Sharp R-8470, R-8570 Service Manual

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R-8470 R-8570

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R-8470 R-8570

OVEN

This Manual has been prepared to provide Sharp Corp. Service

Personnel with complete Operation and Service Information for

the SHARP CONVECTION MICROWAVE ovens, R-8470/

R-8570.

It is recommended that service personnel carefully study

entire text of this manual so they will be qualified to render satisfactory customer service.

Check interlock switches and door seal carefully. Special at-

tention should be given to avoid electrical shock and microwave

radiation hazard.

CAUTION

MICROWAVE RADIATION

Personnel should not be exposed to the microwave energy

which may radiate from the magnetron or other microwave

generating devices if it is improperly used or connected. All input and output microwave connections, waveguides,flanges and gaskets must be secured. Never operate the device without a nicrowave energy absorbing load attached. Never look into

an open waveguide or antenna while the device is energized.

SHARPCORPORATION

OSAKA, JAPAN

PRODUCT

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OPERATION

DESCRIPTION OF OPERATING SEQUENCE

following is a description of component functions

during oven operation.

OFF CONDITION

Closing the

door activates

both door interlock

switches: upper latch switch and lower latch switch.

(In this condition,

the monitor switch contacts are

opened

stop switch is activated (contacts closed) by the

latch head, when the door is closed. When oven is plugged in, the 240 volts A.C. is supplied to the relay unit. (Figure O-l).

display will show flashing To set any program or set the clock, you must first touch the STOP/CLEAR (or STOP/CANCEL) pad.

The display will clear,

and

will appear and

count up every minute.

Note: When the door is opened, the oven lamp comes

on.

2. A signal is input to the control unit, energizing the coil of shut-off relay (RY6).

RY6 contacts close, completing a circuit to the damper motor. The damper motor now operates moving the damper to the open position, thereby closing the contacts of the damper switch inputs a signal to the control unit. The coil of relay RY6 is de-energized, opening its contacts, thereby turning off the damper motor.

COOKING CONDITION

Program desired cooking time and Variable Cooking Control by touching the NUMBER pads and the HIGH pad of the Variable Cooking Control. When the COOK

(or START) pad is touched, the following operations

occur:

1. The contacts of relays are closed and components connected to the relays are turned on as follows.

(For details, refer to Figure O-2)

RELAY CONNECTED COMPONENTS

RY-1 power transformer RY-2

oven lamp/turntable motor

RY-3

convection motor heating element

RY-5

fan motor

RY-6

damper motor

2. The 240 volts A.C. is supplied to the primary wind-

ing of the power transformer and is converted about 3 volts A.C. output on the filament winding, and approximately 2200 volts A.C. on the high voltage winding.

3. The filament winding voltage heats the magnetron filament and the H.V. winding voltage is sent to a voltage doubler circuit.

4. The microwave energy produced by the magnetron

is channeled through the waveguide into the cavity

feed-box, and then into the cavity where the food

is placed to be cooked.

Upon completion of the cooking time, the power

transformer, oven lamp, etc. are turned off, and the

generation of microwave energy is stopped. The oven will revert to the OFF condition.

When the door is opened during a cook cycle,

monitor switch, stop switch, upper latch switch are activated with the following results. The circuits to the turntable motor, the cooling fan motor, and the

high voltage components are deenergized, the oven lamp remains on,

and the digital readout displays

the time still remaining in the cook cycle when the

door was opened.

The monitor switch is electrically monitoring the

operation of the upper latch switch and is mechanically associated with the door so that it will function in the following sequence. (1) When the door opens from a closed position,

the upper latch switch opens their contacts, and then the monitor switch contacts close.

(2) When the door is closed from the open posi-

tion, the monitor switch contacts first open, and then the contacts of the upper latch switch close.

the upper latch switch failes with their contacts

closed when the door is opened, the closing of the

monitor switch contacts will form a short circuit through the monitor fuse, upper latch switch , causing the monitor fuse to blow.

When the Variable Cooking is programed, the 240 A.C. voltage

is supplied

to the power transformer intermittently through the contacts of the relay which is operated by the control unit within a 32 second time base. The microwave power operation is as follows:

VARI-MODE

ON TIME OFF TIME

HIGH

32 sec.

0 sec.

(approx. 100% power)

24 sec.

8 sec.

(approx. 70% power) MEDIUM

18 sec.

14 sec.

(approx. 50% power) MED.LOW( DEFROST) 12 sec.

20 sec.

(approx. 30% power) LOW

6 sec. 26 sec.

(approx. 10% power)

Note: The ON/OFF time ratio does not correspond

with the percentage of microwave power, because approx. 2 seconds are needed for heating of the magnetron filament.

CONVECTION COOKING CONDITION

Program desired convection temperature by touching the CONVECTION pad and the temp. pad. When the START pad is touched, the following operations occur:

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The coil of shut-off relays (RY2, RY3 and RY5) are

energized, the oven

lamp, cooking fan motor,

turntable motor and convection motor are turned

on.

The coil of relay (RY6) is energized by the control

unit. The damper is moved to the closed position, opening the damper switch contacts.

The opening of the damper switch contacts sends

a signal to the LSI on the control unit

de-energizing the relay (RY6) and opening the circuit to the damper motor. The coil of heater relay (RY4) is energized by the

control unit and the mains supply voltage is added

to the heating element.

When the oven temperature reaches the selected

preheat temperature, the following operations oc-

cur:

4-1.

4-2.

The heater relay is de-energized by the control unit temperature circuit and thermistor,

opening the circuit to the heating element.

The oven will continue to function for

minutes, turning the heater on and off, as

needed to maintain the selected preheat temperature. The oven will shut-down completely after

15 minutes.

When the preheat temperature is reached, a beep signal will sound indicating that the holding temperature has

been reached in the oven cavity. Open the door and place the food to be cooked in the oven. Program desired cooking time and convection temper-

ature by touching the NUMBER pad, CONVECTION

pad and Temperature pad.

When the START pad is touched, the following oper-

ations occur: I.

The numbers of the digital readout start the count

down to zero. The oven lamps, turntable motor, cooking fan motor and convection motor are energized.

Heater relay (RY4) is energized (if the cavity tem-

perature is lower than the selected temperature)

and the mains supply voltage is added to the

heating element to return to the selected cooking temperature.

Upon completion of the cooking time, the audible signal will sound, and oven lamps, turntable motor, cooking fan motor and convection motor are de-energized. At the

the convection cycle,

if the cavity air temperature is above 120

the circuit to RY5 will be maintained (by the thermistor circuit) to continue operation of the cooling fan motor until the temperature drops below 100 at which time the relay will be de-energized, turn-

ing off the fan motor. Relay RY3 will however,

open as soon sa the convection cycle has ended,

turning off the convection fan motor. This will now

cool and allow the damper door to open. At the end of the convection cook cycle, shut-off relay (RY6) is energized turning on the damper motor. The damper is returned to the open position,

closing the damper switch contacts which send a signal to the control unit, de-energizing shut-off relay (RY6).

AUTOMATIC MIX COOKING CONDITION

Program desired cooking time and temperature by

touching the number pads and the LOW MIX/BAKE

or HIGH MIX/ROAST pad

When the START pad is touched, the following oper-

ations occur:

The numbers of the digital readout start the count down to zero. The shut-off relay (RY2, RY3 and RY5) are

gized, turning on the oven lamps, turntable motor, and cooling fan motor.

The shut-off relay (RY6) is energized.

The damper door is closed from the open position.

The heater relay (RY4) is energized, adding the

mains supply voltage to the heating element. Now, the oven is in the convection cooking condition. When the oven temperature reaches the selected temperature, the following operations occur: 6-l. The power supply voltages is added to the

heating element and power transformer alternately.

6-2. The heating element operates through the

heater relay (RY4) contacts and the power transformer operates through the cook relay

contacts.

6-3. These are operated by the control unit to

supply alternately within a 32 second time base, convection heat and microwave en-

ergy.

The relationship between the convection and microwave power operations are as follows.

Note: The ON and OFF time ratio does not correspond

with the percentage of microwave power, be-

cause approx. 2 seconds are needed for heating

of the magnetron filament.

Appmx.

184vc

2oo”c

Note: During alternate Microwave/Convection opera-

tion, the convection heater is energized only if the cavity temperature drops below the set temperature.

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SENSOR COOKING CONDITION (R-8570

Using the SENSOR COOK function, the foods are cooked without figuring time, power level or quantity. When the oven senses enough steam from the food, it

relays the information to its microprocessor which will

calculate the remaining cooking time and power level

needed for best results. When the food is cooked, water vapor is developed. The sensor “senses” the vapor and its resistance in-

creases gradually. When the resistance reaches the

value set according to the menu, supplementary cook-

ing is started. The time of supplementary cooking is determined by experiment with each food category and inputted into the LSI.

An example of how sensor works:

1. Broccoli at room temperature. Vapor is emitted very slowly.

2. Heat broccoli. Moisture ‘and humidity is emitted

rapidly. You can smell the aroma as it cooks.

3. Sensor detects moisture and humidity and calcu-

lates cooking time and variable power.

1. Touch SENSOR COOK pad.

NOTE:The oven should not be operated on SEN-

SOR COOK immediately after plugging in the unit. Wait five minutes before cooking on SENSOR COOK.

2. Select desired Sensor setting.

3. Touch START pad.

The coil of shut-off relay (RY-1) is energized, the

oven light and cooling fan motor are turned on, but

the power transformer is not turned on.

4. After about 16 seconds, the cook relay (RY-2) is energized. The power transformer is turned on, microwave energy is produced and first stage is started. The 16 seconds is the cooling time required to re-

move any vapor from the oven cavity and sensor. NOTE: During this first stage, do not open the door

or touch STOP/CLEAR pad.

When the sensor detects the vapor emitted from the food, the display switches over to the remaining cooking time and the timer counts down to zero. At this time, the door may be opened to stir food, turn it or season, etc.

6. When the timer reaches zero, an audible signal sounds.

The shut-offrelay and cook relay are de-energized and the power transformer, oven light, etc. are turned off.

7. Opening the door or touching the STOP/CLEAR pad, the time of day will reappear on the display and the oven will revert to an OFF condition.

COMPUCOOK (R-8570 only)

COMPUCOOK will automatically compute the oven

temperature, microwave power and cooking time for

baking, roasting and broiling. Set the

desired

program by

touching

the

COMPUCOOK pad, and number pad. Enter the weight by touching the Number pads When the START pad is touched, the following operations occur:

1.2.The COOK indicator will light and the Convection Fan Symbol will rot ate.

The cooking time will appear on the display and start counting down to zero. The cooking time is adjusted automatically ac-

cording to the setting quantity or weight of food.

The shut-off relays (RY2, RY3, RY4 and RY5) are

energized, turning on the oven lamp, turntable motor, cooling fan motor and convection motor. The power supplay voltage is added to the heating element.

Now, the oven is in the convection cooking mode. When the oven temperature has reached the programmed convection temperature, the oven goes

into the programmed cooking mode. At the end of the COMPUCOOK cycle, the damper

is returned to the open position and the oven will be off condition. The cooling fan will remain on until the oven has cooled.

COMPU DEFROST COOKING

The COMPU DEFROST key is a special function key to defrost meats and poultry faster and better.

COMPU DEFROST 1 to 5 automatically defrosts roast beef, etc. Each key has 3 defrost stages.

When the desired COMPU DEFROST number is

and the food weight is entered by using

number pad’s, the oven will cook according to

special cooking sequence.

the the

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R-8470 R-8570

oLL

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R-8470

-8570

DESCRIPTION AND FUNCTION OF COMPONENTS

LOWER LATCH

The upper and lower latch switches are activated by the latch heads on the door. When the door is opened, the switches interrupt the circuit to the power transformer, etc. For detais, refer to Oven Schematic diagram. And the switches interrupt the circuit to the heating element for model which is provided the heating element. A cook cycle cannot take place until the door is firmly closed thereby activating both latch switches.

UPPER

LATCH

normally closed. At this time the upper latch switch are in the OFF condition (contacts open) due to their being normally open contacts switches.

2. As the door goes to a closed position, the monitor switch contacts are first opened and then the upper

latch switch contacts close. (When opening the

door, each of these switches operate inversely.).

3. In the door is opened and the upper latch switch contacts fail to open, the fuse blows simultaneously with the closing of the monitor switch contacts.

CAUTION: BEFORE REPLACING A BLOWN FUSE,

TEST THE MONITOR SWITCH, UPPER

LATCH SWITCH FOR PROPER OPERATION. (REFER TO CHAPTER “TEST PROCEDURE”)

The door can be opened by grasping the door handle and pulling strong. When the door is pulled, the lower and upper latch

heads mounted in the door are raised up to release them from the latch hooks. The door can now be opened.

LATCH

SWITCH

MONITOR SWITCH The monitor switch is activated (the contacts opened) by the upper latch head on the door while the door is closed. This switch is intended to render the oven inoperative by means of blowing the fuse when the contacts of the upper latch switch falles to open when the door is opened. Functions:

1. When the door is opened, the monitor switch con-

tacts close (to ON condition) due to their being

LATCH

LOWER LATCH

HEAD

Open

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-8470

R-8570

Usually, the damper is open position except during the

convection cooking.

Damper position is set automatically by damper motor, damper switch, motor cam and damper shaft. These components are operated according to the signal that judges the microwave cooking or convection cooking operation in the control unit.

Microwave Cooking:

Damper is in the open position, because a portion of cooking air is channeled through the cavity to remove steam and vapors given off from the heating foods.

It is then exhausted at the top of the oven cavity into a condensation compartment.

Convection Cooking:

Damper is in the closed position, so that no hot air will

be allowed to leak out the oven cavity.

Damper Operation

1. When power supply cord is plugged in:

l-l.

1-2.

1-3.

I-4.

l-5.

When power supply cord is plugged in, a sig-

nal is sensed in the control unit, and operates

the shut-off relay (RY6).

Contacts of shut-off relay (RY6) close, then

the damper motor is energized, opening the

damper door.

When damper is moved to the open position

by the damper cam damper switch is closed

(ON position). The signal of damper switch is re-sensed in the control unit and shut-off relay (RY6) is turned off. The 240 volts A.C. to the damper motor is stopped and the motor turns off.

2. When oven is microwave cooking: Damper is in the open position.

3. When oven is convection cooking:

3-l. 3-2.

3-3. 3-4.

Damper motor is energized by touching the convection, temperature and START pads. When damper is in the closed position

(damper switch is OFF), its signal is sensed

by the control unit, and shut-off relay (RY6)

is de-energized. The damper is held in the closed position

during the convection cooking operation.

At the end of the convection cooking, the shut-off relay (RY6) is energized, and damper

is returned to the open position.

DAMPER

DAMPER CAM

MOTOR

D-3.

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R-8470 R-8570

SERVICING

When troubleshooting the microwave oven, it is

IMPORTANT: If then oven becomes inoperative

cause of a blown monitor fuse in the

forming the checks. Many of the passible causes of

monitor switch and upper latch switch

trouble will require that a specific test be performed.

circuit, check the monitor switch and

These tests are given a procedure letter which will be

upper latch switch before

found in the “Test Procedure”section.

the monitor fuse.

TEST

Home fuse blows when power

Shorted wire in power cord or wire har-

Replase cord or check wiring.

cord is plugged into wall recepta-

ness.

cle.

Monitor fuse blows when power

Shorted wire in power cord or wire har-

Replace power cord or check

cord is plugged into wall recepta-

ness.

and repair harness.

Defective monitor switch.

Procedure F. Check home fuse.

when power cord is first plugged

Blown monitor fuse.

Psocedure G.

into wall outlet.

Blown magnetron temp. fuse.

Psocedure H.

Open wire in power cord, wiring harness,

Replace or repair wiring. or wiring between control panel assembly units.

Defective control unit.

Procedure K. Defective relay unit.

Procedure J.

Display does not operate properly

Defective key unit.

Procedure L.

when

STOP/CLEAR

key is

touched. (Buzze should sound

defective control unit.

Procedure K.

and time of day should appear in

Defective relay unit

Procedure J.

display.)

Defective stop switch

Procedure E.

Oven lamp does not light with No power in home.

Check wall outlet.

door opened.

Open wire in power cord or wire harness.

poplace same or repair wir-

Defective oven lamp.

Replace.

Defective upper latch switch.

Procedure E.

Open or loose wire connection to the Check wiring. above components.

Blow monitor fuse or magnetron temp.

Procedure G or H.

fuse.

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R-8470 R-8570

COOKING CONDITION

Oven lamp does not light in cook

Defective shut-off relay

on relay Procedure J.

cycle.

unit.

(Does light when door is opened)

Defective control unit

Procedure K

Oven lamp does not light at all.

Burned out bulb.

Replace

Open wiring of oven lamp.

Check and repair wiring

Oven lamp lights, but turntable

Open or loose wiring to turntable motor.

Check and repair wiring

motor does not operate.

Defective turntable motor.

Replace

Turntable motor operates normally

Defective cooling fan motor.

Replace.

but cooling fan motor dies not

Defective shut-off relay (RY5) on relay Replace

operate

unit. Open or loose wiring to fan motor

Check and repair wiring

MICROWAVE

Oven des not go into a cook cycle when START pad is touched.

Oven seems to be operating but little or no heat is produced in

oven load. (Food

incompletely cooked or not cooked at all at end of cook cycle.)

Oven does into a cook cycle but extremely

uneven

heating is

produced in oven load(food). Oven does not cook properly

when programed for MEDIUM etc. cooking powers.

(Operates properly on HIGH)

Oven does not cook properly when programed in COMPU DEFROST cooking mode

Upper and/or lower latch switches

Procedure E.

tive or out of adjustment. Defective cook relay (RYI ) on relay unit.

Procedure J.

Defective control unit.

Procedure K.

Defective key unit.

Procedure L.

Open or loose wiring to above compo-

Check and repair wiring

nents. Defective magnetron.

Procedure A.

Defective cook relay

on relay unit.

Procedure J.

Defective power transformer.

Procedure B.

Defective rectifier.

Procedure C.

Defective high voltage capacitor.

Procedure D.

Defective control unit.

Procedure K.

Open or loose wiring to above compo-

Check and repair wiring nents. Low voltage. Dirty oven cavity.

Turntable motor does not operate. Refer to proceding turntable

motor problem.

Defective control unit.

Procedure K. Defective key unit.

Procedure L. Open or loose wiring to above compo-

Check and repair wiring nents.

Defective COMPU DEFROST function.

Refer to COMPU DEFROST

section on operation manual

and check control unit.

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CONVECTION

CONV indicator light but oven Defective key unit.

Procedure L

does not go into a cook cycle Defective thermistor.

Porcedure N

when START pad is touched.

Open wiring in circuit to above compo- Check and repair wiring. nents.

CONV indicator lights, but heating

Defective heating element.

Procedure I

element does not heat.

Defective heater relay(RY4) on relay unit.

Porcedure J

Defective control unit.

Procedure K

Open or loose wire connection

to the Check and repair wiring.

above components

Temperature in the oven cavity is

Defective heating element.

Procedure I

lower or higher than preset,

Defective control unit.

Porcedure K

Defective convection mortor.

Replace motor.

Defective thermistor.

Procedure N

Defective cooling fan motor.

Replace

Defective dumper motor

Procedure 0

Defective drive mechanism of convection Check.

fan.

SENSOR (R-8570)

Oven is in the sensor cooking AH sensor open and/or short. condition but AH sensor does not

Defective control unit.

Procedure M Procedure K

end stage 1 or does not stop

Open or loose wire connection

to the Check and reapir wiring.

cooking cycle.

above components.

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R-8470 R-8570

TEST

DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING.

To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check across the magnetron filament leads should indicate less than 1 ohm.

To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament

leads and chassis ground.

This test should indicate an infinite resistance. If there is little or no

resistance, the magnetron is grounded and must be replaced.

Power output of the magnetron can be measured by performing a water temperature rise test. This test should only be used if above rests do not indicate a faulty magnetron and there is no defect in the following components or wiring: rectifier, high voltage capacitor, heater transformer and power transformer.

POWER

be measured by using water load how much it can be absorbed by the water load. To measure the microwave output power in the microwave oven, the relation of calorie and watt is used. When P(W) heating works for t(second), approximately P x

calorie is generated. On the

other hand, if the temperature of the water with V(ml) rises AT (

during this microwave

heating period, the calorie of the water is V x AT. The formular is as follows;

P x t

4.2 = V x AT

P (W) = 4.2 x V x AT

Our condition for the water load is as follows:

Water load . . .

2000 ml, Heating time

seconds (2 minutes)

Measuring method;

1. Put the water load of two (2) litres on the

of the oven shelf. The water load should be arranged in two (2) Pyrex beakers, the size of which is one (1) litre, and be placed at right and left, side by side, on the oven shelf.

2. Measure the temperature of water before heating and also after heating during two minutes by microwave, and calculate the temperature rise.

The temperature rise should be the average

of temperature differences measured in each beaker.

3. The output power should be calculated as follows. In case the measuring result is not satisfactory, execute the measurement several times and judge the result from the synthetic point of view. Microwave output power should be within

5% of the nominal one.

Calculation of output power; Microwave output power . ..P (W) = 70 x AT ( “C)

AT = ( ATL + ATR)

2 : average temperature rise

ATL = (TL2

ATR = (TR2

TL2 : water temperature after heating in left beaker

: water temperature before heating in left beaker

TR2 : water temperature after heating in right beaker

Measuring condition; As the microwave output is affected by several conditions, the measurement should be made carefully with following attentions.

1. Initial temperature of salt water should be 20

(The salt water should be contained bon (1) percent of salt.) Well and quickly stir the water and the temperature measurement should be done immediately after heating.

2. The graduation of thermometer should be scaled by 0.1

at minimum and an accurate mer-

cury thermometer is recommended.

Page 16

TEST

3. Water container should be one (1) litre beaker made of Pyrex glass and its diameter approximately

cm.

4. Room temperature should be around 20

5. Power supply voltage should be specification voltage.

TEST

DISCHARGE THE HIGH VOLTAGE

BEFORE TOUCHING ANY OVEN COMPO-

NENTS OR WIRING. Disconnect the primary input terminals and measure the resistance of the transformer with an

ohmmeter. Check for continuity of the coils with an ohmmeter. On the R x 1 scale, the resistance of the primary coil should be less than 1 ohm and the resistance of the high voltage coil should be approximately 73 ohms; the resistance of the filament coil should be less than 1 ohm.

(HIGH VOLTAGES ARE PRESENT TO HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO

MEASURE THE FILAMENT AND HIGH VOLTAGE.)

RECTIFIER TEST

DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING.

Isolate the rectifier from the circuit. Using the highest ohm scale of the meter, read the resistance across the terminals and observe, reverse the leads to the rectifier terminals and observe meter reading. If a short is indicated in both directions, or if an infinite resistance is read in both directions, the rectifier is orobablv defective and should be replaced.

TEST

DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPO-

NENTS OR WIRING.

If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads and check for short or open, between the terminals using an ohmmeter.

Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate continuity for a short time and should indicate an open circuit once the capacitor is charged. If the above is not the case, check the capacitor with the ohmmeter to see if it is short circuited

between the terminals. If it is short circuited, replace the capacitor.

TEST

Isolate the switch and check the connection by using the ohmmeter accord ing to the following table.

If improper operation is indicated, make the necessary switch adjustment or replacement.

Table: Switch Connection

Connection

Common Terminal-Normally Open Terminal

Common Terminal-Normally Close Terminal

Operation

Open circuit

Close circuit

Plunger released Plunger pushed

Closed circuit

Open circuit

TEST

Before performing this test, make sure that the upper latch switch is operating properly referring to the above Switch Test Procedure. Check the monitor switch operation by using the ohmmeter as following figure. When the door is open, the meter should indicate a closed circuit. When the monitor switch lever of the upper latch hook is pushed by a screw driver through the upper latch hole on the front plate of the oven cavity with the door opened (in this condition the plunger of the monitor switch is pushed in), the meter should indicate an open circuit.

If improper operation is indicated, replace the defective switch.

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R-8470

-8570

TEST

LATCH

MONITOR SWITCH LEVER

FUSE

If the monitor fuse in the primary-secondary-monitor switch circuit is blown when the door is opened, check the primary and secondary interlock switches and monitor switch according to the Test Procedure of those switches, before replacing the blown monitor fuse.

If the monitor fuse is blown by improper switch operation, adjust or replace the defective switch and monitor fuse at the same time.

Replace just the monitor fuse if the switches operate normally. CAUTION; REPLACEMENT FUSE MUST BE THE LISTED FUSE IN PARTS LIST.

FUSE TEST

A continuity check across the temp. fuse terminal should indicate a closed circuit. If the temperature of the magnetron reaches 115

temp. fuse opens. If the temp. fuse has opened, replace the fuse. An open temp. fuse indicates overheating of the magnetron assembly. Check for restricted air flow to the magnetron through the opening in the chassis, especially the cooling duct.

TEST

Make sure the heating element is fully cooled and test as follows; a. Disconnect wire leads and measure the resistance with an ohmmeter. On the R x 1 scale, the

resistance between the heating element terminals should be approximately 38.4 ohms.

b. Disconnect wire leads and measure the insulation resistance with 500V

1 OOM

insulation

resistance meter.

The insulation resistance between heating element terminal and cavity should be more than

Page 18

R-8470

-8570

TEST

The relay unit consists of circuits including the shut-off relays, buzzer, transformer, etc.

Plug power cord into wall receptacle “88888” will be flashing in the display. Remove the outer case and check voltage between Pin Nos.

1 and 3 of the

connector

(A) on the relay unit with an A.C. voltmeter. The meter should indicate 240 volts, if not check oven circuit. Shut-off , Cook and Heater Relay Test These relays are operated by D.C. voltage.

Check voltage at the relay coil with a D.C. voltmeter during the microwave or convection 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.

RELAY SYMBOL

(COOK) RY2 RY3 RY4 (HEATER) RY5 RY6

OPERATIONAL

VOLTAGE

Approx. 14 V.D.C. Approx. 14 V.D.C. Approx. 14 V.D.C. Approx. 14 V.D.C. Approx. 14 V.D.C. Approx. 14 V.D.C.

CONNECTED COMPONENTS

Power transformer Oven lamp/Turntable motor Convection motor Heating element Cooling fan motor Damper motor

TEST

The touch control panel consists of circuits including semiconductors such as LSI, Therefore, unlike conventional microwave ovens, proper maintenance cannot be performed with

only a voltmeter and ohmmeter.

In this service manual, the touch control panel assembly is di-

vided into three units Control Unit, Key Unit and Relay Unit and troubleshooting by unit re-

placement is described according to the symptoms indicated.

1. Key Unit.

The following symptoms indicate a defective key unit. Replace the key un it.

a) When touching the pads, a certain pad produces no signal at all. b) When touching a number pad, two figures or more are displayed. c) When touching the pads, sometimes a pad produces no signal.

2. Control Unit

The following symptoms indicate a defective control unit. Replace the control unit.

2-l 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 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 when it lights-up. c) Only one indicator does not light up. 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 troubles 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. d) Proper temperature measurement is not obtained.

Note: When a defective one or more of three components, the Control Unit, Key Unit or Relay

Unit are replaced, the defective part or parts must be properly packed for return in the shipping carton, with its cushion material, in which the new replacement part was shipped to you.

Page 19

R-8470 R-8570

TEST

If the indicator does not respond to touching a key Pad use the following matrix and place a

jumper wire between the proper pin connections with the cable connector disconnected from the

control unit.

If the indicator responds and oven goes into operation, the key unit was faulty. If there is no response, replace the control unit.

KEY UNIT

SENSOR TEST

sensor

(1) The oven should be plugged in at least five minutes

sensor cooking. (2) Room temperature should not exceed 35 (3) The unit should not be installed in any area where heart and steam are generated. The unit

should not be installed, for example, next to a conventional surface unit. Refer to the “INSTALLATION Instruction”.

(4) Exhaust vents are providend on the back of the unit for proper cooling and air flow in the

cavity.To permit adequate ventilation,

be sure to install so as not to block these vents.

There should be some space for air circuration.

(5) Be sure the exterior of the cooking container and the interior of the oven arer dry. Wipe

off any moisture with a dry cloth or paper towel.

(6) The Sensor works with food at normal storage temperature.For example, chicken pieces

would be at refrigerator temperature and canned soup at room temperature. (7) Foods weighing less than 3 ounces should be cooked by time and vaiper power. (8) Avoid using aerosol sprays or cleaning solvents near the oven while using Sensor settings.

The sensor will detect the vapor given of by the spray and turn off

food is propary

cooked. (9) After 30 minutes it the sensor has not detected the vapor of the food, ERROR will appear

and the oven will shut off. When cooking bacon, the sensor must detect the vapor within

1-l

minutes before ERROR appeares and oven shuts off.

load

Make sure the oven has been plugged in at least five minutes before checking sensor cook op-

eration. The cabinet should be installed and screws tightened.

(1) Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup. (2) Place the container on the center of tray in the oven cavity. (3) Close the door. (4) Touch SENSOR COOK pad and number pad 1 .Now, the oven is in the sensor cooking

condition and AS-l will appear in the display.

(5) Touch Start pad.The oven will operate for the first 16 seconds, without generating micro-

wave energy.

When the AH sensor is defective (open or short), ERROR will appear in the display after 16 seconds cooling time.

If ERROR appears check sensor wire connections and/or AH sensor. NOTE: ERROR will appear if the door is opend or STOP/CLEAR pad is touched during first

stage of sensor cooking.

Page 20

R-8470 R-8570

TEST

(6) After approximately 16 seconds, microwave energy is produced,oven should turn off when

water is boiling (bubling).

If the oven dose not turn off, replace the AH sensor or check the control unit, refer to explanation below:

AH SENSOR

To determine if the sensor is defective, the simplest method is to replace it with a new replacement sensor.

(1) Disconnect oven from power supply and remove outer case. (2) Discharge the high voltage capacitor. (3) Remove the AH sensor. (4) Install the new AH sensor. (5) Re-install the outer case. (6) Reconnect the oven to the power supply andcheck the sensor cook operation proceed as

follows: 6-l. Touch SENSOR COOK pad and number 1 pad.

6-2. Touch Start pad. The contorol panel is in the automatic Sensor operation. 6-3. The oven will turn off automatically when the water is boiling (bubling).

If new sensor dose not operate propaly, the problem is with the contorol unit.

TEST

Disconnect the connector-E from the control unit. Measure the resistance of the thermistor with an ohmmeter. Connect the ohmmeter leads to Pin No’s E-l and E-2.

Room Temp.

Resistance

68 “F(20 86 “F(30 Approx. 350 155k

If the meter does not indicate above resistance, replace the thermistor.

TEST

When the power cord is plugged into the wall receptacle, the 240 volts A.C. is supplied to the damper motor and the motor operates until the damper is opened and the damper switch closes. Then the damper motor stops operation.

If the damper motor does not operate, check for input voltage by A.C. volt-meter at the motor.

1. Disconnect the power cord from the wall receptacle.

2. Disconnect the wire loads of motor and connect the meter leads to the wire leads of main wire harness.

3. Reconnect the power cord into the wall receptacle.

If 240 volts A.C. is. indicated at the wire leads, replace the motor. Not indicated, check the wire harness and the relay unit.

TEST

Disconnect the wire leads from the switch terminals and connect the ohmmeter leads to the

common (COM and normaly open (NO) terminal of the switch.

1. When switch actuator is pushed by the damper motor cam, the meter should indicate a closed circuit.

2. When the power cord is plugged into the wall receptacle, the damper motor operates and damper cam rotates. The switch

is released and meter sould indicate an open circuit.

If improper operation is indicated, replace the damper switch.

Page 21

R-8470 R-8570

TEST

THE

type temperature meter must be used.

A low priced bi-metal type thermometer is not reliable or

accurate.

The temperature should be checked approximately 5 minutes after the preheat temperature is

reached (audible signal sounds four times). The temperature experienced may be approximately 20

more or less than indicated on the display, however, in most cases the food cooking results

will be satisfactory.

Difference in power supply voltage will also affect the oven temperature, The household power supply voltage may sometimes become lower than the rated voltage ( 240 ) and cause under-cooking. If the power supply voltage is 10% lower than the rated voltage, longer cooking

time is required by 10% to 20%.

Page 22

R-8470 R-8570

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL

The touch control section consists of the following

units as shown in the block diagram. (1) Control Unit (2) Key Unit (3) Relay Unit

Exchange of signals between each unit is indicated by

the arrows in the block diagram. The principal func-

tions of these units and the signal communicated among them are explained below.

Relay unit consists of six relays (RYI -RY6), power

source circuit and buzzer circuit.

The key unit is composed of a matrix, signals generated

in the LSI are sent to the key unit through

El 1 -El 3and El 5-E17. When a key pad is touched, a signal is completed through the key unit and passed back to the LSI through

to perform the function that was

requested.

Control unit consists of LSI, power source circuit, synchronizing signal circuit, ACL circuit, buzzer circuit, temperature measurement circuit, absolute humidity sensor circuit and indicator circuit.

This LSI controls the temperature measurement signal, AH sensor signal,key strobe signal relay driving signal for oven function and indicator signal.

Source

This circuit generates voltage necessary in the

control unit. Symbol Voltage Application

-5v

(ICI), ACL circuit and tem-

perature measurement circuit

-15v Buzzzer circuit and IC2 IC2 (R-8570 only)

-34v Fluorescent display tube : Grid

and anode voltage

-25V Filament of fluorescent display

tube

VF2

-28V

VF2 voltage

The power source synchronizing signal is available

in order to compose a basic standard time in the

clock circuit.

It accompanies a very small error because it works on commercial frequency.

Cirucit to generate signals resetting the LSI to the initial state when power is supplied.

The buzzer is responsive to signals from the LSI to emit noticing sounds (key touch sound and

completion sound).

Oven

The temperature in the oven cavity is sensed by the thermistor. The variation of resistance according to sensed temperature is detected by the temperature meas-

urement circuit and the result applied to LSI. The result of detecting is given to LSI controlling the relay and display.

Sensor

The circuit detects absolute humidity of a food

which is under cooking, to allow its automatic

cooking.

to “tell” the LSI if the door is open or

To drive the magnetron, heating element, fan motor, convection motor,damper motor, turntable

motor and light the oven lamp.

Indicator element is a Fluorescent Display.

Basicalloy, a Fluorescent Display is triode having a cathode, a grid and an anode. Usually, the cathode

of a Fluorescent Display is directly heated and the filament serves as cathode. The Fluorescent Display 7-digits, 15-segments are

used for displaying figures.

Page 23

-8470

-8570

Page 24

R-8470

-8.570

1X2429)

The I/O

I of the LSl(lX2429) is detailed in the following table.

DESCRIPTION OF LSI

PIN NO.

SIGNAL

EO-E5

OUT

Refer to the touch control panel circuit about the relation between signals and digits. Normally, one pulse is output in every synchronized signal period, and input to the grid of the fluorescent display.

PIN NO.

SIGNAL

OUT

signals.

Refer to the touch control panel circuit about the relation between signls and indicators. Normally, one pulse is output in every synchronized signal period, and input to the grid of the fluorescent display.

PIN NO.

Signal similar to E6.

SIGNAL

OUT

Signal applied to touch-key section. A pulse signal is input to

terminal while one of G-2 line keys on key matrix is touched.

PIN NO.

Signal similar to E6.

SIGNAL

OUT

Signal applied to touch-key section. A pulse signal is input to

terminal while one of G-3 line keys on key matrix is touched.

PIN NO.

Signal similar to E6.

SIGNAL

OUT

PIN NO.

SIGNAL

El1

OUT

Signal similar to E6.

Signal applied to touch-key section. A pulse signal is input to

terminal while one of G-4 line keys on key matrix is touched.

PIN NO.

Signal similar to

SIGNAL

El2

OUT

Signal applied to touch-key section. A pulse signal is input to

terminal while one of G-5 line keys on key matrix is touched.

PIN NO.

SIGNAL

El3

OUT

Signal similar to E6. Signal applied to touch-key section.

A pulse signal is input to

terminal while one of G-6 line keys on key matrix is touched,

Page 25

R-8470 R-8570

PIN NO.

SIGNAL

El4

data siqnal.

Signal similar to E6.

PIN NO.

SIGNAL

El5

OUT

data siqnal.

Signal similar to E6.

siqnal.

Signal applied to touch-key section. A pulse signal is input to

terminal while one of G-7 line keys on key matrix is touched.

data siqnal.

Signal similar to E6.

siqnal.

SIGNAL

El6

OUT

Signal applied to touch-key section. A pulse signal is input to

terminal while one of G-8 line keys on key matrix is touched.

PIN NO.

SIGNAL

El7

OUT

siqnal.

Signal similar to E6.

siqnal.

Signal applied to touch-key section. A pulse signal is input to

terminal while one of G-9 line keys on key matrix is touched.

PIN NO.

SIGNAL

OUT

siqnal.

Signal similar to E6.

PIN NO.

21-24

SIGNAL

E23

OUT

R-8470: Terminal not used. Connected to GND.

R-8570:

Used for initial balancing of the bridge circuit(absolute himidity sensor).

PIN NO.

SIGNAL

clock

The internal clock frequency is set by inserting the ceramic filter oscillation circuit with respect to X terminal.

PIN NO.

SIGNAL

OUT

clock

Output to control oscillation

of EX.

PIN NO.

SIGNAL

RESET

Signal is input to reset the LSI to the initial state when power is supplied. Temporarily set to “L” level the moment power is supplied, at this time the LSI is reset. Thereafter set at “H” level.

PIN NO.

data siqnal.

Signal similar to E6.

SIGNAL

SO E24

OUT

Page 26

PIN NO. 29

SIGNAL E25

OUT

R-8470: Terminal not used. R-8570: Used for initial balancing of the bridge circuit(absolute himidity sensor).

NO.

SIGNAL

E26

I/O

OUT

sound buzzer.

A: Key touch sound.(0.12 sec.) B: Completion sound. (2.4 sec.) C: When the temperature of the oven cavity reaches the preset temperature in the preheating mode, or when the

preheating hold time (15 minutes) is elapsed. (1.2 sec. ON-l

sec. OFF repeat)

PIN NO. 31

SIGNAL

IRQ E27

This is the basic timing for time processing of LSI.

PIN NO.

SIGNAL

Vss

source

VC voltage of power source circuit input.

PIN NO.

SIGNAL

To turn on and off the cook relay.

OUT

In HIGH operation, the signals holds “L” level during microwave cooking and “H” level while not cooking. In other cooking modes (MED. HIGH, MED., MED. LOW, LOW) the signal turns to “H” level and “L” level in repetition according to the power level.

PIN NO.

SIGNAL

OUT

To turn on and off the control relay. The pulse signai(50Hz) is delivered to the control relay driving circuit and cook relay and heater relay control circuit.

PIN NO.

SIGNAL

OUT

To turn on and off the heater relay. “L” level during convection cooking; “H” level otherwise. During convection cooking or mix cooking, the signal becomes “H” level when the temperature of the oven, cavity exceeds the predetermined temperature.

PIN NO.

SIGNAL

OUT

To turn on and off the cooling fan motor relay.

“L” level during both microwave and convection cooking; “H” level

otherwise.

PIN NO.

SIGNAL

OUT

To turn on and off the convection motor.

“L” level during CONVECTION or MIX COOK; “H” level otherwise.

Page 27

R-8470 R-8570

PIN NO.

SIGNAL

signal.

To turn on and off the damper motor relay.

OUT

PIN NO.

signal.

Signal similar to EO.

SIGNAL

OUT

PIN NO.

SIGNAL

signal

Damper opened; “H” level signal. Damper closed; “L” level signal.

PIN NO.

SIGNAL

E37

change

Signal in accordace with the model in operation is applied to set up its function.

PIN NO.

SIGNAL

E36

signal

LSI.

Door closed; “H” level signal. Door opened;

“L” level signal.

PIN NO.

Connected to VC.

SIGNAL

PIN NO.

SIGNAL

AVR-

A reference voltage applied to the A/D converter in the LSI. The reference voltage is generally maintained at -5V.

PIN NO.

SIGNAL

AVR+

A reference voltage applied to the A/D converter in the LSI.

PIN NO.

Connected to GND.

SIGNAL

PIN NO.

SIGNAL

AN7

key.

When either one of G-l 3 line keys on key matrix is touched, a corresponding signal out of

-El 3 and

will be input into AN7.

When no key is touched, the signal is held at “L” level.

PIN NO.

SIGNAL

AN6

key.

When either one of G-12 line keys on key matrix is touched, a corresponding signal will be input into AN6.

PIN NO.

SIGNAL

AN5

kev.

When either one of G-l 1 line keys on key matrix is touched, a corresponding signal will be input into AN5.

PIN NO.

SIGNAL

AN4

key.

When either one of G-10 line keys on key matrix is touched, a corresponding signal will be input into AN4.

Page 28

-8470

R-8570

PIN NO.

SIGNAL

AN3

I/O

R-8470:

Terminal not used. No connection.

R-8570: Used for initial balancing of the bridge circuit (absolute humidity sensor).

This input is an analog input terminal from the AH sensor

connected to the A/D converter built into the

PIN NO.

R-8470:

SIGNAL

AN2

Terminal not used. No connection.

R-8570:

sensor

This input is an analog input terminal from the AH sensor circuit,

and connected to the A/D converter built into the

PIN NO.

SIGNAL

AN1

By inputting DC voltage corresponding to the temperature detected by the thermistor, this input is converted into

temperature by the A/D converter built into the LSI.

PIN NO.

SIGNAL

AN0

Terminal not used. Connected to GND.

PIN NO. 55

SIGNAL

Terminal not used. Connected to VC.

OUT

PIN NO.

56-60

Terminal not used.

SIGNAL

PIN NO.

SIGNAL

Terminal not used. Connected to GND.

PIN NO.

SIGNAL

Normally connected to VC.

PIN NO.

SIGNAL

Terminal not used. Connected to GND.

PIN NO.

Connected to GN D.

SIGNAL

Vcc

Page 29

-8470

R-8570

ABSOLUTE HUMIDITY SENSOR CIRCUIT (R-8570

Sensor

The absolute humidity sensor includes two thermistors as shown in the illustration. One thermister is housed in the closed vessel filled with dry air while another in the open vessel. Each sensor is provided with the protective cover mode of metal mesh to be protected from the external airflow.

Internal Structure of

The figer below shows the basic structure of an absolute humidity sensor.

A bridge circuit is

by two thermistors and two resistors (RI and R2). The output of the bridge circuit is to be amplified by the operational amplifier.

Each thermister is supplied with a current to keep itself heated at about 150

(302 “F) and the resultant heat is dissipated in the air and if the two thermistors are placed in different humidity conditions they

show different degrees

of heat

leading to potential difference between them causing an output voltage from the bridge circuit, the intensity of which is increased as the absolute humidity of the air increases. Since the output is very minute, it will be amplified by the

operational amplifier.

This detector circuit is used to detect the output voltage of the a absolute humidity circuit to allow the LSI to control the sensor cooking of the unit. When the unit is set in the sensor cooking mode, 16 seconds later the detector circuit starts to function and the LSI observes the initial voltage availabel at its AN2 terminal. With this voltage given, the switches SW1 to SW5 in the LSI are

turned on in such a way as to change the resistance values in parallel with R50.

Changing the resistance values results in that there is the same potential at both F-3 terminal of the absolute humidity sensor and AN3 terminal of the

The voltage of AN2 terminal will indicate

about -2.5V. This initial balancing is set up about

16 seconds after the unit is put in the Sensor Cooking mode. As the sensor cooking proceeds, the food is heated to generate moisture by which the resistance balance of the bridge circuit is deviated to increase the voltage available at AN2 terminal of the LSI. Then the LSI observes that voltage at AN2 terminal and

compares it with its initial value, and when the comparison rate reaches the prest value (fixed for each menu to be cooked), the LSI causes the unit to stop the sensor cooking; thereafter, the unit gets in the next necessary operation automatically.

When the LSI starts to detect the initial voltage at

AN2 terminal 16 seconds after the unit has been put in the Sensor Cooking mode, if it is impossible to take a balance of the bridge circuit due to disconnection of the absolute humidity sensor, ER-

ROR will reappear on the display and the cooking is stopped.

1 )Absolute humidity sensor circuit

I”

. .

2)lnternal equivalent circuit of

Top View

Page 30

A -8470

-8570

SERVICING

Precautions for Handing Electronic

Components

This unit uses PMOS LSI in the integral part of the

circuits. When handing these parts, the following precautions should be strictly followed.

PMOS LSI have extremely high impedance at its input and output terminals. For this reason, it is easily influenced by the surrounding high voltage power source, static electricity charged in clothes, etc,and sometimes it is not fully protected by the

built-in protection circuit.

In order to protect PMOS LSI.

1) When storing and transporting, throughly wrap them in aluminum foil. Also wrap PW boards containing them in aluminium foil.

2) When soldering,

ground the technician as shown in the figure and use grounded soldering iron and work table.

Touch

Panel

We describe the procedures to permit servicing the touch control panel of the microwave oven and the cautions you must consider when doing so. To carry the servicing, power supply to the touch control panel is available either from the power line of the oven proper itself of from an external power source.

panel

supply

oven proper:

OVEN IS STILL

YOU

SER-

Therefore, when checking the performance of the touch control panel,put the outer cabinet on the oven proper to keep you from touching the high voltage transformer, or unplug the primary terminal (connector) of the high voltage transformer to turn it off; and the end of such connector shall be insulated with an insulating tape. After servicing, be sure to replace

the leads to their original locations.

A. On some models, the power supply cord be-

tween the touch control panel and the oven

proper is so short that they can’t be separated

from each other.

For those models, therefore, check and repair all the controls (with the sensor-related ones included) of the touch control panel while keeping it in contact with the oven proper.

On some models, on the other hand, the power supply cord between the touch control panel and the oven proper is so long that they may

be separated from each other. For those models, therefore, it is allowed to check and repair the controls of the touch control panel while

keeping it apart from the oven proper;in this

case you must short both ends of the stop switch (on PWB) of the touch control panel

with a jumper, which brings about an opera-

tional state that is equivalent to that with the

oven door being closed.

As to the sensor-related controls of the touch

control panel, their checking is allowed if the

dummy resistor(s) whose resistance is equal to

that of those controls is used.

panel

Disconnect the touch control panel completely from the oven proper,and short both ends of the stop switch (on PWB) of the touch control

state that is equivalent that with the oven door

being closed. And connect an external power source to the power input terminal of the touch

control panel, and then it is allowed to check

and repair the controls of the touch control

in the case of (1 )-B above, it is here

also possible to check the sensor-related controls of the touch control panel by using the

dummy resistor(s).

Tools

Tools required when serivicing the touch control panel assembly.

1) Soldering:

3ow

(To prevent leaking current, it is recommended to

use a soldering iron with grounding terminal.)

2) Oscilloscope: Single beam, frequency range: DC

type or more ad-

vanced model.

3) Others:

Other tools

1) When turning on the power source of the con-

trol unit, remove the aluminum foil applied for

preventing static electricity.

2) Connect the connectors of the indicator and

key units to the control unit taking care that the lead wires are not twisted.

After aluminum foil is removed, take extra care

that abnormal voltage due to static electricity

etc. is not applied to the input or output terminals.

4) Attach connectors, electrolytic capacitors, etc.

to PWB, taking care that all connections are tight.

5) Be sure to use specified components where

high precision is required.

Page 31

Page 32

R-8470 R-8570

MAGNETRON ASSEMBLY REMOVAL

Disconnect oven from power supply and remove

6. Lower the magnetron assembly until the tube is

outer case.

clear of the waveguide.

2. Discharge the high voltage capacitor.

7. Remove single (1) screw holding the cooling duct

3. Disconnect wire leads from the magnetron

(B) to the magnetron assembly.

bly.

8. Remove the cooling duct (B) from the magnetron.

4. Release the tab which is provided on cooling duct

CAUTION:

WHEN REPLACING THE MAGNETRON,

(B) to hold cooling duct (A).

BE SURE THE R.F. GASKET IS IN

5. Carefully remove four (4) mounting screws holding

PLACE

AND

THE

MAGNETRON

the magnetron assembly to waveguide while sup-

MOUNTING SCREWS ARE TIGHTENED

porting the magnetron assembly from below.

SECURELY.

CONVECTION MOTOR REMOVAL

1. Disconnect oven from power supply and remove outer case.

2. Disharge the high voltage capacitor.

3. Disconnect wire leads from the convection motor.

4. Remove two (2) screw holding the convection motor assembly to the chassis support and waveguide flange.

The convection motor assembly is now free.

7. Remove the two (2) screw and nuts holding the mounting bracket to the motor

8. Remove the pin and pulley (B) from the motor shaft.

5. Remove the convection fan belt.

6. Lift up the convection motor assembly and remove it from the unit.

9. The convection motor is now free. Note: The motor mounting plate with the convection

motor should be installed in close contact with the waveguide flange. Otherwise, the revolution of the convection fan belt may be disrupted.

COOLING FAN

MOTOR REMOVAL

1. Disconnect oven from power supply and remove outer case.

7. Remove the duct (A) with the cooling fan motor attached from the unit.

2. Discharge the high voltage capacitor.

3. Disconnect wire leads from the cooling fan motor.

4. Remove screw holding the grounding wire to the oven cavity flange.

5. Remove four (4) screw holding the chassis support to rear cabinet, cooling duct (A), convection motor mounting plate and control panel back plate.

6. Release the tab which is provided on

(B) to hold the cooling duct (A).

cooling duct

The cooling fan motor assembly is now free.

8. Remove the fan blade from the cooling fan motor shaft by pulling the fan retainer clip.

9. Remove two (2) screws and nuts holding the cooling fan motor and grounding wire to the cool-

ing duct (A).

The cooling fan motor is now free.

1. Disconnect oven from power supply outer case.

and remove

2. Discharge the high voltage capacitor.

3. Remove the magnetron assembly, refer to “Magnetron Assembly Removal”.

4. Disconnect two (2) connectors for the damper motor from the relay unit.

5. Disconnect two (2) connectors for the stop switch from the relay unit.

DAPMER ASSEMBLY

6. Remove two (2) screw holding the damper duct to oven cavity right-side.

7. Remove single (1) screw holding the damper duct

to rear cabinet.

8. Remove two (2) screws holding the damper duct to top of the oven cavity.

9. Remove the damper assembly from the unit.

Page 33

Page 34

UPPER/LOWER LATCH SWITCHES AND MONITOR SWITCH ADJUSTMENT

If the upper and lower latch switches and monitor switch do not operate properly due to a mis-adjustment, the following adjustment should be made.

1. Loosen the one (1) screw holding the upper latch hook to the oven cavity front flange and the one (1) screw holding the lower latch hook to the same

flange.

2. With the door closed, adjust the lower latch hook by moving it back and forward and then adjust the upper latch hook by moving it back and forward, or up and down. In and out play of the door allowed by the upper and lower latch hooks should be less than 0.5 mm. The vertical position of the upper latch hook should be placed where the upper latch switch and monitor switch have activated with the door closed. Vertical adjustment of the lower

latch hook is not possible.

3. Secure the screws with washers firmly.

4. Now, make sure of the upper latch switch operation. If the upper latch switch has not activated with the door closed, loose the one (1) screw holding

the upper latch hook to the oven cavity front flange

and adjust the upper latch hook position.

After the adjustment, make sure of the following

points:

1. The in and out play of the door remains less than

0.5 mm at latched position. First check the upper latch hook position, pushing and pulling the upper portion of door toward the oven face. Then check the lower latch hook position, pushing and pulling the lower portion of door toward the oven face.

Both results (plays of the door) should be less than

2. The upper and lower latch switches interrupt the circuit before the door can be opened.

3. The monitor switch contacts close when the door

is opened.

4. Re-install the outer case and check for microwave

leakage around the door with an approved microwave survey meter. (Refer to Microwave Measurement Procedure.)

Latch

Page 35

Page 36

R-8470 R-8570

MICROWAVE MEASUREMENT

After the adjustment of the door latch switches, monitor switch and door are completed individually or collectively, the following leakage test must be performed with a survey instrument and it must be confirmed that the result meets the requirements of the performance standard for microwave oven.

The safety switch must prevent microwave radiation emission in excess of 5mW/cm2 at any point 5cm or more from external surface of the oven.

THE

Before beginning the actual test for leakage, proceed

as follows;

Make

test instrument is operating normally as specified in its instruction booklet. Important: Survey instruments that comply with the requirement for instrumentations prescribed by the performance standard for microwave ovens must be used for testing.

Recommended instruments are: NARDA 8100 NARDA 8200 HOLDADYA HI 1500 SIMPSON 3800M

2. Place the turntabel tray into the oven cavity.

3. Place the load of 275

of water initially at

in the centre of the oven tray. The water container should be a low form of 600 ml beaker with inside diameter of approx.

and made of an electrically non-conductive material such as glass or plastic.

The placing of this standard load in the oven is im-

portant not only to protect the oven, but also to in-

sure that ny leakage is measured accurately.

4. Close the door and turn the oven ON with the timer set for several minutes. If the water begins to boil

before the survey is completed, replace it with 275ml of the cool water.

5. Move the probe slowly (not faster that 2.5cm/sec.) along the gap.

6. The microwave radiation emission should be meas-

ured at any point of 5cm or more from the external

surface of the oven.

Page 37

R-8470 R-8570

TRAY PACKING FOAM

Not

Items

Page 38

a 0

N-A

PANEL

____

Page 39

R-8470

R -8470

R-8570

IN)

r-l

Q30 DTA143 A

C81

TURNTABLE

MOTOR

OVEN LAMP

FAN MOTOR A-9

A-7

A-5

DAMPER MOTOR

DTA143 A x5

IF NOT SPECIFIED,1/4W 5%

NOT SPECIFIED,

IF NOT SPECIFIED, US1060

R76 lk

R71

R66 lk

R65 130 F

C65

DAMPER

STOP SWITCH

SWITCH

(DOOR SWITCH)

Figure S-2. Contorol Panel Circuit (Mot

3 4

5 6

Page 40

R-8470 R-8470 R-8570 R-8570

R66

130 F

KEY UNIT

R97

CC.

OVEN

I Panel Circuit (Model R-8470)

Page 41

R-8470

R-8570

AC240

TURNTABLE

MOTOR

OVEN LAMP

POWER TRANSFORMER

HEATING

ELEMENT

FAN

DAMPER

DTA143 A x!

IF NOT SPECIFIED,1/4W 5%

IF NOT SPECIFIED,

25V

IF NOT SPECIFIED, US1060

R76 lk

R75

R52

STOP OVEN

THERMISTOR

Page 42

R-8470

-8570

NAL

HIGH MEDHIGH

STOP INSTANT TIMER

START

HOLD DEFROST

(KEY UNIT

SENSOR

Circuit

R-8570)

Page 43

R-8470 R -8570

Unit)

3 4

5 6

Page 44

PARTS LIST

Mains supply cord

I- 2

YBEO

Fuse (Ml OA)

I- 3

Fuse holder

QSW- MO1 71 WREO

Upper latch switch (V-l

C25)

I- 5

QSW-

73WRE0

Lower latch switch (V-l

QSW- MO1 72WRE0

Monitor switch (V-l

I- 7

Oven lamp

QFS-

Temp. fuse

RMOTDA021 WREO

Turntable motor

l-10

7WRE0 Fan motor

l-11

Convection motor

1-12 .

8WRE0

Damper motor

1-13

QSW- MO1 74WRE0

Stop switch and damper switch (V-5330DK)

1-14

RHET- A01 1 WREO Heating element

1-15

FH-

Thermistor

l-16

RTRN-

Power transformer

1-17

RC-

33WRE0

High voltage capacitor

1-18

RH-

Rectifier

1-19

RH-

Short protector

l-20

RV-

Magnetron

RTRN-A013DREO

Transformer (for control unit)

l-22

AH sensor: R-8570 only

CABINET PARTS

1 2 3 4 5

6 7 8

9 2-10 2-l 1 2-12 2-l 3 2-l 4 2-l 5 2-16 2-l 7

Base cabinet (A)

Base cabinet (B) Rear cabinet Foot

53WRR0

Schematic diagram: R-8470

TMAPCAl 54WRR0

Schematic diagram: R-8570 Capacitor holder Cushion Cord holder Outer case cabinet Shading cushion (A) Capacitor mounting bracket

Vibration proof cushion

PCAS-

Plug case Cord mounting bracket Cord bushing Cord anchorage (lower) Cord anchorage (upper)

CONTROL PANEL PARTS

1E 1F

c75

C31,

c53,

c75

Cl0

CPWBF21 3SWRK0

Control unit: R-8470

CPWBF21 4SWRK0

Control unit: R-8570

connector (D)

connector (E)

3-pin connector (F),(H): R-8570

connector (G)

QCNCMA047 DREO

2-pin connector (H): R-8470

RV-

Fluorescent display tube

RC-

Capacitor 10

RC-

DREO Capacitor

4.7

RC-

Capacitor

0.015

25V 5ov 25V: R-8470

RC-

Capacitor 0.015

25V: R-8570

RCRCRC-

Capacitor Capacitor Capacitor

100

16V 25V 16V

ELECTRICAL

1 1 1 1 1 1 2 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1

1 1 4 1 1 1 1

1 1 1 1 1 1

1 1 1

2 1 7

1 1 1

AF AG AG AG AH AG

AW AW

AR AH

Page 45

R-8470 R-8570

Note

: The voltage supplied to the parts marked

is greater than

Refer to “REPLACEMENT PARTS LIST” described at after page.

NO.

CODE

D83,

D105

D52,

D83,

Ql 00

R2 R3 R4 R22, R82,

R201

R82, R203

R202 R30 R50 R51

R92,

R65

R71,

R76,

R201 R67 R70, R75,

R81,

R83 R84

R113 R200 R204

ZD2 ZD30

RC-

04QDRE0 RCRC-

RCRSRH-

RH-

Diode (US1 060): R-8570

17 AA

RH- DZAOl 1 DREO RH- DZAOl 1 DREO

RH- i RH- i ZOO21 WREO RH-

RH- TZA042 DREO

Diode (11 ES1 ): R-8470

R-8570

IC (lR94558): R-8570 only

Transistor

3 AB 1

RH-

Transistor (

R-8570

6 AB

RH-TZA025DREO

RH-

Transistor Transistor

R-8470

1 5

1 1 1 1 1 4

1 1 1

1 4

1 3

1 1 1 1 1 1 1 1

1 1 1

AB AB

RH- TZA021 DREO

RR- DZ331 NDREO

RR-

51 PDREO

RR-

21 PDREO

RR- DZ271 PDREO

RR-

AC AA AA AA AA AA

RR-

Transistor

OMR) Resistor 330 Resistor

150 Resistor Resistor 270 Resistor 47k

Resistor 47k

Resistor

Resistor 470 Resistor block Resistor

330

Resistor

R-8470

R-8570 AA

RR-

53DDRECI

RR- DZ471 NDREO RRRR- DZ331 PDREO

RR-

03DDRE0

R-8570

AA AA AA AA

RR-

31 NDREO

RR-

02DDRE0

RR-

02DDRE0

RRRR-

RR-

03DDRE0

RRRR- DZ222 DREO RRRRRRRRRRRR-

NDREO RHRH- EZA051 DREO RH-

Capacitor

0.1

Capacitor

0.47

Capacitor

3.3

Ceramic filter

Diode (US1 060): R-8470

25V: R-8570 25V

5ov

Resistor

130

Resistor

Resistor 27k

Resistor

Resistor Resistor block (1 Resistor block (27k Resistor block (56k Resistor 56k Resistor

200k

Resistor

200 Zener diode Zener diode (RD5.1 EB3) Zener diode

R-8470

R-8570

R-8470

1 l4W: R-8570 only

14 AA

AA AA

AA AB AC AD AA AA AA

Page 46

-8470

-8570

Note : The voltage supplied to the parts marked ‘I*” is greater than

Refer to “REPLACEMENT PARTS LIST” described at after page.

Q’TY

CODE

3-2

2A 2c

2E Cl c2

Cl 80 D84, Fl

R21 R40 R41

RY6

5 6 7

4-l 0 4-l 1 4-l 2 4-l 3 4-14 4-l 5 4-l 6 4-l 7 4-l 8 4-l 9

4-20 4-21 4-22 4-23 4-24 4-25 4-26

4-27

4-28 4-29 4-30 4-31 4-32 4-33 4-34 4-35 4-36 4-37 4-38 4-39 4-40

4-41

QCNCM231

VW1

042

06n

QFS-

VRD-

83J VRDVRD-

54J VRD-

J RRLY- 21 RALM- 2021YAZZ RH-

WREO

A031 WRRO

59WRJ0

FOVNNCPL-

NTNT-

X-

5YBE0

PDUCPDUC-

40WRW0

24WRE0

LANGK031 1 WRFO PDUC-

PDUC-

PDUCFDUC- 01 91 WRWO

PREFH0031 WRPO

PFPF-

PFPFPFPFPDUCPDUCFSKR- AOO2WRWO

Relay unit

connector (A)

wire connector

8-pin connector (I)

Fuse holder Capacitor

0.1

Capacitor

1000

Capacitor

0.1

Capacitor

10 Diode (11 El ) Diode (US1 060)

5ov 35v 25V 5ov

Fuse Filter coil (22

Transistor

Resistor Resistor Resistor 150k Resistor

470 Relay Buzzer

Varistor

Key unit: R-8470 Key unit: R-8570 Display filter Control panel frame Key unit angle Control panel back plate

OVEN PARTS

Oven cavity Shading cushion (B)

Turntable coupling Turntable tray

Oven lamp glass flange

Waveguide cover

Oven lamp screen glass Oven lamp mounting plate Magnetron cooling duct (A) Magnetron cooling duct (B)

Turntable motor mounting plate

Fan blade assembly Hinge mounting plate Chassis support Upper latch hook Monitor switch lever Lower latch hook

Stop switch lever Steam duct (left): R-8470 Steam duct (left): R-8570 Steam duct (right)

. Steam duct (upper) Steam duct (top) Steam duct cushion (A) Air guide duct Thermal protection plate (left) Thermal protection plate (right) Thermal protection plate (oven cavity top) Thermal protection plate (upper) Thermal protection cover Sensor cover: R-8570 only Steam duct cushion (B) Thermal protection sheet (right) Thermal protection sheet (left)

Thermal protection sheet (upper)

Convection air duct (upper) Convection air duct (left) Convection air guide (left) Convection air guide (upper) Convection fan Convection fan belt Pulley A (for convection fan)

1 1

1 1 1

1 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

AF AG AH

AF AC

AE AD AG AH AA

AE AH

AF AN AG

AE AA

AK AK

AF AC

Page 47

R-8470 R-8570

The voltage supplied to the parts marked

is greater than

: Refer to “REPLACEMENT PARTS LIST” described at after page.

NO.

Q’TY

CODE

4-42

NPLYB0031 WRFO

Pulley 0 (for convection motor)

4-43

Convection motor mounting plate

4-44

WREO

Fan shaft

4-45

X-

Shaft mounting plate (A)

4-46

Shaft mounting plate

4-47

Heating element holder

4-48

PDUC- A071 WRWO

Damper duct

4-49

PFTA-

Damper

4-50

NSFTT0071 WREO

Damper shaft

4-51

Damper cushion

4-52

1 WREO

Damper cam

4-53

PCUSU0471 WRPO

Steam duct cushion (C)

4-54

SH0041 WREO

Heating element insulator

4-55

Turntable roller assembly

1 2 3 4 5 6 7 8

9 5-10 5-l 1 5-l 2 5-13 5-14 5-15 5-16 5-17 5-18

5-l 9 5-20 5-21 5-22 5-23

Door assembly, complete: R-8470

Door assembly, complete: R-8570

Latch plate

Joint lever

LSTPPAOl

Upper latch head

LSTPPAOl

Lower latch head

Latch spring

Door sash upper

Door panel ass’y

Door sash (right)

Latch cover

LX-

Screw (torx); latch cover mtg

HDECQA041 WREO

Door sash (lower)

Door decoration plate

Ferrite

Sash mounting plate (upper)

Sash mounting plate (lower)

FHNG-

Door hinge ass’y

Door sash (left)

Door glass: R-8470

Door glass: R-8570

PCUSG021 3WRP0

Door sushion (short)

PCUSG021 2WRP0 Door cushion (long)

Door ferrite (upper)

LX-

7WRE0

Screw; sash mounting plate mtg

LX-

Screw; door hinge ass’y mtg

6-l 0 6-l 1

6-12 6-13

QW-

FW-

86WRE0

FW-

85WRE0

TSPCNA31 2WRR0

3WRR0

69WRR0

70WRR0

SCREWS, NUTS, WASHERS,

1 LX 2

LX-

41 WREO

3 LX-

86WRE0

4 LX-

7WRE0

5 LX-

6 LX-

MISCELLANEOUS

High voltage wire A (Trans.-Capa.) High voltage wire B Main wire harness Thermistor harness Wire holder Wire holder

lock “EXL”) Wire holder (WH-1 Name plate: R-8470 Name plate: R-8570 Caution label Cook book Operation manual: R-8470 Ooeration manual: R-8570

Screw

waveguide cover mtg

Screw

monitor switch lever mtg

Screw ; cord mounting bracket, capacitor mounting bracket,

magnetron cooling duct (B), base cabinet (A) and rectifier

Screw ; convection air guide (upper) mtg Screw ; rear cabinet, base cabinet (A), (B) and control panel

assembly mtg

Screw

upper and lower latch hook mtg

1 1 1 1 1 1

2 1 1 1 1 1 1

AC AC AL AL

AA AA AC AA

AE AD AC AC AC

AK AA

AS AH

AZ AA

AE AA AA

AS AD AD

AL AA AA AA AC

AK AN

AA AA AA

AA AA

Page 48

R-8470 R-8570

Note :

is greater than

: Refer to “REPLACEMENT PARTS LIST” described at after page.

Q’TY

CODE

7 8

9 7-10 7-11 7-12 7-13 7-14 7-15 7-16 7-17

7-18 7-19 7-20 7-21 7-22

7-23 7-24 7-25 7-26 7-27 7-28

7-29 7-30

7-32 7-33 7-34 7-35

7-36

7-37 7-38 7-39 7-40 7-41

LX-

Screw ; outer case cabinet mtg

2 AB

Screw ; fuse holder mtg

Screw ; damper switch mtg

Screw ;

fan motor and convection motor mtg

4 AA

Screw ;

magnetron mtg

2KS0 Screw ; magnetron mtg

4KS0 Screw ; power transformer mtg

Screw ;

heating element mtg

2 AA

2000

Screw ; door assembly mtg

4 AA

Screw ;

waveguide cover mtg 3

Screw

damper duct, convection air duct (upper), (left), oven 17

lamp mounting plate and shaft mounting plate mtg

Screw ; thermistor mtg 2

AA Screw ; AH sensor and sensor cover mtg: R-8570 6 AA Screw ;

oven lamp mtg

0000 Screw ; damper motor mtg 2

AA Screw ;

damper duct, steam duct (right), (left), (upper), thermal

protection plate (right), (left), thermal protection cover, oven lamp mounting plate, sensor cover and air guide duct

X C P S D4 0 P 2 7 0 0 0

Screw ; cord anchorage (upper) mtg 2 AA

oxuo

Screw ;

heating element holder and heating element insulator mtg 4 AA

Screw ; convection motor mounting plate and damper duct mtg

0000

Screw ;

cord anchorage (lower) mtg

0000

Screw ;

plug case mtg

2XS0

Screw ; transformer (for control unit), relay unit and control unit 8 AA

2000

Screw ;

outer case cabinet mtg

LX-

Nut ; convection air duct upper, oven lamp mounting plate

and convection motor mtg

LX-

Nut

earthing

32000

Nut ; fan motor mtg

32000 Nut ; convection fan mtg

05300

Washer ; turntable coupling mtg

08000

Washer ; monitor switch lever mtg

08000 Washer ; convection fan mtg

10000

Washer ; convection fan mtg

08000

Washer ; power transformer mtg

000

Pin ; convection fan and pulley (A) mtg

000

Pin ;

pulley (B) mtg

04000 Ring ; turntable coupling mtg

HOW TO ORDER REPLACEMENT PARTS

To have your order filled promptly and correctly, please furnish the following information.

1. MODEL NUMBER

2. REF. NO.

3. PART NO.

4. DESCRIPTION

Page 49

-8470

R-8570

parts

marked parts on

lrst

been prepared

LISTED PART NO

USED PART

by side.

REF. NO.

c4 C5 etc

Cl0

D7 etc

etc

Cl50 etc 080

LISTED PART NO.

USED PART NO.

----

RC-

DREO

RC-

53N

RC-

04QDRE0

RC-

RH-

1 DREO

1 El

1 RH- I ZOO21 WREO RH- I X21 RH-TZ0029DREO

RH-TZA022DREO

143-A-l

RH-TZA025DREO

f 1 A

RH-TZA021 DREO

REF. NO.

R22 etc

R30 R55

etc

R84

R200 R204

LISTED PART NO.

USED PART NO.

NDREO

RD-

51 PDREO

SD-

51 J

RR-

21 PDREO

RD-

21 J

DZ277 PDREO

RR-

53DDRE0

53J

RR- DZ471

RD- ST

RR-

SERVICE INFORMATION FOR CONTROL UNIT

1st

have

and

So, please

LSI,

Remove

and

PWB

open Its pin nos

and 52

LSI.

C65

Page 50

R-8470 R-8570

PARTS

2 /

Page 51

R-8470 R-8570

2 3 4

Page 52

R-8470 R-8570

Page 53

R-8470 R-8570

DOOR

ASSEMBLY

MISCELLANEOUS

6-3

Trans.

Page 54

R-8470 R-8570

General:

Connect:

FIXING PROCEDURE OF CORD ANCHORAGE

As for the above subject, sometime it may cause to have wrong fixing about two pieces of cord anchorage unit. But this cord anchorage is an important part for the safety, therefore it must be fixed correctly and firmly.

The cord anchorage which is used to secure the mains supply cord can be fixed in two different ways.

If you fix them

shown in Figure 2, the mains supply cord will not be secured firmly.

Therefore, make sure to fix them as shown in figure 1.

BFO

SUPPLY

ANCHORAGE

Figure 1. Correct Fixing

2. Wrong Fixing

‘86

SHARP CORP. (9N0.75E) Printed in Japan