Sharp R-230HW Service Manual - Page 17

Control Unit.

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TEST PROCEDURES R-203HW R-220HW R-230HW PROCEDURE LETTER COMPONENT TEST 4) Replace the key unit. 5) Reconnect all leads removed from components during testing. 6) Re-install the outer case (cabinet). 7) Reconnect the power supply cord after the outer case is installed. 8) Run the oven and check all functions. 2. Control Unit. The following symptoms indicate a defective control unit. Before replacing the control unit, perform the Key unit test (Procedure J) to determine if control unit is faulty. 2-1 In connection with pads. a) When touching the pads, a certain group of pads do not produce a signal. b) When touching the pads, no pads produce a signal. 2-2 In connection with indicators a) At a certain digit, all or some segments do not light up. b) At a certain digit, brightness is low. c) Only one indicator does not light. d) The corresponding segments of all digits do not light up; or they continue to light up. e) Wrong figure appears. f) A certain group of indicators do not light up. g) The figure of all digits flicker. 2-3 Other possible problems caused by defective control unit. a) Buzzer does not sound or continues to sound. b) Clock does not operate properly. c) Cooking is not possible. When testing is completed, 1) Disconnect the power supply cord and then remove outer case. 2) Open the door and block it open. 3) Discharge high voltage capacitor. 4) Reconnect all leads removed from components during testing. 5) Re-install the outer case (cabinet). 6) Reconnect the power supply cord after the outer case is installed. 7) Run the oven and check all functions. J KEY UNIT TEST 1. Disconnect the power supply cord, and then remove outer case. 2. Open the door and block it open. 3. Discharge high voltage capacitor. 4. Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit, check the circuit between the pins of the key unit that correspond to the STOP/CLEAR pad. When the pad is pressed, the ohmmeter should indicate short circuit. When the pad is released, the ohmmeter should indicate open circuit. If incorrect readings are obtained, the key unit is faulty and must be replaced. About the other pads, the above method may be used. 5. Reconnect all leads removed from components during testing. G 1 G 2 G 3 G 4 G 5 G 6 6. Re-install the outer case (cabinet). 7. Reconnect the power supply cord after G 7 the outer case is installed. 8. Run the oven and check all functions. G 8 6 2 COOK MINUTE PLUS 3 5 4 POPCORN POWER LEVEL Pin NO. G1 Pin NO. G10 G 9 G10 Key unit ribbon cable TIMER CLOCK 0 9 8 1 DEFROST STOP CLEAR 7 REHEAT START Key unit (Membrane Switch) front view 15

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15
R-203HW
R-220HW
R-230HW
4)
Replace the key unit.
5)
Reconnect all leads removed from components during testing.
6)
Re-install the outer case (cabinet).
7)
Reconnect the power supply cord after the outer case is installed.
8)
Run the oven and check all functions.
2.
Control Unit.
The following symptoms
indicate a defective control unit.
Before replacing the control unit, perform
the Key unit test (Procedure J) to determine if control unit is faulty.
2-1
In connection with pads.
a) When touching the pads, a certain group of pads do not produce a signal.
b) When touching the pads, no pads produce a signal.
2-2
In connection with indicators
a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f)
A certain group of indicators do not light up.
g) The figure of all digits flicker.
2-3
Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
When testing is completed,
1)
Disconnect the power supply cord and then remove outer case.
2)
Open the door and block it open.
3)
Discharge high voltage capacitor.
4)
Reconnect all leads removed from components during testing.
5)
Re-install the outer case (cabinet).
6)
Reconnect the power supply cord after the outer case is installed.
7)
Run the oven and check all functions.
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
J
KEY UNIT TEST
1.
Disconnect the power supply cord, and then remove outer case.
2.
Open the door and block it open.
3.
Discharge high voltage capacitor.
4.
Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit, check the
circuit between the pins of the key unit that correspond to the STOP/CLEAR pad. When the pad is
pressed, the ohmmeter should indicate short circuit. When the pad is released, the ohmmeter should
indicate open circuit. If incorrect readings are obtained, the key unit is faulty and must be replaced.
About the other pads, the above method may be used.
5. Reconnect all leads removed from
components during testing.
6.
Re-install the outer case (cabinet).
7.
Reconnect the power supply cord after
the outer case is installed.
8.
Run the oven and check all functions.
1
2
3
4
5
6
7
8
9
0
POWER
LEVEL
MINUTE
PLUS
COOK
DEFROST
POPCORN
REHEAT
START
TIMER
CLOCK
G 1
G 2
G 3
G 4
G 5
G 6
G 7
G 8
G 9
G10
STOP
CLEAR
Pin
NO. G1
Pin
NO. G10
Key unit ribbon cable
Key unit (Membrane Switch) front view