Swecoin TTP 101, Service Manual

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0102 TTP 101 Kiosk Printer Sub-system – Service Manual 13
The combined TOF (Top-Of-Form) and paper-out sensor is used to verify that paper is
loaded and to position the paper correctly in relation to TOF marks pre-printed at the back
of the paper. See TTP 101 Installation Manual for details about this function.
3.1.2 Cutting
When a cut command has been issued, the cutter motor (DC motor) first turns in one
direction to move the knife upward to perform the cutting. The knife then starts moving
down and, when it reaches its home position at the bottom, the knife actuates the cutter-
home sensor. The mechanism is then forced to a quick stop by a momentary polarity
change of the supply voltage to the cutter motor.
3.2 Electronics
Please also refer to block diagram in figure 7 and to logic diagrams in Chapter 6.
3.2.1 Control board SWC-842 and SWC-642
These two boards differ in that SWC-842 has integrated interface connectors, an
improved RS232 driver, and interference suppression filters on the interface signals.
RESET CIRCUIT
See logic diagram sheet 2, pos. B3 and sheet 1, pos. C6.
The microprocessor (U1) is reset at power-ON by the RESET signal. Capacitor C29
delays the reset until the +5V has reached the appropriate voltage level. The control board
can also be reset from the host by means of the /INIT signal (J16/18).
THERMISTOR CIRCUIT
See logic diagram sheet 2, pos. A6.
A thermistor is mounted on the printhead heatsink. When measuring the printhead
temperature, the microprocessor temporarily sets signal THERMISTOR low through an
NPN transistor inside the processor chip. This discharges capacitor C7. The time it takes
to recharge the capacitor through the thermistor, which will generate the TEMP interrupt,
also determines the printhead temperature.
PRINTHEAD STROBE GENERATING CIRCUITS
See logic diagram sheet 2, pos. A4.
The order in which +5 V and +24 V are established on the printer control board is
essential. The + 5 V must be established before the + 24 V drive voltage is brought to the
board (and vice versa at power-off). Otherwise, there is a risk of damaging both the
printer control board and the thermal print head . Capacitor C6 and Zener diode Z1
regulates the supply voltage to U12.
PAPER-OUT SENSOR (ONLY SWC-642)
A solder jumper between J16/19 and J16/20 connects pole J8/3 (PO-SENSE) to bus latch
U7/16 (PO-SENSE-IN). Connector poles J16/19 and J16/20 must not be used .