Samsung SG626, SG628, BG626, BG678, SG676 Circuit Descriptions

6. Circuit Descriptions

1. Power circuit

WHT GRY

GRNREDBLK

L V T

CON1

BLK

BLU

(DC12V)

C107
470uF

25V

V12

(DC12V)

C109

104

+12

Vcc

(DC5V)

BD05-08

1N4004 X 4

1

FUSE2

250V 0.5A

1

3

3
5

5

7

1N4004 X 4

C103

BD01-04

7

HEAT-STICK

+

C

C106

1000uF

35V

7812

(MC7805)

IC02

HEAT-STICK

7812

(MC7812)

HEAT-STICK

7805

(MC7805AC)

+

IC03

ICO1 +

IC03

C

470uF

25V

104

+

Circuit used

+12

Voltage

(DC 12V)

Vcc (DC 5V)

V12 (DC 12V)

Relay Operation

Power around MICOM & Sensor Detector

LED Display & S/W Detector

The input AC voltage of DC-trans secondary registers 15V at CON1 between ①~③. The rectified
voltage passed through BD05 ~ 08 becomes DC 12V through volt age regulator MC7812(IC02). The
power(DC12V) is supplied to the relay operation power block. Then, DC 5V is genetatel and supplied
to the power around micom and sensor detector through 7805(I C03).
The rectified voltage passed through BD01~04 passes through 7812(IC01). Then, DC12V is supplied to
LED display and switch detector.

18 Samsung Electronics

2. Oscillator

30P

30P

Port

Oscillating Fr equency

Xin

Xout

±0.5% Error

3. Reset Circuit

R201

1K

KA7533

C203

1µF/25V

Port

x-tal

30

31

4.00MHz

4.00MHz

R202

29

10K

C202

104

Voltage

Xin

Xout

RESET

It is designed for clock generation and time
calculation for synchronizing transmission and
reception on the logic elements inside the MICOM.
If the X-TAL specification changes, MICOM may
make an error. The standard components should be
used.

When power is supplied to MICOM, reset circuit
initializes RAM and other parts on MICOM to
initialize all programs. Reset voltage maintains
“low” for hundreds of µsec comparing to MICOM
Vcc voltage when power is input. It also maintains
“high”(5V) during normal operation. But, when Vcc
drops to 3.3V, reset port becomes “low”.

Xin

Xout

4. Door S/W Detector

F-DOOR S/W

R-DOOR S/W

5V

5V

CON06

Vcc

R401(4.7K)

R403(4.7K)

R402

10K

R404

10K

C401

104

C402

104

7

8

Samsung Electronics 19

DOOR

F

Door Conditions

CLOSE

OPEN

Door S/W Contact

OPEN

CLOSE

MICOM

PIN NO

# 7

Micom Input Voltage

“LOW”

“HIGH”

CLOSE

R

OPEN

OPEN

CLOSE

“LOW”

# 8

“HIGH”

1) If door is open, door S/W contact is closed. Then MICOM receives “low” signal and detects
door open.

2) If door is closed, door S/W contact is open. Then MICOM receives “high” signal and detects
door close.

5. “V” Motor Position Detector(Reed S/W)

CON 02

REED S/W

7

6

5

Vcc

R405

4.7K

R406

10K

C403

104

43

1) The position of “V” motor for controlling the G.A–fuzzy of the temperature in the
refrigeration room is detected by the reed switch.

2) When MICOM Pin 43 changes ‘high’ to ‘low’ by the operation of fan, MICOM detects the
position of “V” motor.

20 Samsung Electronics