Sharp R23-004 Schematic

SER VICE MANUAL

SY911R23ATH/

COMMERCIAL

MICROWAVE OVEN

R-22AM R-23AM R-23AT

1800W/R-23AT

x 2

MODELS

R-22AM R-23AM R-23AT

R-23AT

In interests of user-safety the oven should be restored to its original condition and only parts identical to those specified should be used.

TABLE OF CONTENTS

Page

CAUTION, MICROWAVE RADIATION....................................................................... INSIDE FRONT COVER

WARNING..........................................................................................................................................................1

SERVICING ...................................................................................................................................................... 2

PRODUCT SPECIFICATIONS ......................................................................................................................... 5

GENERAL INFORMATION................................................................................................................................5

APPEARANCE VIEW ....................................................................................................................................... 6

OPERATION SEQUENCE................................................................................................................................ 7

FUNCTION OF IMPORTANT COMPONENTS ................................................................................................ 9

TROUBLESHOOTING GUIDE ........................................................................................................................10

TEST PROCEDURE ........................................................................................................................................12

TOUCH CONTROL PANEL ASSEMBLY ........................................................................................................20

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ........................................................... 31

MICROWAVE MEASUREMENT .................................................................................................................... 38

TEST DATA AT A GLANCE ........................................................................................................................... 39

WIRING DIAGRAM ......................................................................................................................................... 39

PICTORIAL DIAGRAM ................................................................................................................................... 41

CONTROL PANEL CIRCUIT ...........................................................................................................................42

PRINTED WIRING BOARD .............................................................................................................................45

PARTS LIST ................................................................................................................................................... 46

SHARP CORPORATION

R-22AM R-23AM R-23AT

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 microwave energy absorbing load attached. Never look into an open waveguide or antenna while the device is energized.

VARNING

MICKROVAGSSTRALING

Personal får inte utsättas för mikrovågsenergi som kan ustrala från magnetronen eller andre mikrovågsalstrande anordningar om dessa är felanslutna eller används på fel sätt. Alla in-och utgångsanslutningar för mikrovågor, vagledare, flänsar och packningar måste vara fast anslutna. Mikrovågsgeneratorn får inte arbeta utan att absorberande belastning är ansluten. Titta aldrig in i ën öppen vågledare eller antenn när mikrovågsgeneratorn är påkopplad eller laddad.

VAROITUS

MIKROAALTOSÄTELYÄ

Käyttäjä ei saa joutua alttiiksi mikroaaltoenergialle, jota voi säteillä magnetronista tai muusta mikroaaltoja kehittävästä laitteesta, jos sitä käytetään tai jos se kytketään väärin. Kaikkien mikroaaltoliitäntöjen sekä syöttö-että ulostulopuolella, aaltoputkien laippojen ja tiivisteiden tulee olla varmistettuja. Mikroaaltouunnia ei koskaan saa käyttää ilman kuormaa jossa mikroaaltoenergiaa kuluu. Avoimeen aaltoputkeen tai antenniin ei koskaan saa katsoa virran ollessa kytkettynä.

ADVARSEL

MIKROBØLGESTRÅLING

Personell må ikke utsettes for mikrobølge-energi som kan utståles fra magnetronen eller andre mikrobølge-generende deler dersom apparatet feilbetjenes eller blir feiltikoplet. Alle inn-og ut-tilkoplinger i forbindelse med mikrobølge-strålingen, bølgeledere, flenser og tetningsringer/pakninger må festes ordentlig. Aldri bruk apparatet med mindre en mikrobålge-absorberende last er plassert i ovnsrommet. Aldri se direkte inn i en åpen bølgeleder eller antenne imens apparatet er strømførende.

ADVARSEL

MIKROBØLGEBESTRÄLING

Man bør ikke udsætte sig for mikrobølgebestråling fra magnetronen eller andre mikrobølgefrembringende anordninger, hvilket kan ske hvis apparatet er forkert tilsluttet eller bruges forkert. Alle mikrobølgeindgange og-udgange, bølgeledere, flanger og tætningsstrimler må være forsvarligt udført. Anvend aldrig ovnen uden en mikrobølgesabsorberende anordning. Se aldrig ind i en åben bølgeleder eller antenne, mens ovnen er i brug.

SERVICE MANU AL

COMMERCIAL MICROWAVE OVEN

R-22AM/ R-23AM/ R-23AT

GENERAL IMPORTANT INFORMATION

This Manual has been prepared to provide Sharp Corp. Service engineers with Operation and Service Information.

It is recommended that service engineers carefully study the entire text of this manual, so they will be qualified to render satisfactory customer service.

SERVICING

PRODUCT SPECIFICATIONS

GENERAL INFORMATION

APPEARANCE VIEW

R-22AM R-23AM R-23AT

CAUTION MICROWAVE RADIATION DO NOT BECOME EXPOSED TO RADIATION FROM THE MICROWAVE GENERATOR OR OTHER PARTS THAT CONDUCT MICROWAVE ENERGY.

WARNING

Note: The parts marked "*" are used in voltage more

than 250V. (Parts List)

Anm: Delar märket med "*" har en spänning

överstigande 250V.

Huom: Huolto-ohjeeseen merkitty "tähdella" osat joissa

jännite on yli 250 V.

Bemerk: Deler som er merket "asterisk" er utsatt for

spenninger over 250V til jord.

Bemærk: "Dele mærket med stjerne benyttes med højere

spænding end 250 volt.

WARNING

OPERATING SEQUENCE

FUNCTION OF IMPORTANT COMPONENTS

TROUBLESHOOTING GUIDE AND TEST PROCEDURE

TOUCH CONTROL PANEL

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE

MICROWAVE MEASUREMENT

Never operate the oven until the following points are ensured. (A) The door is tightly closed. (B) The door brackets and hinges are not defective. (C) The door packing is not damaged. (D) The door is not deformed or warped. (E) There is not any other visible damage with the oven.

Servicing and repair work must be carried out only by trained service engineers.

All the parts marked "*" on parts list are used at voltage more than 250V.

Removal of the outer wrap gives access to potential above 250V.

All the parts marked "∆" on the parts list may cause undue microwave exposure, by themselves, or when they are damaged, loosened or removed.

SHARP CORPORATION

OSAKA, JAPAN

TEST DATA AT A GLANCE

WIRING DIAGRAM

PARTS LIST

R-22AM R-23AM R-23AT

SERVICING

WARNING TO SERVICE PERSONNEL

GB Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts will result

in electrocution. High voltage capacitor, High voltage transformer, Magnetron, High voltage rectifier assembly, High voltage fuses, High voltage harness.

REMEMBER TO CHECK 3D

1) Disconnect the supply.

2) Door opened, and wedged open.

3) Discharge two high voltage capacitors.

WARNING: AGAINST THE CHARGE OF THE TWO

HIGH-VOLTAGE CAPACITORS

The two high-voltage capacitors remains charged about 60 seconds after the oven has been switched off. Wait for 60 seconds and then short-circuit the connection of the two high-voltage capacitors (that is, of the connecting lead of the high-voltage rectifier) against the chassis with the use of an insulated screwdriver.

Sharp recommend that wherever possible fault-finding is carried out with the supply disconnected. It may in, some cases, be necessary to connect the supply after the outer case has been removed, in this event carry out then disconnect the leads to the primary of the two High voltage transformers. Ensure that these leads remain isolated from other components and the oven chassis. (Use insulation tape if necessary.) When the testing is completed carry out checks and reconnect the leads to the primary of the two High voltage transformers.

NL Magnetronovens bevatten circuits die een zeer hoge spanning en stroom kunnen voortbrengen. Contact met de

volgende onderdelen kan elektrocutie tot gevolg hebben. Hoogspanningscondensator, hoogspanningstransformator, magnetron, hoogspanningsgelijkrichter, hoogspannings kabelboom.

3D checks and

REMEMBER TO CHECK 4R

1) Reconnect all leads removed from components during testing.

2) Replace the outer case (cabinet).

3) Reconnect the supply.

4) Run the oven. Check all functions. Microwave ovens should not be run empty. To test for the

presence of microwave energy within a cavity, place a cup of cold water on the oven turntable, close the door and set the power to HIGH and set the microwave timer for one (1) minute. When the one minute has elapsed (timer at zero) carefully check that the water is now hot. If the water remains cold carry out

3D checks and re-examine the connections to the compo-

nent being tested. When all service work is completed, and the oven is fully

assembled, the microwave power output should be checked and a microwave leakage test should be carried out.

VERGEET DE VOLGENDE 3 STAPPEN NIET

1) Haal de stekker uit het stopcontact.

2) Open de deur en zorg ervoor dat hij niet dicht kan vallen.

3) Ontlaad de hoogspanningscondensator.

PAS OP VOOR DE ELECTRISCHE LADING VAN DE HOOGSPANNINGSCONDENSATOR

De hoogspanningscondensator blijft nog ongeveer 60 seconden lang opgeladen, nadat de oven is uitgeschakeld. Wacht 60 seconden voordat u de verbinding van de hoogspannings-condensator (m.a.w. de verbindingsdraad van de hoogspanningsgelijkrichter) met een geïsoleerde schroevedraaier kortsluit tegen het chassis.

Sharp beveelt ten sterkste aan dat, voor zover mogelijk, defecten worden opgespoord wanneer de stekker uit het stopcontact is gehaald. Soms is het nodig om de stroomtoevoer weer tot stand te brengen nadat de buitenmantel verwijderd is. Herhaal dan de bovengenoemde 3 stappen en haal de electrische draden uit de primaire zijde van de vermogenstransformator. Zorg ervoor dat deze draden geïsoleerd blijven van andere elementen en van het chassis van de oven. (Gebruik zo nodig isolatieband.) Wanneer de test is uitgevoerd, herhaalt u de bovenstaande 3 stappen en verbindt u de electrische draden weer aan de primaire zijde van de vermogenstransformator.

VERGEET DE VOLGENDE 4 STAPPEN NIET

1) Sluit de draden weer aan diezijn losgehaald voor de test.

2) Plaats de buitenmantel weer om het toestel heen (kabinet).

3) Stop de stekker weer in het stopcontact.

4) Zet de oven aan. Controleer alle functies. Magnetronovens mogen niet leeg aangezet worden. Om te

controleren of er microgolf-energie binnen de oven wordt geproduceerd, plaatst u een mok met koud water op de draaitafel van de oven, sluit de deur, zet de oven op HIGH en stelt de klok van de magnetron in op twee (2) minuten. Wanneer de twee minuten voorbij zijn (klok staat op nul), controleert u voorzichtig of het water heet is. Indien het water nog steeds koud is, herhaalt u de allereerste drie stappen en controleer nogmaals de aansluitingen naar de geteste onderdelen.

Wanneer alle reparaties zijn uitgevoerd en de oven weer in elkaar is gezet, moet de het magnetronvermogen worden gecontroleerd en moet worden gecontroleerd of er geen microgolflekkage is.

R-22AM R-23AM R-23AT

E Los hornos de microondas contienen circuitos eléctricos capaces de producir voltajes de alta tensión y descargas

eléctricas. Para evitar el riesgo de electrocución, absténgase de tocar los siguientes componentes: condensador de alta tensión, transformador de alta tensión, magnetrón, dispositivo del rectificador de alta tensión y arnés de alta tensión.

RECUERDE LA COMPROBACION 3D

1) Desconecte la alimentación.

2) Deje la puerta abierta y calzada.

3) Descargue el condensador de alto voltaje.

ADVERTENCIA SOBRE LA CARGA DEL CONDENSADOR DE ALTO VOLTAJE

El condensador de alto voltaje permanece cargado unos 60 segundos después de haber apagado el horno. Espere 60 segundos y luego ponga en cortocircuito la conexión del condensador de alto voltaje (esto es, del conductor de conexión del rectificador de alto voltaje) al chasis con un destornillador de mango aislado.

Se recomienda encarecidamente que siempre que sea posible la localización de fallos se realice con la alimentación desconectada. Puede ser que en algunos casos sea necesario conectar la alimentación después de haber retirado la carcasa exterior. En este caso, realice las comprobaciones 3D y luego desconecte los conductores del primario del transformador de alimentación. Asegúrese de que estos conductores permanezcan aislados de otros componentes y del chasis del horno. (Use cinta aislante si es necesario). Cuando termine la prueba efectúe las comprobaciones 3D y reconecte los conductores al primario del transformador de alimentación.

RECUERDE LA COMPROBACION 4C

1) Conecte todos los componentes desconectados de los componentes durante la prueba.

2) Coloque la carcasa exterior (cabina).

3) Conecte la alimentación.

4) Compruebe todas sus funciones despues de poner en marcha el horno.

Los hornos de microondas no deben funcionar vacíos. Para comprobar la presencia de energía de microondas dentro de una cavidad, coloque una taza de agua fría en el plato giratorio del horno, cierre la puerta y ponga la potencia en HIGH (alta) y coloque el temporizador en dos (2) minutos. Cuando transcurran los dos minutos (temporizador a cero) compruebe cuidadosamente que el agua se ha calentado. Si el agua permaneciese fría, efectúe las comprobaciones 3D y vuelva a examinar las conexiones de los componentes que han sido probados.

Cuando hay a terminado la intervención en el equipo y el horno haya sido ensamblado de nuevo completamente, deberá comprobar la potencia de salida de microondas y realizar una prueba de fugas de microondas.

SV Mikrovågsugnar innehåller kretsar som producerar mycket höga spänningar och strömmar.

Kontakt med följande komponenter kan leda till dödsfall: Högspänningskondensator, transformator, magnetron, högspännings likriktare, högspännings kablage.

KOM IHÅG ATT KONTROLLERA 3 STEG

1) Koppla från strömkällan.

2) Öppna dörren på glänt.

3) Ladda ur högspänningskondensatorn.

KOM IHÅG ATT KONTROLLERA 4 STEG

1) Anslut alla ledningar som använts vid testning

2) Sätt tillbaka ytterhöljet.

3) Anslut strömkällan på nytt.

4) Sätt på ugnen. Kontrollera alla funktioner.

VARNING FÖR LADDNINGEN I HÖGSPÄNNINGSKONDENSATORN

Högspänningskondensatorn är laddad i 60 sekunder efter det att ugnen stängts av. Vänta 60 sekunder och korislut sedan kondensatoms anslutning (dvs anslutningen till högspänningslikriktaren) till chassiet med hjälp av en isolerad skruvmejsel.

Sharp rekommenderar att felsökning sker med strömmen fränkopplad. Ibland kan det var nödvändigt att koppla på strömmen efter det att höljet avlägsnats, utför da 3 Steg kontrollen och koppla sedan från ledarna till transformatorns

Mikrovågsugnar får inte användas tomma. Kontrollera mikrovågsstrålningen i olika delar av ugnen genom att placera en kopp med kallt vatten på ugnens tallrik, stäng dörren, ställ in HIGH och ställ in 2 minuter på timern. När två minuter har gått (timem visar 0) kontrollerar du om vattnet är varmt. Om vattnet fortfarande är kallt utför Du 3 steg kontroller och kontrollerar anslutningarna till varje enskild komponent på nytt.

När all service är klar och ugnen ihopskruvad skall ugnens uteffekt och eventuellt mikrovågsläckage kontrolleras.

primärsida. Se till att ledarna är isolerade från andra komponenter och chassiet. (Använd isoleringsband om det behövs). När Du testat färdigt utför Du 3 Steg kontrollen och ansluter ledningarna till transformatorns primärsida igen.

R-22AM R-23AM R-23AT

I I forni a microonde contengono un circuito elettrico in grado di generare tensioni e correnti estremamente elevate.

L’eventuale contatto con i seguenti componenti può causare la folgorazione: condensatore ad alta tensione; trasformatore ad alta tensione; magnetron; rettificatore alta tensione; cablaggio ad alta tensione.

TRE OPERAZIONI IMPORTANTI PER INCOMINCIARE

1) Scollegare l'alimentazione elettrica.

2) Verificare che la porta sia bloccata in posizione aperta.

3) Scaricare il condensatore ad alta tensione.

ATTENZIONE AL CONDENSATORE AD ALTA TENSIONE: PUO ESSERE CARICO

Il condensatore ad alta tensione rimane carico per circa 60 secondi dopo lo spegnimento del forno. Occorre quindi spettare 60 secondi prima di cortocircuitare, utilizzando un cacciavite con impugnatura isolata, il collegamento del condensatore ad alta tensione (cioè del conduttore di collegamento del raddrizzatore ad alta tensione) sul telaio del forno.

Sharp raccomanda, nei limiti del possibile, che la ricerca dei guasti avvenga in assenza di alimentazione elettrica. In alcuni casi tuttavia, può essere necessario alimentare l'apparecchio dopo aver rimosso la scatola esterna. In questo caso eseguire i tre controlli sopra citati e quindi scollegare i connettori dal primario del trasformatore. Assicurarsi che tali connettori non vengano a contatto con altri componenti, ne con il telaio del forno (fare uso, se necessario, di nastro isolante). Al termine dell'intervento, eseguire nuovamente i tre controlli e ricollegare i conduttori al primario del trasformatore.

QUATTRO VERIFICHE IMPORTANTI DA NON DIMENTICARE

1) Ricollegare tutti i conduttori staccati dai vari componenti durante l'intervento.

2) Rimontare la scatola esterna.

3) Ripristinare l'alimentazione elettrica.

4) Rimettere in funzione il forno. Controllare tutte le funzioni.

I forni a microonde non devono mai funzionare a vuoto . P er verificare la presenza di energia da microonde all'interno di una cavitá, mettere una tazza di acqua fredda sul piatto rotante del forno , chiudere la porta, regolare la potenza su HIGH ed impostate il temporizzatore su due (2) minuti. Trascorsi i due minuti (temporizzatore a zero), controllare accuratamente che ora l'acqua sia calda. Se l'acqua è rimasta fredda, eseguire i tre controlli iniziali e verificare nuovamente i collegamenti del componente in questione.

Dopo aver portato a termine le operazioni di manutenzione e rimontato il forno, è necessario controllare la potenza delle microonde emesse ed eseguire un test per verificare che non vi sia alcuna dispersione.

1800W/R-23AM

/100%

/ 50%

/ 20%

/ 10%

R-23AM

PRODUCT DESCRIPTION

SPECIFICATION

ITEM DESCRIPTION

Power Requirements 230 Volts

50 Hertz

Single phase, 3 wire earthed Power Comsumption Power Output

Case Dimensions Width Height Depth

Cooking Cavity Dimensions Width Height Depth

Control Complement for R-23AT Touch Control System

2.4 kW Approx. 11 A [R-22AM] / 2.9 kW Approx. 13 A [R-23AM, R-23AT]

1500 W [R-22AM]/ 1800 W [R-23AM/23AT] nominal of RF microwave energy

(measured by method of IEC 60705)

Operating frequency 2450 MHz

510mm 335 mm 470mm

330 mm 180 mm 330mm

The combination of cooking time and microwave power

The oven can be programmed a series of up to 3 cookling stages.

The combination of microwave power and cooking time that can be input as

folllows.

Cooking Sequence Micrwave power levelthat can be iused. Cooking time that can be iused.

1 Stage only 0-100% Max. 30 minutes

0-40% all stages Max. 30 minutes any stages

2 or 3 Stage

50-100% Max. 30 minutes for 3 stages

R-22AM R-23AM R-23AT

Max. 60 minutes for 2 stages Max. 90 minutes for 3 stages

NOTE:If the oven used with the power level above 40% on any stage, the

maximum cooking time is 30 minutes in total.

Microwave Power level

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

MANUAL / REPEAT key, NUMBER keys

POWER LEVEL key, STOP / CLEAR key

START Key, DOUBLE QUANTITY key

DEFROST key, SET key

CHECK key, VOLUME key

Control Complement for R-22AM/23AM

Electronic Timer (0 - 30 minutes)

Microwave Power level

100% 50% 20% 10%

MICROWAVE POWER SETTING buttons

START button Set Weight Approx. 33 kg

GENERAL INFORMATION

WARNING

THIS APPLIANCE MUST BE EARTHED

IMPORTANT

THE WIRES IN THIS MAINS LEAD ARE COLOURED IN ACCORDANCE WITH THE FOLLOWING CODE:

GREEN-AND-YELLOW : EARTH BLUE : NEUTRAL BROWN : LIVE

R-22AM R-23AM R-23AT

OVEN

1. Control panel

2. Hole for safety door latches

3. Ceramic floor

4. Splash cover

5. Oven light

6. Air intake filter

7. Air intake openings

8. Oven cavity

9. Door seals and sealing surfaces

10. Door hinges

11. Oven door with see-through window

12. Door safety latches

13. Door handle.

14. Outer cabinet

15. Removable cover over oven light bulb

16. Air vent openings

17. Power supply cord 18 Mounting plate 19 Screw for mounting plate

DISPLAY AND INDICATORS for R-23AT

Check indicators after the oven starts to confirm the oven is operating as desired.

1. Cook indicator This indicator shows cooking in progress.

2. Memory number indicator

3. Defrost indicator

4. Check mode indicator

5. Power level display

6. Digital display

7. Filter indicator

8. Double quantity mode indicator

9. 3rd. stage indicator

10. 2nd. stage indicator

11. 1st. stage indicator

OPERATING KEYS

12. DOUBLE QUANTITY key

13. DEFROST key

14. NUMBER keys

15. MANUAL/ REPEAT key

16. STOP/CLEAR key

17. POWER SLEVEL key

18. START key

19. SET key

20. VOLUME key

21. CHECK key

15 17

APPEARANCE VIEW

NUMBER

1 2 3

DOUBLE

x 2

DEF

CHECK

FILTER

679

AUTO TOUCH CONTROL PANEL

POWER

1 2 3 4 5 6 7 8 9 0

DISPLAY AND INDI-

CATORS for R-22AM,

R-23AM

Check indicators after the oven starts to con-

firm the oven is operating as desired.

1. Cook indicator This indicator shows cooking in progress.

2. Digital display

3. Microwave power level display

OPERATING KEYS

4. HIGH 100%

5. MEDIUM 50%

6. MED LOW 20%

7. DEFROST 10%

8. ELECTRONIC TIMER

18 20

Rotate the control to enter cooking time.

9. START button

/100%

/ 50%

/ 20%

/ 10%

MICROWAVE POWER LEVEL buttons

POWER

INSTALLATION INFORMATION

When this commercial microwave oven is installed near other commercial electrical appliances, connect a lead wire to each equivalent potential terminal with equipotential marking between them (insert a lead wire between a washer and an earth angle, and screw them), as shown in Fig. A-1, to make sure that they are at equivalent potential. If any lead wire is not connected between them, when person touch them he/she will get a electric shock.

COMMERCIAL MICROWAVE OVEN OTHER COMMERCIAL 

Equipotential marking

Lead wire

Screw

Washer

Earth angle (Equivalent potential terminal)

Lead wire

Figure A-1

ELECTRICAL APPLIANCE

Equivalent  potential terminal

OPERATION SEQUENCE

R-22AM R-23AM R-23AT

Closing the door activates all door interlock switches (1st latch switch, 2nd latch switch, 3rd latch switch and stop switch).

IMPORTANT

When the oven door is closed, the monitor switch contacts COM-NC must be open. When the microwave oven is plugged in a wall outlet (230 volts, 50Hz), the line voltage is supplied to the point A5+A7 in the control panel through the noise filter.

Figure O-1 on page 39

1. The digital display shows .

IDLE CONDITION

When the door is opened, the contacts of the 1st. latch switch SW1, 2nd. latch switch SW2, 3rd. latch switch SW3 and stop switch SW5 open, initiating the following:

Figure O-2 on page 40

1. A signal is input to the control unit energizing the coil of shut-off relay RY-1.

2. The shut-off relay RY-1 contacts close completing circuits to turn on the oven lamp, blower motor and stirrer motors.

3. If the door remains open, 60 seconds later the control unit de-energizes shut-off relay RY-1 turning off the oven lamp, blower motor and stirrer motors.

When the door is closed, the contacts of the 1st. latch switch SW1, 2nd. latch switch SW2, 3rd. latch switch SW3 and stop switch SW5 close. With the closing of the stop switch SW5 contacts, an additional circuit is provided which will permit the operation of the oven when one of the touch pads is depressed. Since the control is enabled through the stop switch SW5, the door must be closed before the touch pads will be effective. When the door is closed, a full 60 second IDLE condition is always provided for selecting and pressing the desired touch pads. A 60 second IDLE condition will also follow the end of each cook cycle.

the two high voltage transformers. The voltage is converted to about 3.3 volts A.C. output on the filament winding and high voltage of approximately 2000 volts A.C. on the secondary winding.

2. The filament winding voltage (3.3 volts) heats the magnetron filament and the high voltage (2000 volts) is sent to the voltage doubling circuit, where it is doubled to negative voltage of approximately 4000 volts D.C..

3. The 2450 MHz microwave energy produced in the magnetron generates a wave length of 12.24 cm. This energy is channelled through the waveguide (transport channel) into the oven cavity, where the food is placed to be cooked.

4. When the cooking time is up, a signal tone is heard and the relays RY3+RY4 (for R-23AT)/ RY2+RY3 (for R22AM/23AM) go back to their home position. The circuits to the high voltage transformers T1+T2. The relay RY1 remains and oven lamp, blower motor and stirrer motors work for 1 minute.

5. When the door is opened during a cook cycle, the switches come to the following condition.

CONDITION DURING DOOR OPEN

SWITCH CONTACT COOKING 1st latch switch COM-NO Closed Open Monitor switch COM-NC Open Closed 2nd latch switch COM-NO Closed Open Stop switch COM-NO Closed Open 3rd latch switch COM-NO Closed Open

(NO COOKING)

The circuits to the high voltage transformers T1+T2 are cut off when the 1st latch, 2nd latch, 3rd latch and stop switches SW1+SW2+SW3+SW5 are made open. The blower motor BM, stirrer motors and oven lamp remains on even if the oven door is opened after the cooking cycle has been interrupted, because the relay RY1 stays closed. Shown in the display is the remaining time, but the program is cancelled if the oven is not started within 3 minutes.

MICROWAVE COOKING CONDITION

for R-23AT

Touch MANUAL/ REPEAT key and enter a desired cooking time with the touching NUMBER key. And then touch START key.

Function sequence Figure O-3 on page 40

CONNECTED COMPONENTS RELAY Oven lamp/ Blower motor/ Stirrer motors RY1 High voltage transformer T1 RY3 High voltage transformer T2 RY4

for R-22AM/23AM

Enter a desired cooking time with the turning ELECTRONIC TIMER knob. And then push STARTbutton.

Function sequence Figure O-3 on page 40

CONNECTED COMPONENTS RELAY Oven lamp/ Blower motor/ Stirrer motors RY1 High voltage transformer T1 RY2 High voltage transformer T2 RY3

1. The line voltage is supplied to the primary winding of

6. MONITOR SWITCH CIRCUIT The monitor switch SW4 is mechanically controlled by oven door, and monitors the operation of the 1st latch switch SW1.

6-1. When the oven door is opened during or after the

cycle of a cooking program, the 1st, 2nd, 3rd latch and stop switches SW1+SW2+SW3+SW5 must open their contacts first. After that the contacts (COM-NC) of the monitor switch SW4 can be closed.

6-2. When the oven door is closed, the contacts (COM-

NC) of the monitor switch SW4 must be opened first. After that the contacts (COM-NO) of the 1st, 2nd, 3rd latch and stop switches SW1+SW2+SW3+SW5 must be closed.

6-3. When the oven door is opened and the contacts of the

1st latch switch SW1 remain closed, remains closed, the fuse F2 F6.3A will blow, because the monitor switch is closed and a short circuit is caused.

MICROWAVE VARIABLE COOKING (for R-23AT)

When the microwave oven is preset for variable cooking power, the line voltage is supplied to the high voltage

R-22AM R-23AM R-23AT

transformers T1+T2 intermittently within a 48 second time base through the contacts of the relays RY3+RY4. The following levels of microwaves power are given.

 48 sec. ON Number key   44sec. ON Number key 9  40 sec. ON Number key 8  36 sec. ON Number key 7  32 sec. ON Number key 6  26 sec. ON Number key 5  22 sec. ON Number key 4  16 sec. ON Number key 3  12 sec. ON Number key 2  8 sec. ON Number key 1  0 sec. ON Number key 0

TWO MAGNETRON OPERATION SYSTEM

Two magnetrons MG1+MG2 are equipped in order to get higher microwave power output. The primary windings of the high voltage transformers T1+T2 are connected so that each magnetron can be oscillated alternatively according to the frequency of the power supply. Refer to the Figure B-1 and B-2.

T2: HIGH VOLTAGE TRANSFORMER

(REAR)

H. V. FUSE H. V. FUSE

H. V. RECTIFIER

MG2: MAGNETRON (LOWER)

C2: H.V. CAPACITOR

H. V. RECTIFIER

Figure B-1. High Voltage Circuit

MG1: MAGNETRON (UPPER)

T1: HIGH VOLTAGE TRANSFORMER

(FRONT)

C1: H.V. CAPACITOR

NOTE: The ON/OFF time ratio does not exactly corre-

spond to the percentage of microwave power, because approx. 3 seconds are needed for heating up the magnetron filament.

MICROWAVE VARIABLE COOKING (for R-22AM and R-23AM)

When the microwave oven is preset for variable cooking power, the line voltage is supplied to the high voltage transformers intermittently within a 48 second time base through the contacts of the relays RY2+RY3. The following levels of microwaves power are given.

 48 sec. ON  100%   26sec. ON  50%  12 sec. ON  20%  8 sec. ON  10%

NOTE: The ON/OFF time ratio does not exactly corre-

spond to the percentage of microwave power, because approx. 3 seconds are needed for heating up the magnetron filament.

OPERATION OF MAGNETRON

COMMERCIAL FREQUENCY (50HZ)

POWER OUTPUT BY MAGNETRON T1

POWER OUTPUT BY MAGNETRON T2

Figure B-2. Operation of Magnetron

FUNCTION OF IMPORTANT COMPONENTS

R-22AM R-23AM R-23AT

DOOR OPEN MECHANISM

1. The door release lever is pulled.

2. The upper latch head is lifted up by the linked door release lever.

3. The head lever is lifted up by the door release lever.

4. The joint lever is lifted up by the head lever.

5. The lower latch head is lifted up by the joint lever.

6. Now both latch heads are lifted up, so they can be released from the latch hook.

7. Now the door can be opened.

Door release lever

Joint lever

Head lever

Latch head

SW4: Monitor switch

Latch hook

SW2: 2nd. latch switch SW1: 1st. latch switch

SW5: Stop switch

SW3: 3rd. latch switch

Figure D-1. Door Open Mechanism

1ST LATCH SWITCH SW1, 2ND LATCH SWITCH SW2, 3RD LATCH SWITCH SW3 AND STOP SWITCH

1. When the oven door is closed, the contacts COM-NO must be closed.

2. When the oven door is opened, the contacts COM-NO must be opened.

SW5

MONITOR SWITCH SW4

The monitor switch SW4 is activated (the contacts opened) the upper latch head and switch lever A while the door is closed. The switch is intended to render the oven inoperative by means of blowing the fuse F2 F6.3A when the contacts of the 1st latch switch SW1 fail to open when the door is opened.

Function

1. When the door is opened, the monitor switch SW4 contacts close (to the ON condition) due to their being normally closed. At this time the 1st latch switch SW1 is in the OFF condition (contacts open) due to their being normally open contact switches.

2. As the door goes to a closed position, the monitor switch SW4 contacts are opened and 1st latch switch SW1 contacts are closed (On opening the door, each of these switches operate inversely.)

3. If the door is opened and the 1st latch switch SW1 contacts fail to open, the fuse F2 F6.3A blows simultaneously with closing of the monitor switch SW4 contacts.

CAUTION:BEFORE REPLACING A BLOWN FUSE F2

F6.3A TEST THE 1ST LATCH SWITCH SW1, MONITOR SWITCH SW4 AND MONITOR RESISTOR R1 FOR PROPER OPERATION. (REFER TO CHAPTER “TEST PROCEDURE”).

MONITOR RESISTOR R1

The monitor resistor R1 prevents the fuse F2 F6.3A 250V bursting when the fuse F 2 F6.3A 250V blows due to the operation of the monitor switch SW4.

NOISE FILTER

The noise filter assembly prevents radio frequency interference that might flow back in the power circuit.

WEAK POINT F1

If the wire harness or electrical components make a shortcircuit, this weak point F1 blows to prevent an electric shock or fire hazard.

FUSE F2 F6.3A 250V

1. If the wire harness or electrical components are shortcircuited, this fuse blows to prevent an electric shock or fire hazard.

2. The fuse F2 also blows when 1st latch switch SW1 remains closed with the oven door open and when the monitor switch closes.

FUSE(S) F3, F4 M8A

If the wire harness or the high voltage transformers T1, T2 are short-circuited, these fuses F3 and /or F4 blow to prevent an electric shock or fire hazard.

HIGH VOLTAGE FUSE(S) F5, F6

The high voltage fuse blows when the high voltage rectifier or the magnetron is shorted.

MAGNETRON TEMPERATURE FUSES TF1, TF2

The temperature fuses TF1, TF2 located on the top of the upper and lower waveguide, are designed to prevent damage to the magnetrons MG1, MG2. If an over heated condition develops in the tube due to blower motor failure, obstructed air ducts, dirty or blocked air intake, etc., the circuit to the magnetrons are interrupted. Under normal operation, the temperature fuses remains closed. However, when abnormally high temperatures are generated within the magnetrons, the temperature fuses will open at 150˚C causing the microwave energy to stop. The defective temperature fuses must be replaced with new rated ones.

OVEN TEMPERATURE FUSE TF4

The temperature fuse TF4, located on the side of the exhaust duct assembly, is designed to prevent damage to the oven by fire. If the food load is overcooked, by either error in cook time or defect in the control unit, the temperature fuse will open. Under normal operation, the oven temperature fuse remains closed. However, when abnormally high temperatures are generated within the oven

R-22AM R-23AM R-23AT

cavity, the oven temperature fuse will open at 120˚C, causing the oven to shut down. The defective temperature fuse must be replaced with new rated one.

BLOWER MOTOR TEMPERATURE FUSE TF3

This temperature fuse TF3 protects the blower motor against overheating. If its temperature goes above 120˚C because the blower motor is stalled or the ventilation openings are blocked, the contacts of the temperature fuse will open. The line voltage to the control unit will be cut off and the operation of the oven will be stopped. The defective temperature fuse must be replaced with a new one.

OVEN THERMISTOR (1)

The thermistor is a negative temperature coefficient type. The temperature in the exhaust duct is detected through the resistance of the thermistor. If the temperature is high, the control panel will display “EE7” and the oven will stop to avoid overheating and catching fire. If the thermistor is open, the control panel will display "EE6" and the oven will stop.

OVEN THERMISTOR (2)

This thermistor detects temperature of the oven cavity bottom plate. The thermistor is a negative temperature coefficient type. The temperature is detected through the resistance of the thermistor. If the temperature is high, the control will display “EE17” and the oven will stop.

MAGNETRON THERMISTOR

The thermistor is a negative temperature coefficient type. The air temperature around the upper magnetron is detected through the resistance of the thermistor. If the temperature is high, the control panel will display "EE17" and the oven will stop to protect the lower magnetron against overheat. If the oven thermistor (2) and the magnetron thermistor are open at the same time, the control panel will display "EE16" and the oven will stop.

BLOWER MOTOR BM

The blower motor BM drives a blade which draws external cool air into the oven. This cool air is directed through the air vanes surrounding the magnetrons and cools the magnetrons. This air is channelled through the oven cavity to remove steam and vapours given off from the heating foods. It is then exhausted through the exhausting air vents at the oven cavity.

STIRRER MOTORS SM

The upper and lower stirrer motors SM drive stirrer antennas to stir the microwave radiation from the upper and lower waveguides.

OVEN LAMP OL

The oven cavity light illuminates the interior of the oven so that food being cooked can be examined visually through the door window without having to open the door. The oven lamp is on during the cooking cycle and idle condition.

TROUBLESHOOTING GUIDE

When troubleshooting the microwave oven, it is helpful to follow the Sequence of Operation in performing the checks. Many of the possible causes of trouble will require that a specific test be performed. These tests are given a procedure letter which will be found in the “Test Procedure”section. IMPORTANT: If the oven becomes inoperative because of a blown fuse F2 F6.3A in the 1st latch switch SW1 - monitor

switch SW4 - monitor resisitor R1 circuit, check the 1st latch switch SW1, monitor switch SW4 and monitor resistor R1 before replacing the fuse F2 F6.3A

A ABBCC DDEEEEEFFGHI I I I JKKKL LN M OQQQR P

 KEY UNIT [for R-23AT], or SWITCH UNIT [for R-22AM/23AM] Temperature of oven thermistor (2) is high. Temperature of oven thermistor (1) is high. Temperature of magnetron thermistor is high. Due to programme lock Over the max. cooking time [for R-23AT] No power at wall outlet HOME FUSE or BREAKER Mis adjustment of switches FOIL PATTERN RELAY RY-4 [for R-23AT], RY3 [for R22AM/23AM] RELAY RY-3 [for R-23AT], RY2 [for R-22AM/23AM] RELAY RY-1 TOUCH CONTROL PANEL Opened wire harness Shorted wire harness FUSE HOLDERS POWER SUPPLY CORD NOISE FILTER OVEN LAMP OR SOCKET HIGH VOLTAGE FUSE(S) F5, F6 BLOWER MOTOR BM STIRRER MOTORS SM OVEN THERMISTOR (2) OVEN THERMISTOR (1) MAGNETRON THERMISTOR MONITOR RESISTOR R1 OVEN TEMPERATURE FUSE TF4 B. MOTOR TEMPERATURE FUSE TF3 MAGNETRON TEMPERATURE FUSE TF2 MAGNETRON TEMPERATURE FUSE TF1 FUSE F6.3A F2 FUSE F13A F1 FUSE M8A F4 FUSE M8A F3 STOP SWITCH SW5 MONITOR SWITCH SW4  3RD. LATCH SWITCH SW3 2ND. LATCH SWITCH SW2  1ST. LATCH SWITCH SW1  H.V. CAPACITOR C2 H.V. CAPACITOR C1 H.V. WIRE HARNESS H.V. RECTIFIER ASSEMBLY FOR MG2 H.V. RECTIFIER ASSEMBLY FOR MG1 HIGH VOLTAGE TRANSFORMER T2 HIGH VOLTAGE TRANSFORMER T1 MAGNETRON MG2 MAGNETRON MG1

R-22AM R-23AM R-23AT

TESTPROCEDURE

AND

POSSIBLE CAUSE

DEFECTIVE PARTS

PROBLEM

“ . “ does not appear on display when power cord is plugged into

wall outlet.

Control panel can not accept key in.

Fuse F2 F6.3A blows when the door is opened. 

Home fuse blows when power cord is plugged into wall outlet. 

Weak point F1 blows when power cord is plugged into wall outlet.

Oven lamp, fan motor and stirrer motors do not work for 1 minute

when the door is opened or after cooking.

Fuse F2 F6.3A blows when power cord is plugged into wall outlet. 

Oven lamp does not light when door is opened. (Blower and stirrer

motors work)

Blower motor does not work when door is opened. (Oven lamp

lights and stirrer motors work)

“EE 1” (Magnetron MG1 failure) 

“EE 2” (Magnetron MG2 failure)

“EE 3” (Magnetron MG1 and MG2 failure) 

“EE 6” (Thermistor (1) failure) 

“EE 7” (Exhaust air temperature is high) 

“EE 9” (Exceeded max. heating time) for R-23AT

Oven lamp, blower motor and stirrer motors do not work. 

Oven lamp does not work. 

OFF

CONDITION

Blower motor does not work. 

Oven does not stop after end of cooking cycle. (Oven lamp, blower

motor and stirrer motors stop.)

Home fuse blows when starting the oven.

Oven goes into cook cycle but shuts down before end of cooking cycle. 

It passed more than 1 minute after cooking but oven lamp, blower

motor and stirrer motors do not stop.

“EE 16” (Thermistor of MG. and (2) are open.) 

“EE 17” (Magnetron temperature is high.) 

“EE 8” (Relay melt short)

Stirrer motors do not work.



ON

CONDITION

R-22AM R-23AM R-23AT

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

A MAGNETRON TEST

NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL WHILE THE OVEN IS IN OPERATION.

CARRY OUT 3D CHECKS. Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal. To test for an open circuit filament use an ohmmeter to make a continuity test between the magnetron

filament terminals, the meter should show a reading of less than 1 ohm. To test for short circuit filament to anode condition, connect ohmmeter between one of the filament

terminals and the case of the magnetron (ground). This test should be indicated an infinite resistance. If a low or zero resistance reading is obtained then the magnetron should be replaced.

MICROWAVE OUTPUT POWER (1 litre water load)

The following test procedure should be carried out with the microwave oven in a fully assembled condition (outer case fitted). Microwave output power from the magnetron can be measured by way of IEC 60705, i.e. it is measured by how much power the water load can absorb. 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 t/4.187 calorie is generated. On the other hand, if the temperature of the water with V(ml) rises ∆T (°C) during this microwave heating period, the calorie of the water is V x ∆T.

The formula is as follows;

P x t / 4.187 = V x ∆ T+ 0.55 x mc (T2-T0) P (W) = 4.187 x V x ∆T / t + 0.55 x mc (T2-T0)/t

Our condition for water load is as follows:

Room temperature (T0) ...... around 20°C Power supply Voltage.............. Rated voltage

Water load.....................................1000 g Initial temperature (T1) ...................... 10±1°C

Heating time28 sec. [R-22AM] / 23sec. [R-23AM/23AT] Mass of container (mc) .........330 g

T2............... Final temperature P = 150 x ∆T [R-22AM] / P = 180 x ∆T [R-23AM, R-23AT]

Measuring condition:

1. Container The water container must be a cylindrical borosilicate glass vessel having a maximum material thickness of 3 mm and an outside diameter of approximately 190 mm.

2. Temperature of the oven and vessel The oven and the empty vessel are at ambient temperature prior to the start the test.

3. Temperature of the water The initial temperature of the water is (10±1)°C.

4. Select the initial and final water temperature so that the maximum difference between the final water temperature and the ambient temperature is 5°C.

5. Select stirring devices and measuring instruments in order to minimize addition or removal of heat.

6. The graduation of the thermometer must be scaled by 0.1°C at minimum and be an accurate thermometer.

7. The water load must be (1000±5) g.

8. “t” is measured while the microwave generator is operating at full power. Magnetron filament heatup time is not included.

NOTE:The operation time of the microwave oven is “t + 3” sec. (3 sec. is magnetron filament heat-up time.)

Measuring method:

1. Measure the initial temperature of the water before the water is added to the vessel. (Example: The initial temperature T1 = 11°C)

2. Add the 1 litre water to the vessel.

3. Place the load on the centre of the shelf.

4. Operate the microwave oven at HIGH until the temperature of the water rises by a value ∆ T of (10 ± 2) K.

5. Stir the water to equalize temperature throughout the vessel.

6. Measure the final water temperature. (Example: The final temperature T2 = 21°C)

7. Calculate the microwave power output P in watts from above formula.

TEST PROCEDURES

HIGH VOLTAGE RECTIFIER

PROCEDURE

LETTER COMPONENT TEST

Room temperature ................................................................................................. T0 = 21°C

Initial temperature .................................................................................................. T1 = 11°C

Temperature after (28 + 3) = 31 sec [for R-22AM]................................................. T2 = 21°C

Temperature after (23 + 3) = 26 sec [for R-23AM/23AT] ....................................... T2 = 21°C

Temperature difference Cold-Warm......................................................................∆T1 = 10˚C

Measured output power

The equation is “P = 150 x ∆T” [for R-22AM] .......................... P = 150 x 10°C = 1500 Watts

The equation is “P = 180 x ∆T” [for R-23AM/23AT] ................ P = 180 x 10°C = 1800 Watts

JUDGMENT: The measured output power should be within the range of ± 15 % of the rated output

power.

CAUTION: 1°C CORRESPONDS TO 150 WATTS [R-22AM]/ 180 WATTS [R-23AM, R-23AT]. REPEAT

MEASUREMENT IF THE POWER IS INSUFFICIENT.

1000g

R-22AM R-23AM R-23AT

1000g

T1˚C

Heat up for 31 sec. for R-22AM

Heat up for 26 sec. for R-23AM/ R-23AT

B HIGH VOLTAGE TRANSFORMER TEST

WARNING: High voltage and large currents are present at the secondary winding and

filament winding of the high voltage transformer. It is very dangerous to work near this part when the oven is on. NEVER make any voltage measurements of the high-voltage circuits, including the magnetron filament.

CARRY OUT 3D CHECKS. Disconnect the leads to the primary winding of the high voltage transformer. Disconnect the filament and secondary winding connections from the rest of the HV circuitry. Using an ohmmeter, set on a low range, it is possible to check the continuity of all three windings. The following readings should be obtained:-

a. Primary winding approximately 1.8 Ω approximately 1.2 Ω b. Secondary winding approximately 75 Ω approximately 75 Ω c. Filament winding less than 1 Ω

1000g

T2˚C

R-22AM R-23AM, R-23AT

If the readings obtained are not stated as above, then the high voltage transformer is probably faulty and should be replaced. CARRY OUT 4R CHECKS.

C HIGH VOLTAGE RECTIFIER ASSEMBLY TEST

CARRY OUT 3D CHECKS. Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier can be tested

using an ohmmeter set to its highest range. Connect the ohmmeter across the terminal B+C of the high voltage rectifier and note the reading obtained. Reverse the meter leads and note this second reading. The normal resistance is infinite in one direction and more than 100 kΩ in the other direction. CARRY OUT 4R CHECKS.

NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE BATTERIES OF

THE MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT LEAST 6 VOLTS, BECAUSE OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.

R-22AM R-23AM R-23AT

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

D HIGH VOLTAGE CAPACITOR TEST

CARRY OUT 3D CHECKS. A. Isolate the high voltage capacitor from the circuit.

B. Continuity check must be carried out with measuring instrument which is set to the highest

resistance range.

C. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10MΩ

after it has been charged.

D. A short-circuited capacitor shows continuity all the time. E. An open capacitor constantly shows a resistance about 10 MΩ because of its internal 10MΩ

resistance.

F. When the internal wire is opened in the high voltage capacitor shows an infinite resistance. G. The resistance across all the terminals and the chassis must be infinite when the capacitor is

normal.

If incorrect reading are obtained, the high voltage capacitor must be replaced. CARRY OUT 4R CHECKS.

E SWITCH TEST

CARRY OUT 3D CHECKS. Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the following table.

Table: Terminal Connection of Switch

Plunger Operation COM to NO COM to NC

Released Open circuit Short circuit Depressed Short circuit Open circuit

If incorrect readings are obtained, make the necessary switch adjustment or replace the switch. CARRY OUT 4R CHECKS.

F FUSE F3, F4 M8A TEST

CARRY OUT 3D CHECKS.

If the fuses F3 and/or F4 M8A are blown, there could be shorts in the high voltage transformers T1 and/ or T2 or there is a ground in wire harness. Check and/ or replace the high voltage transformers T1 and/ or T2 or repair the wire harness.

CARRY OUT 4R CHECKS.

CAUTION: Only replace

G WEAK POINT F1 TEST

CARRY OUT 3D CHECKS.

COM; Common terminal, NO; Normally open terminal NC; Normally close terminal

fuses F3, F4 M8A with the correct value replacement.

If the weak point F1 is blown, there could be a shorts or grounds in electrical parts or wire harness. Check them and replace the defective parts or repair the wire harness.

CARRY OUT 4R CHECKS.

CAUTION: Only replace weak point F1 with the correct value replacement.

H FUSE F2 F6.3A TEST

CARRY OUT 3D CHECKS. If the fuse F2 F6.3A is blown when the door is opened, check the 1st. latch switch SW1, monitor switch

SW4 and monitor resistor R1. If the fuse F2 F6.3A is blown by incorrect door switching replace the defective switch(s) and the fuse F2 F6.3A.

CARRY OUT 4R CHECKS. CAUTION: Only replace fuse F2 F6.3A with the correct value replacement.

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

I TEMPERATURE FUSE TEST

1. CARRY OUT 3D CHECKS.

2. A continuity check across the temperature fuse terminals should indicate a closed circuit unless the temperature of the temperature fuse reaches specfied temperature as shown below.

Open Close Display or temperature temperature Condition Check point

Magnetron temperature fuse

Blower motor temperature fuse

Oven temperature fuse

TF4

TF1

TF2

TF3

150˚C

120˚C

Non resetable type

EE1

EE3

EE2 Oven shut

off Oven shut

off

3. CARRY OUT 4R CHECKS.

CAUTION: IF THE temperature fuse INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,

REPLACE temperature fuse.

R-22AM R-23AM R-23AT

Magnetron Test magnetron

Magnetron MG1, MG2 Failure: Test magnetron MG1, MG2. Check blower fan motor and ventilation opening.

Magnetron MG2 Failure: Test magnetron

Check blower fan motor and ventilation opening or rocked rotating of blower fan motor.

Food has been burned in oven. Temperature of oven inside is very high.

MG1 Failure:

MG1 and Blower fan motor.

MG2 and Blower fan motor.

J MONITOR RESISTOR R1 TEST

CARRY OUT 3D CHECKS. Disconnect the leads from the monitor resistor R1. Using an ohmmeter and set on a low range. Check

between the terminals of the monitor resistor R1.

The resistance of monitor resistor R1 should be read approx. 4.3Ω. If incorrect readings are obtained, replace the monitor resistor R1. CARRY OUT 4R CHECKS.

K THERMISTOR TEST

1. CARRY OUT 3D CHECKS.

2. Follow the procedures below for each thermistor. 2-1. MAGNETRON THERMISTOR TEST

Disconnect the connector of the magnetron thermistor from the switch harness. Measure the resistance of the magnetron thermistor with an ohmmeter. Connect the ohmmeter leads to the leads of the thermistor.

Room Temp. 59˚F (15˚C) 68˚F (20˚C) 77˚F (25˚C)

Resistance Approx. 373 kΩ Approx. 292 kΩ Approx. 231 kΩ If the meter does not indicate above resistance, replace the thermistor. 2-2. OVEN THERMISTOR (1) TEST

Disconnect the connector of the oven thermistor (1) from the switch harness. Measure the resistance of the oven thermistor (1) with an ohmmeter. Connect the ohmmeter leads to the leads of the thermistor.

Room Temp. 59˚F (15˚C) 68˚F (20˚C) 77˚F (25˚C)

Resistance Approx. 373 kΩ Approx. 292 kΩ Approx. 231 kΩ If the meter does not indicate above resistance, replace the thermistor. 2-3. OVEN THERMISTOR (2) TEST

Disconnect the two connectors of the magnetron thermistor and oven thermistor (2) from the switch harness. Measure the resistance of the oven thermistor (2) with an ohmmeter. Connect the ohmmeter leads to the leads of the thermistor.

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