Samsung b25, S25, B24, S26, S27 Circuit Descriptions

...

Terminal oscillation frequency

X in(#30)

X out(#31)

4MHz

8-1. Power supply part

About AC 9V, pressed at 2nd side of LVT(LOW Volt Transformer), is suspended between CN10

~ and DC 5V is made through constant-voltage IC (KA7805) rectified by Rectifier Diode. And, about AC 17V is suspended between CN10 ~ and DC 12V is made through constant-voltage IC(KA7812).

8. Circuit operation theory

8-2. Power generator circuit part

This is a power generator circuit part to generate synchronous CLOCK for information transfer of MICOM internal degauss and calculate time. On change of spec. of RESONATOR, normal operation cannot be performed from the result of change of TIMMING system in MICOM.

8-3. RESET circuit part

RESET circuit is to operate overall PROGRAM in the primary state by initializing several parts including RAM in the internal of MICOM when power is supplied to MICOM as a result of power input or instant suspension of electric supply. When power is supplied, voltage at RESET Terminal becomes scores of

ÒLowÓstate, when compared to the voltage of Vcc (DC 5V) of MICOM. On the general operation

state,ÓHighÓ (Vcc voltage) state is maintained.

Voltage Circuit used

Vcc Power supply for MICOM

(DC 5V) and peripheral circuit

V12 Power supply to operate RELAY,

(DC 12V) EJECT MOTOR, DISPLAY

Terminal oscillation frequency

Vcc

RESET

DC 5V

GRY

RED

BLK

BLU

8-4. DOOR S/W sensing circuit

DOOR OPEN/CLOSE of F-room sensing is performed by connecting of CN30 to GROUND, supplying Vcc (DC 5V) to through resistance R404 (4.7 ) and supplying ÒLowÓ (0V) / ÓHighÓ(5V) to MICOM by DOOR OPEN/CLOSE of F-room. DOOR OPEN/CLOSE of R-room sensing is performed by connecting of CN31 to GROUND, supplying Vcc (DC 5V) to through resistance R403 (4.7 ) and supplying ÒLowÓ (0V) / ÓHighÓ(5V) to MICOM by DOOR OPEN/CLOSE of R-room. If there is any problem in DOOR S/W, Fan in the relevant room will not work and alarm function will operate. So, DOOR S/W should be checked if there is any problem on A/S. For FAN in the relevant room will stop on DOOR OPEN, if there is any problem in the contact point of S/W, MICOM will judge that DOOR is opened and stop FAN operation, although DOOR is closed.

8-5. Temperature sensing circuit

SENSOR works on the basis of the characteristics of THERMISTOR with temperature coefficient of negative resistance that resistance value decrease when temperature is High and resistance value increase when temperature is low. R306 ~ R310 and C302 ~ C306 are parts to prevent NOISE. They have no relation with temperature sensing. In case of F-SENSOR, when the voltage inputted to MICOM is considered to be Vf, Vf is (Rth Vcc) /(R303 + Rth). In this equation, Rth is the resistance value of THERMISTOR corresponding to temperature. See the conversion table of the resistance and voltage of sensor according to the temperature in the Reference No. 8 of this manual. Use the table on A/S because MICOM Terminal voltage is also described in the table.

Terminal Voltage MICOM

F-room

On DOOR CLOSE

On DOOR OPEN

5V (HIGH)

0V(LOW)

R-room

On DOOR CLOSE

On DOOR OPEN

0V (LOW)

5V(HIGH)

MICOM Terminal Voltage

PIN #58 (F-SENSOR)

PIN #57 (R-EVA-SENSOR)

PIN #56 (R-SENSOR)

PIN #59 (F-EVA-SENSOR)

PIN #60 (AMBIENT-SENSOR)

Voltage in

MICOM

Terminal is

changed

according to

temperature.

AMBIENT

8-6. KEY SCAN and DISPLAY circuit part

1. Running of KEY SCAN and DISPLAY

As shown in the following waveform of each part, ÒHighÓ output is sent in turn from MICOM PIN

#3 #4 #5 #6 #7 for 2 msec at 10msec interval using five Terminal of MICOM NO #3, 4, 5, 6, and 7.

This signal appears at OUTPUT Terminal through INPUT Terminal of IC05 (UDN2981 or UPA2981C).

At this time, PEAK TO PEAK voltage of square-wave is about 11 V (DC RMS 1.5 V) and output waveform

is as follows.

2. KEY SCAN

When GRID #1 waveform is outputted, this signal is supplied to the button for temperature-setting of freezing room through resistance 10 . At this time, when you push button for freezing room, the signal becomes decreased by R506 (6.8 ) and about 4.5 V of PEAK TO PEAK voltage is approved to MICOM. After supply of about 4.5 V of PEAK TO PEAK voltage to MICOM, MICOM can judge that GRID #1 waveform is inputted and then, change the temperature-setting for freezing room. Like this way, each GRID waveform is perceived.

POWER-

FREEZING

POWER-FREEZING

POWER- REFRIGERATING

POWER-REFRIGERATING

F, R ROOM

DEODORIZATION

DOOR-SECURING

or CUBE

COLDER-HUMIDITY

or CRUSH

Door-Securing

ONor

CRUSHED/CUBE

POWER REF

POWER FRE

REFRIGERATOR ROOM SETTING

FREEZER ROOM SETTING

Door-Securing

OFF or

LIGHT ON/OFF

RED-RED BLU-BLUE ORG-ORANGE BRN-BROWN PNK-PINK GRY-GRAY WHT-WHITE YEL-YELLOW BLK-BLACK PRP-PURPLE W/BLKWHITE/BLACK S/BLUSKY BLUE

REFERRENCE

8-7. LOAD OPERATION circuit part

When ÒHighÓ signal is supplied to INPUT of IC03 (ULN2003A) at MICOM PIN NO #22 (P15), IC comes to be turned on. At this time, if V12 (DC 12V) supplied to the lower COIL of COMP RELAY runs into GROUND through OUTPUT of IC03, magnetic field will occur at CORE and then make contact point ON. This approves 220 V to COMP LOAD to make COMP ON and, if MICOM PIN NO #22 becomes ÒLowÓ state, IC comes to be TURN OFF state to make current not running to COMP RELAY COIL, to make RELAY contact point OFF state, and then, finally to stop COMP.

1. Explanation of co-operation of COMP and F, R-Defroster HEATER

RED

COMP load

F-Defroster Heater

R-Defroster Heater

GRY

R-Defroster

Heater

F-Defroster

Heater

RED-RED BLU-BLUE ORG-ORANGE BRN-BROWN PNK-PINK GRY-GRAY WHT-WHITE YEL-YELLOW BLK-BLACK PRP-PURPLE W/BLKWHITE/BLACK S/BLUSKY BLUE

REFERRENCE

WHT

PRP

BRN

GRY

YEL

RED

W-BLK

BLU

ORG

WHT

RED

L-BLU

BLK

F-Defroster Heater

F-ROOM LAMP

Circulation Fan

DISPENSER HEATER

DISPENSER LIGHT

SOLENOID-VALVE

Circulation Fan

HOME BAR HEATER

Compressor

R-Defroster Heater

COMP-FAN for basic model

GRN

RED

GRY

RED

GRY

BLK

PRP

Temperature Fuse

RED

ORG

BLU

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