DOWNLOAD Sharp AL-1551 (serv.man4) Service Manual ↓ Size: 12.62 MB | Pages: 126 in PDF or view online for FREE

AL-1551 ELECTRICAL SECTION 12-12

For IC119 3pin (reference voltage), +5V is divided by the resistor.

The thermistor terminal voltage is inputted to IC119 2pin.
When, the voltage at 2pin becomes lower than the voltage at 3pin (when

the heat roller temperature is about 220 - 230°C), IC119 1pin becomes

HIGH, and the HL signal is lowered to the GND potential through IC114,
stopping generation of the heater lamp ON signal. (IC119 1pin is normal

LOW.)

1) Since the thermistor terminal voltage is higher than the set level, the

HL signal from the CPU becomes HIGH.

2) The HL signal is turned to be the HLOUT signal through IC114

protect circuit, and inputted to the photo triac coupler (PC2).

3) When the internal triac turns on, a pulse is applied to the gate of the

external triac. Consequently a current flow from the power source

through the heater lamp to the triac, lighting the heater lamp.

1) Since the thermistor terminal voltage becomes lower than the set

value, the HL signal from the CPU becomes LOW.

2) The HL turns LOW, the PC2 turns OFF, the external triac turns OFF,

and the heater lamp turns OFF.

The voltage at IC119 6pin over the voltage at 5pin to drive the output

THOPEN at 7pin to LOW. This is passed through the selector to the CPU

and the trouble code "H2" is displayed.

Since the control signal of each load outputted from the CPU cannot

drive the load directly, it is passed through the driver IC to the load.

The driver circuit forms a Darlington circuit with transistors. Therefore a

large drive current is obtained from a small current (CPU output current).
When the driver input voltage is HIGH (+5V), the transistor turns ON to

flow a current in the arrow direction, operating the load. When the driver

is ON, the driver output terminal voltage is 0V.

The IC101 is the motor control IC, which generates the pseudo AC

waveform with the pulse signals (TM, TM-) outputted from ASIC, driving
the toner supply motor.

The main motor is driven by the MM signal from ASIC. While the main

motor is rotating, the MM signal is driven to HIGH and passed through

IC114 to the control circuit in the main motor to
rotate the main motor. The MMLD signal is kept HIGH until the main

motor speed reaches the specified rpm, and passed through the selector

to the CPU.

LOAD

+24V

CPU

OUT PUT

LOAD

+24V

CPU

OUT PUT

M

ASIC

TM

TM-

R204
47KJ

R208
47KJ

IC101

TA7291S

VDD

2

IN1

9

IN2

1

VSS

5

OUT2 3

OUT1 7

VCC2 8

VCC1 6

C219

22000p

R205
47KJ

R209
4.7KJ

C105
10u 35V

+

D101 1SS133

D103

1SS133

R201
4.7KJ1/4W

C205

2200p

C104

0.47u 50V

+

Q202

DTC114EKA

1

2

3

Q201

2SA1036K

B1

E1

C1

5V

24V

TMb

TMa

/PWOFF(1-C1)

2

8

9

1

5

6

7

3

M

REG

GND

+5V

+24V

TMa

TMb

+24V

TMa

TMb

4pin is NC pin.

Protection circuit
(Heat insulation)

3
4
5
6
7
8

1

IN1

2

IN2
IN3
IN4
IN5
IN6
IN7
GND

14
13
12
11
10
9

16

OUT1

15

OUT2
OUT3
OUT4
OUT5
OUT6
OUT7

COM

ASIC

IC109

TD62503F

X

Main motor
control circuit
(in main motor)

Selector

IC203

SIN2

5

14

CPU

IC108

MM

MM-

MMLD

      !"#$%&

AL-1551 ELECTRICAL SECTION 12-13

The mirror motor is a stepping motor. Its driver is IC113 constant-current chopper control IC (SLA7024). For control, the CPU outputs a drive signal to

IC113 to drive the mirror motor by 1-2 phase excitement.
The SPF motor and the mirror motor are switched with relays RY1 and RY2. The switching signal is SMSEL-. When SMSEL- is LOW, a current flows

through the SPF motor. When it is HIGH, a current flows through the mirror motor.

The duplex motor is a stepping motor. Its driver is IC111 darlington-sink transistor driver IC (TD62064AP). For control, the CPU outputs a drive signal to

IC111 to drive the duplex motor by 1-2 phase excitement.

M

24V

24V-mir

RY102

G5V-2(OMRON)

RY101

G5V-2(OMRON)

M

ULN2003

/SMSEL

SPF motor

R362

R363

C453

C454

R309

IC113

MTD1361/F

CrA

23

CrB

20

RsA

3

VrefA

24

VrefB

19

RsB

12

In /A

26

In A

27

In /B

17

In B

16

Vmm

22

OUT /A 1
OUT A 4
OUT /B 14
OUT B 11

PG

15

PG

28

(1-C4) DMT0

(1-C4) DMT1

(1-C4) DMT2

(1-C4) DMT3

R286    2.2KJ         3

R285     2.2KJ         6

R278     2.2KJ        11

R279     2.2KJ        14

4

10

5

12

15

13

I1     O1
NC
NC
I2     O2
NC
I3     O3
NC
NC
I4     O4
NC

GND COM
GND COM

IC111

TD62064AF

2

7

9

16

D123
MTZJ22B

Duplex Motor

M

CP101

ICP-N38

24V1

1
8

 '     !"#$%&

AL-1551 ELECTRICAL SECTION 12-14

The power circuit is composed of the main section, the high voltage circuit, the FW signal section, and the heater lamp drive circuit.
The main section directly rectifies the AC power current and switch-converts with the DC/DC convertor, and rectifies again and smoothes to form each

DC power.

In the high voltage circuit section, the 24V output of the main section is switch-converted by the DC/DC convertor and rectified and smoothed to form
the high voltage output.

The FW signal section fullwave-rectifies the AC power to supply signal output at the timing of 0V.

Noise filter

ACin

Invertor
circuit

Main section

MC
High voltage
transformer
T101

High voltage
section

FW control section

Heater lamp drive
circuit section

Heater lamp output

3.3V

5V

12V

24V

MC

DV BIAS

Rectifying/
smoothing

BIAS    

GRID

GRID L

MC IN

TC

BC

TC IN

FW

HL

/PR 

Control

Rectifying/
smoothing

Transformer
T1

Rectifying/
smoothing

Series
regulator

Rectifying/
smoothing

Series
regulator

Invertor

Invertor

TC
High voltage
transformer
T102

Series
regulator

Dividing
circuit

Full-wave
rectifying

Series
regulator

Series
regulator

PC1

PC3

PC2

RY1

 (     !"#$%&

AL-1551 ELECTRICAL SECTION 12-15

The noise filter circuit of the DC power is composed of L and C as shown
in the figure below. It reduces normal mode noises and common mode

noises which come from and go to the AC line.

The normal mode noises are noises which are generated in the AC line
or the output line and are attenuated by C4B and C3. The common mode

noises are noise voltages generated between the AC line and GND, and

are attenuated by L1 and L2. The noise composition is bypassed to GND
through C4 and C5. 

The AC voltage of 50(60)Hz is full-wave rectified by the rectifying diode
DB1 and smoothed by the smoothing capacitor C6.

TH1 is the power thermistor which limits a rush current flowing to C6.

The DC voltage from the rectifying/smoothing circuit is supplied to the
secondary side of transformer T1 by switching operation of FET Q1.

For switching, the RCC (Ringing Choke Convertor) system is employed.

FET Q1 is turned on by the starting resistors R20 and R1 to generate a
voltage between terminals 4 and 6 of transformer T1 and between

terminals 2 and 3 simultaneously. Then a voltage is applied to the gate of

FET Q1 to oscillate high frequency.
The actual line in the circuit diagram shows the current to turn ON FET

Q1, and the dotted line shows the current loop through which the energy

accumulated in the transformer is discharged when FET Q1 is turned
OFF.

Voltage across Q1 drain and source (VDS)

Q1 drain current (ID)

 )     !"#$%&