Specifications

Appendix B
PF Motor Drive Circuit
The stepping motor that the printer uses to advance the paper can advance it by a
minimum of 1/360 inch. The motor is a 2-2 phase or l-2 phase, constant-voltage
drive type. P70 to P73 on the CPU are the phase control ports for the stepping
motor. PF motor phase data is output through these ports. Cl to C4 are turned on
and off within the PU1501 (IC3) based on the phase data sent from the CPU.
When the paper advance motor is running, the supply voltage to the PF motor coil is
+35 V. When the paper advance motor is not running and is in the hold state, the
supply voltage to the coil is +5 V. Switching between these two supply voltages
occurs at the CP terminal of the PU1501 (IC3) when the switch is turned on or off.
TMP90C041
pu1501
PF MOTOR
; - _ _ - - - - _ - - - _I
(IC21)
P70
Bl
P71
B2
P72
B3
P73
B4
E05A50
1 PFCOM PFCOM :
(ICll)
1
P3 .
BP
Data
CP
. .
0
Bus
HoM Current
1 Supply Circuit 1
Figure B-8. PF Motor Drive Circuit
Epson LQ-570+/1 070+ B-13