17
R-426HS
R-426HK
R-426HW
J KEY UNIT TEST
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
6) Reconnect the power supply cord after the outer case is installed.
7) Run the oven and check all functions.
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.
K RELAY 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. Disconnect the leads to the primary of the power transformer.
5. Ensure that these leads remain isolated from other components and oven chassis by using insulation
tape.
6. After that procedure, re-connect the power supply cord.
7. Remove the outer case and check voltage between the normal open terminal of the relay RY1 and the
normal open terminal of the relay RY2 on the control unit with an A.C. voltmeter.
The meter should indicate 120 volts, if not check oven circuit.
RY1 and RY2 Relay Test
These relays are operated by D.C. voltage
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation.
DC. voltage indicated ............... Defective relay.
DC. voltage not indicated ......... Check diode which is connected to the relay coil. If diode is good,
control unit is defective.
Pin
NO. G1
Pin
NO. G13
Key unit ribbon cable
Key unit (Membrane Switch) front view
G13
G12
G11
G10
G9
G8
G7
G5
G4
G3
G2
G1
5
0
69
4
3
8
7
2
1
A
*
A
*
W
H
EN
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IS C
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OSE
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Y
UNIT
POWE
R
L
EVE
L
K
E
E
P
WA
RM
PL
US
FR
ES
H
VEGET
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BL
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FISH
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EAFOOD
FR
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OLL
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U
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R
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(
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EF
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OST
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TEAK
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HOPS
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BONE-IN
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L
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Y
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R
ESH
R
OLLS
M
U
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FIN
S
FR
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N
E
N
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BO
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TR
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REHEA
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ERAG
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P
OT
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(SEN
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OOK)
CU
S
TOM
HEL
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TIM
ER
CL
OCK
HOT
WATE
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G6
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