Daewoo Frs U20 Service Manual

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CONTENTS REMARKS 
4) Control Flow & Timing Chart
①Crushed Ice
②Cubed Ice
③Water 
Delay time : A = 500ms, B = 500ms, C = 2.0s, D = 5.0s
D.P SW 
Gear MotorD.P Lamp
D.P S/V 
(Flap)
D
A
A
C
    D.P SW 
Cube S/V
    D.P S/V
    (Flap)
Gear MotorD.P Lamp
A
C
A
A
B
D
D.P Lamp
D.P SW 
Water S/V
D
A
 from  ManualL 
						

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5-1. Power Circuit Diagram
5. CIRCUIT OPERATION
- Basic Model
5Vdc 14.5Vdc 12Vdc 310Vac 230Vdc VoltageCE6 CE4 CE3 CE1 MC1E D C B A
Parts
A
- Dispenser Model
B
D
C
E
AB
C
D
E
※Voltage of every part
※Caution : Since high voltage (DC310V) is maintained at the power terminal, please take a measure after more
than 3minutes have passed after removing power cords in the abnormal operation of a circuit.
 
						

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[F-sensor]
1) It senses the temperature of freezer compartment and control Comp., F-fan ON/OFF
2) How it works;
-19℃ -16℃ -11℃ Working Temp.
≒3.24V ≒9.32㏀ Low ON
≒2.73V ≒2.93V Sensing Voltage≒15.58㏀ ≒15.19㏀ ResistanceHigh OFF Mid OFF Working Point
[R-sensor]
1) It senses the temperature of refrigerator compartment and control R-fan ON/OFF
2) How it works;
3.2℃ 5.2℃ 7.7℃ Working Temp.
≒2.96V ≒23.33㏀ Low ON
≒2.72V ≒2.83V Sensing Voltage≒24.76㏀ ≒24.05㏀ ResistanceHigh OFF Mid OFF Working Point
[D-sensor]
1) It senses return point of defrosting heater.
2) How it works;
13℃ Working Temp.
≒3.08V ≒22.56㏀ Return point of defrosting heater
Sensing VoltageResistance Working Point
CONTENTS REMARKS 
5-2. Function of Each Sensor
- Dispenser Model
* In case temperature of refrigerator compartment is weak or insufficient  though comp.
and R-fan operate in normal way;
1) Cut J1 on the M-PCB, then temp. is lowered 1.5℃than [Mid OFF point]
2) Cut J1 and J2 on the M-PCB, then the temp, is lowered 3℃.IC1
(MICOM)
Compensation of 
R-sensor ON/OFF temp.
A
C
B
 
						

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CONTENTS REMARKS 
- Dispenser Model
[F-sensor (A)]
1) It senses the temperature of freezer compartment and control Comp., F-fan ON/OFF
2) How it works;
-19℃ -16℃ -11℃ Working Temp.
≒3.24V ≒9.32㏀ Low ON
≒2.73V ≒2.93V Sensing Voltage≒15.58㏀ ≒15.19㏀ ResistanceHigh OFF Mid OFF Working Point
[R-sensor (B)]
1) It senses the temperature of refrigerator compartment and control R-fan ON/OFF
2) How it works;
3.2℃ 5.2℃ 7.7℃ Working Temp.
≒2.96V ≒23.33㏀ Low ON
≒2.72V ≒2.83V Sensing Voltage≒24.76㏀ ≒24.05㏀ ResistanceHigh OFF Mid OFF Working Point
[D-sensor (C)]
1) It senses return point of defrosting heater.
2) How it works;
13℃ Working Temp.
≒3.08V ≒22.56㏀ Return point of defrosting heater
Sensing VoltageResistance Working Point
* In case temperature of refrigerator compartment is weak or insufficient,
though comp. and R-fan operate in normal way;
1) Cut J18 on the M-PCB, then temp. is lowered 1.5℃than [Mid OFF point]
2) Cut J18 and J19 on the M-PCB, then the temp, is lowered 3 ℃IC1
(MICOM)
Compensation of 
R-sensor ON/OFF temp.
A
B
C
D
 
						

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1. Circuit Diagram
#14≒12V #12≒12V #10≒12V
#14≒0.7V #12≒0.7V #10≒0.7V
IC7 #3≒0V #3≒5.0V Relay 3 Louver HeaterOFF Condition ON Condition
#5≒0V #5≒5.0V Relay 5 D-HeaterRelay 1 Control Mode
Method
IC7IC ULN2004 
Output pin
#1≒5.0V MICOM Port
#1≒0V MICOM Port
CompIC ULN2004
Output pin Control
CONTENTS REMARKS 
5-3. Relay Function
- Basic Model
2. How it works;
IC1
(MICOM)
Comp
D-Heater
Louver HeaterD-Heater Louver Heater Comp R-Lamp F-Lamp 
 
						

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1. Circuit Diagram
CONTENTS REMARKS 
- Dispenser Model
2. How it works;
#15≒12V #14≒12V #13≒12V #12≒12V #11≒12V #10≒12V #15≒12V #14≒12V #13≒12V #12≒12V #11≒12V #10≒12V
#15≒0.7V #14≒0.7V #13≒0.7V #12≒0.7V #11≒0.7V #10≒0.7V #15≒0.7V #14≒0.7V #13≒0.7V #12≒0.7V #11≒0.7V #10≒0.7VOFF Condition ON Condition
#3≒0V #3≒5.0V Relay 3 H/B Heater
IC8 #7≒0V
IC8 #7≒5.0V Relay 7 Water (Dispenser)#6≒0V #6≒5.0V Relay 6 Water (Ice)#5
≒0V #5≒5.0V Relay 5 Dispenser-Solenoid#4≒0V #4≒5.0V Relay 4 Dispenser-Lamp
#9≒0V #9≒5.0V Relay 9 D-Heater#8≒0V #8≒5.0V Relay 8 Geared-Motor
#10≒0V #10≒5.0V Relay 10 F-Lamp
#11≒0V #11≒5.0V Relay 11 Cube-Solenoid
Relay 12Relay 2 Relay 1 Control Mode
Method
IC7IC ULN2004 
Output pin
#12≒5.0V #2≒5.0V #1≒5.0V MICOM Port
#12≒0V #2≒0V #1≒0V MICOM Port
IC7 CompIC ULN2004
Output pin
Water Pipe HeaterR-LampControl
IC1
(MICOM)
D-Heater Louver Heater Comp R-Lamp F-Lamp 
 
						

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5-4. Fan Function
- Basic Model
- Dispenser Model
- Vref is the reference voltage for the adjustment of the output voltage by the voltage
distribution of Vs (Maximum output voltage), and the output voltage applied to the fan
is determined by the PWM control using the software. 2. Explanation for the operation
* TA7291P is the drive IC for the only DC motor, and used for control of the fan motor
* One input and output is used for the control of the fan motor
Motor IC No.2 Pin
(R:MT2/F:MT3/C:MT1) Motor IC No.5 Pin
(R:MT2/F:MT3/C:MT1)
Low High Output
Stop Low13V HighRemark Input
1.  Circuit Diagram
 
						

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6-1. Wiring Diagram
6. DIAGRAM
- Basic Model
 
						

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- Dispenser Model
 
						

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6-2. Circuit Diagram of Main PCB
- Basic Model