Panasonic KX-FT21BX, Service Manual

Page: 151 / 206

CIRCUIT OPERATIONS
- 125 -
KX-FT21LA
(RECEPTION)
TRANSMISSION
MOTOR
T2
T3
T4
T5
152
151
150
149
11
4
3
2
1
5
12
13
14
6
T0 153
R64
R63
5
4
3
+24V
+5V
Q7
Q14
D2
IC7
GATE ARRAY
IC4
9
D3 D4
CN3
4-4. STEPPING MOTOR DRIVE CIRCUIT
(1) Function
One individual stepping motor is used for transmission and reception. It feeds the document or recording paper
synchronized for reading or printing.
(2) Circuit Operation
During motor drive, gate array IC1 pin 153 becomes a high level, and Q14 and Q7 go ON as a result. +24 V is supplied to
the motor coil.
Stepping pulses are output from gate array IC1, causing driver IC7 to go ON. The motor coil is energized sequentially in
2 phase increments or 1-2 phase increments, which causes a 1-step rotation. A 1-step rotation is 0.13mm of recording
paper or document paper.
The timing chart is below.
Timing Chart (2 Phase)
Copy
FAX
Function
Mode
Drive Phase
Pattern
Speed
Fine/Half Tone
Super Fine
STD
Fine/Half Tone
Super Fine
Paper Feed
1-2
1-2
2
1-2
1-2
1-2
217 pps
108.5 pps
217 pps
217 pps
108.5 pps
434 pps
Stepping Motor Phase Pattern
1-2. Phase (Asic T2-T5, output)
Circuit Diagram
T2
T3
T4
T5
T2
T3
T4
T5
When the motor is OFF, gate array IC1 pin 153 becomes a low level and Q14 and Q7 also turns OFF. Instead of +24V, +5V
is supplied through D2 so that the motor is held in place.