Pf Motor Driver Cimuit; Figure 2-26. Measurement Sequence - Epson C117001-N - DFX 5000+ B/W Dot-matrix Printer Service Manual

Operating Principles
transfer direction
3
1
2.3.5 PF Motor Driver Circuit
Stepping motor driver SLA7026 (IC1l) drives the PF motor. Figure 2-27 shows the PF motor driver
circuit block diagram, and Table 2-6 provides the PF motor specifications.
Gate Array
E05A87 (IC7)
CPU TMP96C141
I
The motor pulse switching signals are transmitted from CPU ports PGOO to PG03. The PF motor is
controlled using open-loop phase switching based on the specified time data, and the phase
driving method is 1-2 phase excitation. (When the PF motor is held, the phase driving method is 2
phase excitation.) The CPU selects the most suitable driving mode from the modes below
according to conditions such as the paper feed step number and the pull tractor condition.
Each phase switching FET in driver IC1l is an open collector. When the phase switching data is
HIGH, the motor is turned on. The PFA port of the gate array monitors the phase A signal of the
PF motor and checks whether it is operating normally. The PFA port is used as the WDT (watch
dog timer). If PF motor operation is abnormal, the gate array outputs the RSTOUT (reset request)
signal to the CPU and the +5 V system reset IC (IC9).
2-30

Figure 2-26. Measurement Sequence

Ref. voltage
setting circuit (Q23)
I
A
Figure 2-27. PF Motor Driver Circuit
Right ~ Left
3
1
I
-A
B
-B
IN-B
4.7 VDc
PF B
PF D
Rev. A