Sharp R-231NW - K: Key Unit Test

R-231NW
8 - 5
If the key unit is defective.
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) 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 K) to
determine if control unit is faulty.
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) 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 fi gure appears.
f) A certain group of indicators do not light up.
g) The fi gure of all digits fl icker.
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.
[13] Procedure K : 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 re-
placed. About the other pads, the above method may be used.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
Pin NO. G1 Pin NO. G10
Key unit ribbon
cable
Key unit (Membrane Switch) front view
START
MINUTE PLUS
G10
G9
G8
G7
G6 G5 G4 G3 G2 G1
SOFTEN
COOK
STOP
CLEAR
TIMER
CLOCK
POWER
LEVEL
POPCORN
MELT 7 8 9
45
10
26
3
REHEAT WARMDEFORST
Service_R-231NW.indd 18Service_R-231NW.indd 18 6/24/09 3:56:45 PM6/24/09 3:56:45 PM