R-875/885 -
21
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin Nos. 1 and 3 of the 4 pin connector (E) on the
control unit with an A.C. voltmeter.
The meter should indicate 230 volts, if not check oven circuit.
Relay Test
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation, grill
operation, convection operation or dual 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.
RELAY SYMBOL
OPERATIONAL VOLTAGE
CONNECTED COMPONENTS
RY1
Approx. 18.0V D.C.
Oven lamp / Turntable motor
RY2
Approx. 18.0V D.C.
High voltage transformer
RY3
Approx. 24.0V D.C.
Grill (Top) heating element
RY4
Approx. 24.0V D.C.
Bottom heating element
RY5
Approx. 24.0V D.C.
Touch control transformer
RY6
Approx. 24.0V D.C.
Fan motor
RY7
Approx. 24.0V D.C.
Convection motor
CARRY OUT 4R CHECKS.
PROCEDURE
LETTER
COMPONENT TEST
N
KEY AND JOG UNIT TEST
O
RELAY TEST
If the display fails to clear when the STOP button is depressed, first verify the cable is making good
contact, verify that the stop switch operates properly; that is the contacts are closed when the door is
closed and open when the door is open. If the stop switch is good, disconnect the cable that connects
the Jog switch unit to the control unit and make sure the stop switch is closed (either close the door
or short the stop switch connector). Use the Jog switch unit matrix indicated on the control panel
schematic and place a jumper wire between the pins that correspond to the STOP button making
momentary contact. If the control unit responds by clearing with a beep the Jog switch unit is faulty and
must be replaced. If the control unit does not respond, it is a faulty and must be replaced. If a specific
button does not respond, the above method may be used (after clearing the control unit) to determine
if the control unit or Jog switch unit is at fault.
CARRY OUT 4R CHECKS.
J-6
J-3
J-3
J-4
J-7
J-8
J-4
J-7
J-8
J-5
J-2
J-1
J-6
J-5
J-2
J-1
SW11
SW12
SW13
SW8
SW9
SW10
SW5
SW4
SW6
SW7
SW1
SW2
SW3
EXPRESS
STOP
WATT
AUTO
GB
D
NL
F
I
E
FUN
PIZZA
P
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING
BOARD (PWB) IS OPEN
To protect the electronic circuits, this model is provided with a fine foil pattern added to the input circuit
on the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide
given below for repair.
TEST PROCEDURES