional weight at the bottom, until the
pick assembly can be replaced. However, the counterbalance spring is not to be considered an
adjustment for feeding problems.
Autoconnect system, paper tray options, envelope feeder—electrical
Autoconnect cabling and connectors
The printer options make electrical connection automatically, requiring no external cables when the
option is mechanically installed under the printer. Communication between the option and the base
printer stops when you remove an option. The printer no longer recognizes the option and deletes
associated messages. Each installed option below the base printer provides an electrical
autoconnect to the option attached below it. We do not recommend to attach or "Hot Plug" any
options with the base printer power turned on.
Duplex Option
The duplex option interface is a six pin autoconnector that provides a +24 V dc, +24 V dc return,
serial interface transmit signal, serial interface receive signal, and two ground pins. The duplex option
receives the +24 V dc from the base printer for the duplex motors and also converts the voltage to
+5 V dc for duplex electronics.
4060-xxx
3-21
Diagnostic aids
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