DOWNLOAD Sharp AL-1000 / AL-1010 (serv.man14) Service Manual ↓ Size: 246.22 KB | Pages: 25 in PDF or view online for FREE

PIN No.

Signal name

IN/OUT

Connected to

Description

250

/CPUWR

IN

CPU

CPU write signal

251

/CPURD

IN

CPU

CPU read signal

252

GND

Power

253

CPUCLK

IN

CPU

CPU system clock

254

GND

Power

255

TEST
PORT1

IN

AUTO SCAN
TEST

High: Normal Low: Test

256

/SCANST

IN

CPU (I/O)

Scanner process start signal

This circuit detects ON/OFF of power to control start/stop of each circuit. The 5V voltage of the main PWB is detected by the reset
IC to generate the reset signal.
When the power voltage reaches the specified level, the circuit operations are started. Before the power voltage falls below the
specified level, the circuit operations are stopped to prevent against malfunctions.

R265 R266

IC108D

C155

IC105

C156

C154

C190

To ASIC

Rest IC

AL-1000/1010

12-13

(1) Outline
The heater lamp control circuit detects the heat roller surface
temperature and converts in into a voltage level, which is in-
putted to the CPU analog input pin. 
The CPU converts the analog voltage into a digital signal level
and compares it with the set value of the simulation to turn
on/off the heater lamp according to the level, maintaining the
heat roller surface temperature at a constant level. 

5V

HLOUT(5-A4)

Thermostat

Heater lamp

HLOUT

PC2

TRC1

+24V

PR-

RY1

Selector

IC112  

ANo

IC110

CPU

PR

PR-

Driver

IC103

R112
120J1/4W

Q104

DTA143XKA

HL-

HL

Heat
roller

Thermistor

1

2

THOPEN   

AC  

Driver

IC114

AL-1000/1010

12-14

The lower the heat roller surface temperature is, the greater the
thermistor resistance is, and vise versa.
Therefore, the lower the heat roller surface temperature is, the
higher the thermistor terminal voltage is, and vise versa. The
thermistor terminal voltage is inputted to the CPU analog port.
The CPU controls ON/OFF of the heater lamp by this input volt-
age level.
[High temperature protect circuit in case of CPU hung up]
For IC119 3pin (reference voltage), +5V is divided by the resis-
tor.
The thermistor terminal voltage is inputted to IC119 2pin. 
When, therefore, the voltage at 2pin becomes lower than the
voltage at 3pin (when the heat roller temperature is about 220
C - 230˚C), IC119 1pin becomes HIGH, and the HL signal is
lowered to the GND level through IC114, stopping generation of
the heater lamp ON signal. (IC119 1pin is normal LOW.)

[When the heat roller surface temperature is lower than the
set level]
a. Since the thermistor terminal voltage is higher than the set

level, the HL signal from the CPU becomes HIGH. 

b. The HL signal is turned to be the HLOUT signal through

IC114 protect circuit, and inputted to the photo triac coupler
(PC2). 

c. 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, light-
ing the heater lamp.

[When the heat roller surface temperature is higher than
the set level]
a. Since the thermistor terminal voltage becomes lower than

the set value, the HL signal from the CPU becomes LOW.

b. The HL turns LOW, the PC2 turns OFF, the external triac

turns OFF, and the heater lamp turns OFF. 

[In case of the thermistor open]
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.

(1) Outline
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.

(2) Operation
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.

Internal circuit 

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. 

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

IC111

ASIC

IC114

TD62503F

X

Main motor
control circuit
(in main motor)

Selector

IC112

SIN2

5

14

CPU

IC110

MM

MM-

MMLD

LOAD

+24V

CPU

OUT PUT

LOAD

+24V

CPU

OUT PUT

R208
47KJ

R201
47KJ

2

9

1

5

+5V

IC101

TA7291S

IN1

IN2

GND

6

8

7

3

M

+

C201

10µF35V

TMa

TMb

ASIC

24V

TM

TM-

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)

AL-1000/1010

12-15

2

TDA

13

TDB

9

RSA

3

REF

A

14

REF

B

10

RSB

5

IN /A

8

IN A

16

IN/B 

17

IN B

7

VSA

12

VSB

1

OU

T A

6

OU

T A

11

OU

T B

18

OU

T B

4

GA

15

GB

IC118

SLA

7027MU

CPU

CP101

ICP

-N3
8(ROHM)

24V

C321

47µ35V

M

5V

C35

7

47µ

F

25V

R340

47K

J

C273

470

PF

R339

47K

J

R345

750

J

C257

7

470

PF

R297

R114

1J2W

R338

2.4K

J

R344

2.4K

J

R165

1J2W

C254

220

0p

C276

220

0PF

R296

620J

IC114

ASIC

R346

@@@@@@@@@@@@@@@

100J

Mirror motor

The mirror motor is a stepping motor, and it uses the IC118 and the constant current chopper control IC (SLA7027). For control, the
CPU outputs the drive signal to the IC118 to drive the mirror motor with 1-2 phase excitement. 

AL-1000/1010

12-16