Olivetti ECR 6800, Руководство по обслуживанию

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4-22 Service Manual Y108540-8
Fig. 4-21
Input Voltage Signals for the Sample Drive Circuit
4.17 PRINTER CIRCUIT
Thermal printhead
The cash register printer's thermal printhead consists of heating elements that are driven by the head
drivers. The serial printing data input from the DAT IN pin is transferred to the shift register synchronously
with the CLK signal, then stored in the latch register with the timing of the LATCH signal.
Inputting the head activation signal activates the heating elements in accordance with the printing data
stored in the latch register.
Each 144-dot block for LTPC235 are printed.
Sensor
The cash register printer has a head-up sensor and a paper-end sensor.
Both signals normally output Low, but output High suring head-up or paper-end conditions.
This High signal goes through Nor-gate and changed Low, then it is input to P25 of the CPU (U9).
Excitation Sequence
As shown in the table of figure 4-22, the printer feeds paper in the normal direction when the motor is
excited in the order of step 1, step 2, step 3, step 4 step 1, step 2, by inputting the voltage signals shown
in figure 4-21.
Fig. 4-22 Excitation Sequence