Sharp R-898(W) User manual

SHARP, SERVICE MANUAL
S00455R898EHW
SUPPLEMENT
MICROWAVE OVEN
WITH TOP AND
BOTTOM GRILLS
R-898(W)
R-898(AL)
In interests of user-safety the oven should be restored to its original condition
and only parts identical to those specified should be used.
This service manual covers only those items that differ from the R-875/R-885 S70225R875EHW
For further information on items not covered by this supplement refer to the Service Manual.
TABLE OF CONTENTS
PART CODE _DESCRIPTION
GCABUW468URTO Outer wrap (white)
GCABUWO045URP0 Outer wrap (aluminium)
:
mn
WW
DPWBFC431WRKZ CPU unit
GMADIC245URFO Display window mould
HPNLCW246URRO Control panel (printed) (white)
HPNLCA246URRO Control panel (printed) (aluminium)
JBTN-A295URRO Express pizza button
JBTN-A290URTO Auto cook button
JBTN-A300URTO Stop/Watt button
JBTN-A285URTO More/Less button
JKNBKA245URTO Vari knob
JKNBKA240URTO Timer knob OW HWW WOWWWW
aaa A OONNODND
ee ee ee ee ee ee ee
CDORFWO040URKO Door assy (white)
CDORFAO95URKO Door assy (aluminium)
GWAKPW390URFO Door frame (white)
GWAKPA390URTO Door frame (aluminium)
PGLSPW070URRO Door glass (white)
PGLSPAO070URRO Door glass (aluminium)
JHNDPA235URTO Door handle (aluminium)
JHNDPW240URFO Door handle base (white)
JHNDPA240URTO Door handle base (aluminium)
XCTSD40P25000 Screw 4mm x 25mm
XEBSD30P06000 Screw 3mm x 6mm
FWAKPW061URKO Door frame assy (white)
FWAKPA053URKO Door frame assy (aluminium)
MAAAAAAAAaAgRADT
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en es Oe be ee en ee Cee Crees Caen Sees Crees Cer
QOw-
TINS-A409URRO Quick start guide
TINS-A398URRO Operation manual
SHARP CORPORATION

CONTROL PANEL
ND at
eI
Digital dispiay and indicators:
1
ONO WwW
oOo
10
BOTTOM GRILL indicator
TOP GRILL indicator
CLOCK SET indicator
LESS/MORE indicator
INFORMATION indicator
TIMER indicator
COOKING IN PROGRESS indicator
WEIGHT (kg) indicator
MICROWAVE indicator
CONVECTION indicator
Operating buttons:
11
12
13
14
15
16
17
18
20
21
22
23
24
LANGUAGE button
LESS/MORE buttons
PIZZA button
EXPRESS PIZZA button
AUTO DEFROST button
AUTO COOK button
FUN MENUS button
COOKING MODE dial
Rotate the dial so that indicator points to
appropriate symbol:
for microwave cooking
for microwave cooking with TOP GRILL
for microwave cooking with BOTTOM GRILL
for microwave cooking with CONVECTION
for CONVECTION
for TOP GRILL
for BOTTOM GRILL
KX] for TOP & BOTTOM GRILLS
CONVECTION (°C) button
Press to change the convection setting.
MICROWAVE POWER LEVEL button
TIME/WEIGHT dial
Rotate the dial to enter either the
cooking/defrosting time or weight of food.
+1min/START @ button
INFO/CLOCK button
STOP button
RRR M GEE
R-898- 2

CONTROL PANEL PARTS
DOOR PARTS
R-898 - 3

SHAR-07379
SHARP SERVICE MANUAL
$70225R875EHW
MICROWAVE OVEN WITH
GRILL AND CONVECTION
MODELS R-875(B)
R-875(K)
R-875(W)
R-885(AL)
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 ........cccccccccscsssssessseessnneeeeeeceeeeeeeeeeseeeeeeeeeeseeeeeeeeeeeeeeeeeeuseeeeeeseeeseneees 2
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FUNCTION OF IMPORTANT COMPONENTS. .......cccccccccccccsscceeeseeseesssseeeeeseeseesseeesteesseeesteeesereeersananeeeta 13
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COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ..............cc0ccesesceessereevencessssssreenees 28
MICROWAVE MEASUREMENT ..........ccccccccesseesseeceecccecccsaeeeueeeessuaeuuceesssesnuuueeeseususseeaneesssesssnsasanennenereness 34
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PRINTED WIRING OF KEY AND JOG UNIT o0u.o.oc cece cece cceecccecccccececcececceceeusasueseseueseressceseneprapestenenenrpesaes 41
CPU UNIT CIRCUITDIAGRAM (0... ccccecce cece ccccescsceceeceseeseueausuaseeseeessseseereesseessueesseeeessrserssesssnaseaseneeesa 42
PRINTED WIRING BOARDOF POWER UNIT DIAGRAM .......cceeccceccccccccccccececceeeeccceeceueesuvevecesensensnesenans 43
PRINTED WIRING OF BOARD OF JOG SWITCH UNIT DIAGRAM uu... cece eeceeecccecccsseseesaeerneneceunes 44
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EXPLODED DIAGRAM OF OVEN PARTS. uu... .ccccccccccccccccseessececeeecsceseeeesseessssueeaussseeeseeeeveversensereenesaees 48
CONTOL PANEL & DOOR PARTS DIAGRAM .....c...ccccccccccescccsccceueenccecsecureeveneeecucessunsueeusereeesseanaesannneees 49
MISCELLANEOUS/PACKING & ACCESSORIES .....ccccccccccccccccccceccucessssseeseesscceeseceseseesureneerseeseneneaeees 50
SHARP CORPORATION

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 far inte utsattas for mikrovagsenergi som kan ustrala fran magnetronen eller
andre mikrovagsalstrande anordningar om dessa 4r felanslutna eller anvands pa fel satt.
Alla in-och utgangsanslutningar for mikrovagor, vagledare, flansar och packningar maste
vara fast anslutna.
Mikrovagsgeneratorn far inte arbeta utan att absorberande belastning ar ansluten. Titta
aldrig in i én 6ppen vagledare eller antenn nar mikrovagsgeneratorn ar pakopplad eller
laddad.
VAROITUS
MIKROAALTOSATELYA
Kayttaja ei saa joutua alttiiksi mikroaaltoenergialle, jota voi sateilla magnetronista tai
muusta mikroaaltoja kehittavasta laitteesta, jos sita kaytetaan tai jos se kytketaan vaarin.
Kaikkien mikroaaltoliitantéjen seka syétt6-etta ulostulopuolella, aaltoputkien laippojen ja
tiivisteiden tulee olla varmistettuja.
Mikroaaltouunnia ei koskaan saa kayttaa ilman kuormaa jossa mikroaaltoenergiaa kuluu.
Avoimeen aaltoputkeen tai antenniin ei koskaan saa katsoa virran ollessa kytkettyna.
ADVARSEL
MIKROBOLGESTRALING
Personell ma ikke utsettes for mikrobelge-energi som kan utstales fra magnetronen eller
andre mikrobolge-generende deler dersom apparatet feilbetjenes eller blir feiltikoplet.
Alle inn-og ut-tilkoplinger i forbindelse med mikrobelge-stralingen, balgeledere, flenser og
tetningsringer/pakninger ma festes ordentlig.
Aldri bruk apparatet med mindre en mikrobalge-absorberende last er plassert i
ovnsrommet.
Aldri se direkte inn i en apen belgeleder eller antenne imens apparatet er stromfgrende.
ADVARSEL
MIKROBOLGEBESTRALING
Man
bar
ikke
udseette
sig
for
mikrobolgebestraling
fra
magnetronen
eller
andre
mikrobolgefrembringende
anordninger,
hvilket
kan
ske
hvis
apparatet
er
forkert
tilsluttet
eller
bruges
forkert.
Alle
mikrobolgeindgange
og-udgange,
balgeledere,
flanger
og
tztningsstrimler
ma
vere
forsvarligt
udfort.
Anvend aldrig ovnen uden en mikrobglgesabsorberende anordning. Se aldrig ind i en
aben balgeleder eller antenne, mens ovnen er i brug.
R-875/885 - 2

GRILL AND CONVECTION MICROWAVE OVEN
R-875(B)/ R-875(K)/ R-875(W)/R-885(AL)
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.
CAUTION
MICROWAVE RADIATION
DO NOT BECOME EXPOSED TO RADIATION FROM THE
MICROWAVE GENERATOR OR OTHER PARTS THAT CON-
DUCT MICROWAVE ENERGY.
Note: The parts marked "*" are used in voltage more
than 250V. (Parts List)
Anm: Delar market med "*" har en spanning
Overstigande 250V.
Huom: Huolto-ohjeeseen merkitty "tandella" osatjoissa
jannite on yli 250 V.
Bemerk: Deler som er merket "asterisk" er utsatt for
spenninger over 250V til jord.
Bemeerk: "Dele mzerketmed stjerne benyttes med hgjere
speending end 250 volt.
WARNINGWARNING
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 "A" on the parts list may cause undue
microwave exposure, by themselves, or when they are damaged,
loosened or removed.
SHARP CORPORATION
OSAKA, JAPAN
R-875/885 - 3

WARNING TO SERVICE PERSONNEL
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
harness.
REMEMBER TO CHECK 3D
1) Disconnect the supply.
2) Door opened, and wedged open.
8) Discharge high voltage capacitor.
WARNING: AGAINST THE CHARGE OF THE HIGH-
VOLTAGE CAPACITOR
The high-voltage capacitor remains charged about 60 sec-
onds after the oven has been switched off. Wait for 60
seconds and then short-circuit the connection of the high-
voltage capacitor (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 3D checks and
then disconnect the leads to the primary of the High voltage
transformer. 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 3D
checks and reconnect the leads to the primary of the High
voltage transformer.
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 ail 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 two (2) minutes.
When the two minutes 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.
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.
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 geisoleerde
| schroevedraaier kortsluit tegen het chassis.
Sharp beveelt ten sterkste aan dat, voor zover mogelijk,
defecten worden opgespoord wanneer de stekker uit het
stopcontactis 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
geisoleerd 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
verbinat 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
nogmaais 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-875/885 - 4

t
Los hornos de microondas contienen circuitos eléctricos capaces de producir voltajes de alta tension y descargas
eléctricas. Para evitar el riesgo de electrocucion, absténgase de tocar los siguientes componentes: condensador de alta
tensién, transformador de alta tension, magnetrén, dispositivo del rectificador de alta tension y arnés de aita tensién.
RECUERDE LA COMPROBACION 3D RECUERDE LA COMPROBACION 4C
1) Desconecte la alimentaci6n.
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 conexidn del
condensador de alto voltaje (esto es, del conductor de
| conexidn del rectificador de alto voltaje) al chasis con un
| destornillador de mango aislado.
Se recomienda encarecidamente que siempre que sea
posible la localizacién de fallos se realice con la alimentaci6én
desconectada. Puede ser que en algunos casos sea
necesario conectar la alimentacién después de haber retirado
la carcasa exterior. En este caso, realice las comprobaciones
3D y luego desconecte los conductores del primario del
transformador de alimentacién. Asegurese de que estos
conductores permanezcan aislados de otros componentes y
del chasis del horno. (Use cinta aislante si es necesario).
Cuando termine la prueba efectie las comprobaciones 3D y
reconecte los conductores al primario del transformador de
alimentacion.
1) Conecte todos los componentes desconectados de los
componentes durante la prueba.
2) Coloque la carcasa exterior (cabina).
3) Conecte la alimentacién.
4) Compruebe todas sus funciones despues de poner en
marcha el horno.
Los hornos de microondas no deben funcionar vacios. Para
comprobar la presencia de energia de microondas dentro de
una cavidad, coloque una taza de agua fria en el plato giratorio
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 fria, efectue las comprobaciones 3D y vuelvaa
examinar las conexiones de los componentes que han sido
probados.
Cuando haya terminado la intervencion en el equipo y el horno
haya sido ensamblado de nuevo completamente, debera
comprobar la potencia de salida de microondas y realizar una
prueba de fugas de microondas.
{SV} Mikrovagsugnar innehaller kretsar som producerar mycket héga spanningar och strommar.
Kontakt med féljande komponenter kan /eda till d6dsfall:
Hdgspanningskondensator, transformator, magnetron, hdgspannings likriktare, hOgspannings kablage.
del horno, cierre la puerta y ponga la potencia en HIGH (alta) |
KOM IHAG ATT KONTROLLERA 3 STEG KOM IHAG ATT KONTROLLERA 4 STEG
1) Koppla fran stromkallan. 1) Anslut alla ledningar som anvants vid testning
2) Oppna dérren pa glant. 2) Satt tillbaka ytterhdljet.
3) Ladda ur hégspanningskondensatorn. 3) Anslut str6mkallan pa nytt.
= 4) S€tt pa ugnen. Kontrollera alla funktioner.
VARNING FOR LADDNINGEN |
HOGSPANNINGSKONDENSATORN
Hégspanningskondensatorn ar laddad i 60 sekunder efter
det att ugnen stangts av. Vanta 60 sekunder och korislut
sedan kondensatoms anslutning (dvs anslutningen till
| hdégspanningslikriktaren) till chassiet med hjaip av enisolerad
| skruvmejsel.
Mikrovagsugnar far inte anvandas tomma. Kontrollera
mikrovagsstralningen i olika delar av ugnen genom att placera
en kopp med kallt vatten pa ugnens tallrik, stang dérren, stall
in HIGH och stallin 2 minuter pa timern. Nar tva minuter har gatt
(timem visar 0) kontrollerar du om vattnet ar varmt. Om vattnet
fortfarande ar kallt utfér Du 3 steg kontroller och kontrollerar
anslutningarna till varje enskild komponent pa nytt.
Sharp rekommenderar att felsékning sker med str6mmen
frankopplad. Ibland kan det var nédvandigt att koppla pa
stro6mmen efter det att héljet aviagsnats, utfér da 3 Steg
kontrolien och koppla sedan fran ledarna till transformatorns
primarsida. Se till att ledarna ar isolerade fran andra
komponenter och chassiet. (Anvand isoleringsband om det
behévs). Nar Du testat fardigt utfér Du 3 Steg kontrollen och
ansluter ledningarna till transformatorns primarsida igen.
Nar all service ar klar och ugnen ihopskruvad skall ugnens
uteffekt och eventuellt mikrovagslackage kontrolleras.
R-875/885 - 5

Cr
|
forni
a
microonde
contengono
un
circuito
elettrico
in
grado
di
generare
tensioni
e
correnti
estremamente
elevate.
L’eventuale
contatto
con i
seguenti
componenti
pud
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 {'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
ll 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 (cioé 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, pud 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 IMPORTANT! 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.
| forni a microonde non devono mai funzionare a vuoto. Per |
verificare la presenza di energia da microonde all'interno |
di una cavita, 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 |'acqua é
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, é necessario controllare la potenza delle
microonde emesse ed eseguire un test per verificare che
non vi sia alcuna dispersione.
R-875/885 - 6

ITEM DESCRIPTION
230 Volts / 50 Hertz / Single phase, 3 wire earthed
Power Consumption Microwave cooking 1.45 kW Approx.6.5A
Convection cooking 1.86 kW Approx. 8.1A
Top Grill mode... eee 1.25 kW Approx. 5.4A
Grill cooking | Bottom Grill mode................ 0.65kW Approx. 2.8A
Top and Bottom mode......... 1.85 kW Approx. 8.0A
Micro and Top Grill ............... 2.65kW = Approx. 11.7A
Micro and Bottom Grill.......... 2.05kW Approx. 9.1A
Dual cooking | Micro and Top and Bottom
mode(Auto cook only) .......... 3.40 kW = Approx. 15.0A
Micro and Convection........... 2.06 kW Approx. 9.2A
900 W nominal of RF microwave energy (measured by method of IEC 60705)
Operating fequency 2450 MHz
Power Output
Top Grill Grill heating element Power Output
Bottom heating element Power Output
Case Dimensions Width 520 mm
Width_353 mm
Turntable diameter
Control Complement
Depth 482 mm
Depth 357 mm
Height 309 mm (including foot)
Height 207 mm
Touch Control System
Clock (1:00 - 12:59 or 0:00 - 23:59) / Timer (0 - 99 minutes)
Microwave Power for Variable Cooking
Repetition Rate;
AIG Hitivestiseretinineaisiene Full power throughout the cooking time
MEDIUM HIGH ...0... eee approx. 70% of FULL Power
MEDIUM wiiccccctsscetecedeuisituersnaeetiens approx. 50% of FULL Power
MEDIUM LOW ....... eee eeeeeteeceeteees approx. 30% of FULL Power
LOW ai sec centinadeainiantacdaaesaals: approx. 10% of FULL Power
Convection temperature control range:
250°C, 230°C, 220°C, 200°C, 180°C, 160°C, 130°C, 100°C, 70°C and 40°C
LESS/ MORE buttons, LANGUAGE button, EXPRESS PIZZA button
PIZZA button, FUN MENUS button, AUTO DEFROST button,
AUTO COOK button, COOKING MODE dial, CONVECTION button
MICROWAVE POWER LEVEL button, TIME/WEIGHT dial
STOP button, INFO/CLOCK button, + 1min@/ START button
Approx. 19 kg
Net Weight
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
As part of our policy of continuous improvement, we reserve the right to
alter design and specifications without notice
R-875/885 - 7

OVEN
SOP ce GOs DE
oo
10.
11.
12.
13.
14.
15.
Control panel
Oven lamp
Grill heating element (top grill)
Waveguide cover
Oven cavity
Turntable motor shaft
Grill heating element (bottom
grill)
Door seals and sealing surfaces
Door opening handle
Ventilation openings
Power cord
Outer cabinet
Turntable tray
{
ri
Low
rack
I
eee
29
High
rack
u
Y
CONTROL
PANEL
@1-3
Digital
display
and
indicators:
:
1
BOTTOM
GRILL
indicator
He AY
2
TOPGRiLLindicator
20
ar,
e
avt-4
3
CLOCK
SEthdicator
1D
_
OOF
4
LESSIMOREndicator
10
9
8
765
5
INFORMATION
indicator
6
TIMERindicator
7
COOKING
IN
PROGRESS
indicator
DOUBLE
GRILL
<>
HOT
AIR
8
VEIGHT
(kg)
indicator
9 MICROWAVE indicator
10 CONVECTION indicator
Operating buttons:
11 LANGUAGE button
12 EXPRESS PIZZA button
13 PIZZA button
14 FUN MENUS button
15 AUTO DEFROST button
16 AUTO COOK button
17 COOKING MODE dial
Rotate the dial so that indicator points to
appropriate symbol:
(3) for microwave cooking
for microwave cooking with TOP GRILL
for microwave cooking with BOTTOM GRILL
fe 36] for microwave cooking with CONVECTION
(36-] for CONVECTION
for TOP GRILL
for BOTTOM GRILL
for TOP & BOTTOM GRILLS
18 CONVECTION (°C) button
Press to change the convection setting.
19 TIME/WEIGHT dial
Rotate the dial to enter either the
cooking/defrosting time or weight of food.
20 +1min/START <)> button
21 INFO/CLOCK button
22 STOP button
23 MICROWAVE POWER LEVEL button
24 LESS/MORE buttons
NOTE:
If
the
clock
has
been
set,
some
one-touch
cooking
features
such
as
"MINUTE
PLUS"
are
disabled
after
three
minutes when the oven is not used. These features are automatically enabled when the door is opened and closed
or the STOP/CLEAR key is pressed.
R-875/885 - 8

OFF CONDITION
Closing the door activates the monitored latch switch SW1 and
the stop switch SW2.
IMP NT:
When the oven door is closed, the contacts COM-NC of the
monitor switch must be open. When the microwave oven is
plugged in a wall outlet (230V / 50Hz), the line voltage is
supplied to the noise filter.
Figure O-1 on page 33
1. The control unit is not energized. The display shows nothing
(Fig. O-1 (a)).
2. Open the door. The contacts (COM-NC) of the monitored
latch switch are closed and the control unit is energized. Then
contacts of relays RY1 and RY5 are closed, and the oven
lamp will light and the display will show "SELECT LAN-
GUAGE" (Fig. O-1(b)).
3. Close the door. And press the STOP button. The contacts
(COM-NC) of the monitored latch switch are opened and the
contacts of relay RY1 are opened and the oven lamp will be
turned off. The display will show "0". (Fig. O-1(c)).
4. Select language as follows.
4-1. Choose desired language by pressing the LANGUAGE
button.
4-2. Start the setting by pressing the START button. The
oven display will snow selected language.
5. Set the clock as follows.
5-1. Choose the 12 hour clock or the 24 hour clock by
pressing the CLOCK setting button.
5-2. Set hours by rotating the TIME/WEIGHT dial.
5-3. Change from hours to minutes by pressing CLOCK
setting button.
5-4. Set minutes by rotating the TIME/WEIGHT dial.
5-5. Start the clock by pressing CLOCK setting button.
NOTE: Energy save mode
1. Ifthe oven has not been used for more than 3 minutes, the
contacts of the relay RY5 will be opened and the control unit
will be not energized. Open and close the door, the control
unit will resume.
2. Ifthe clock is set, this energy save mode does not work.
MICROWAVE COOKING CONDITION
HIGH COOKING
Rotate the COOKING MODE dial to the G1 micro setting. And
press the MICROWAVE POWER LEVEL button once. And enter
the cooking time by rotating the TIME/WEIGHT dial. And start the
oven by pressing START button.
Function sequence Figure O-2 on page 34
CONNECTED COMPONENTS RELAY
Oven lamp, Turntable motor RY1
High voltage transformer RY2
Fan motor RY6
1. The line voltage is supplied to the primary winding of the high
voltage transformer. 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 voitage (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 inthe magnetron
generates a wavelength of 12.24 cm. This energy is chan-
nelled 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 RY1 + RY2 + RY6 go back to their home position. The
circuits to the oven lamp, high voltage transformer, fan motor
and turntable motor are cut off.
5. When the oven door is opened during a cooking cycle, the
switches come to the following condition.
Switch Contact Condition
During Oven Door
Cooking Open(No cooking)
i ..,COM-NO Closed Opened
Monitored latch switch COM-NC Opened Closed
Stop switch COM-NO- Closed Opened
: . COM-NO- Closed Opened
Monitor Switer COM-NC Opened Closed
The circuit to the high voltage transformer is cut off when the
contacts of relay RY2, and the contacts (COM-NO) of the moni-
tored latch switch SW1 and monitor switch SW3 are made open.
The circuit to the fan motor is cut off when the relay RY6 is made
open. The circuit to the turntable motor is cut off when the
contacts (COM-NO) of the monitored latch switch SW1 are made
open. The relay RY2 and RY6 are made open when the door is
opened. The 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 remaining time.
6. MONITOR SWITCH CIRCUIT
The monitor switch SW3 is mechanically controlled by the
oven door, and monitors the operation of the monitored
latch switch SW1.
6-1. When the oven door is opened during or after the cycle of
a cooking program, the monitored latch switch SW1 and
stop switch SW2 must open their contacts (COM-NO) first.
And the contacts (COM-NC) of the monitored latch switch
SW1 are made closed. After that the contacts (COM-NC) of
the monitor switch SW3 can be closed and the contacts
(COM-NO) of monitor switch SW3 are made open.
6-2. When the oven door is closed, the contacts (COM-NC) of
the monitor switch SW3 must be opened and the contacts
(COM-NQ) of monitor switch SW3 must be closed. After
that the contacts (COM-NQ) of the monitored latch switch
SW1 and the stop switch SW2 are made closed. And the
contacts (COM-NC) of the monitored latch switch SW1 are
made open.
6-3. When the oven door is opened and the contacts (COM-NO)
of the monitored latch switch SW1 remain closed, the fuse
F2 F8Awill blow. Because the relay RY1 and monitor switch
SWS are closed and a short circuit is caused.
MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW COOKING
When the microwave oven is preset for variable cooking power,
the line voltage is supplied to the high voltage transformer
intermittently within a 32-second time base through the relay
contact which is coupled with the current-limiting relay RY2. The
following levels of microwave power are given.
R-875/885 - 9

32 sec. ON
soowO (HGH) i 1 100%
een 24 sec. ON 8 sec. OFF
prow (MED ET | Aprox. 70%
18 sec. ON 14 sec. OFF
450W (MEDIUM) Approx. 50%
12 sec. ON 20 sec. OFF
270W
(MEUM
|
Approx.
30%
Q LOW,
6 sec. ON 26 sec. OFF
sown Low Approx. 10%
Note: The On/Offtime ratio does not exactly correspond to the
percentage of microwave power, because approx. 3
seconds are needed for heating up the magnetron
filament.
GRILL COOKING CONDITION
TOP GRILL (Figure O-3a)
In this condition the food is cooked by the top grill heating
element . Rotate the COOKING MODE dial to TOP GRILL
setting. And enter the desired cooking time by rotating the TIME/
WEIGHT dial. When the START button is pressed, the following
operations occur:
1. The numbers on the digital readout start the count down to
zero.
2. The oven lamp, cooling fan motor and turntable motor are
energized.
3. The relay RY3 is energized and the main supply voltage is
applied to the top grill heating element.
4. Now, the food is cooked by the top grill heating element.
BOTTOM GRILL (Figure O-3b)
In this condition the food is cooked by bottom grill heating
element energy. Rotate the COOKING MODE dial to 1 BOT-
TOM GRILL setting. And enter the desired cooking time by
rotating the TIME/WEIGHT dial. When the START button is
pressed, the following operations occur:
1. The numbers on the digital readout start the count down to
zero,
2. The oven lamp, cooling fan motor and turntable motor are
energized.
3. The relay RY4 is energized and the main supply voltage is
applied to the bottom grill heating element.
4. Now, the food is cooked by the bottom grill heating element.
TOP AND BOTTOM GRILLS (Figure O-3c)
In this condition the food is cooked by top and bottom grill heating
elements energy. Rotate the COOKING MODE dial to @ TOP
AND BOTTOM GRILLS setting. And enter the desired cooking
time by rotating the TIME/WEIGHT dial. When the START button
is pressed, the following operations occur:
1. The numbers on the digital readout start the count down to
zero.
2. The oven lamp, cooling fan motor and turntable motor are
energized.
3. The relay RY4 is energized and the main supply voltage is
applied to the bottom grill heating element.
4. The relay RY3 is energized and the main supply voltage is
applied to the top grill heating element.
5. Now, the food is cooked by the top and bottom grill heating
elements.
CONVECTION COOKING CONDITION
PRE-HEATING (Figure O-4)
Rotate the COOKING MODE dial to the convection setting.
And programme the desired convection temperature by touching
CONVECTION button. When the STARTbutton is touched, the
following operations occur:
1. Thecoilshut-offrelays RY1 and RY6 are energized, the oven
lamp, cooling fan motor and turntable motor are turned on.
2. The coil shut-off relays RY3 and RY4 are energized by
control unit and the main supply voltage is added to the top
and bottom heating elements.
3. When the oven temperature reaches the selected pre-heat
temperature, the following operations occur:
3-1. The coil shut-off relays RY3 and RY4 are energized by
control unit temperature circuit and thermistor, opening the
circuit to the top and bottom grill heating elements.
3-2. The oven will continue to function for 30 minutes, turning the
top and bottom heating elements on and off, as needed to
maintain the selected pre-heat temperature. The oven will
shut-down completely after 30 minutes.
CONVECTION COOKING (Figure O-4)
When the pre-heat temperature is reached, a beep signal will
sound indicating that the holding the temperature has been
reached in the oven cavity. Open the door and place the food to
cooked in the oven. Rotate the COOKING MODE dial to the
convection setting. And enter the cooking time by rotating the
TIME/WEIGHT dial. And select the desired cooking tempera-
ture by pressing the CONVECTION button. When the START
button is pressed, the following operations occur:
1. The numbers on the digital readout start the count down to
zero.
2. The oven lamp, cooling fan motor, turntable motor and
convection motor are energized.
NOTE: When the convection temperature 40°C is selected, the
convection motor is not energized.
3. The relays RY3 and RY4 are energized (if the cavity
temperature is lower than selected temperature) and the
main supply voltage is applied to the top and bottom heat-
ing elements to return to the selected cooking temperature.
4. Upon completion of the cooking time, the audible signal will
sound, and the oven lamp, turntable motor, cooling fan
motor, convection motor, top and bottom heating elements
are de-energized. At the end of convection cycle, if the cavity
air temperature rise above 120°C, the circuit to the relay RY6
will be maintained (by the thermistor circuit) to continue
operation of the cooling fan motor until temperature drops
below 105°C, at that time the relay RY6 will be de-energized,
turning off the fan motor.
DUAL COOKING CONDITION
MICROWAVE AND CONVECTION (Figure O-5a)
Rotate the COOKING MODE dial to s DUAL 1 setting. And
enter the desired cooking time by rotating the TIME/WEIGHT
dial. And press MICROWAVE POWER LEVEL button to set the
desired microwave power. And press the CONVECTION button
to set the cooking temperature. When the START button is
pressed, the following operations occur:
1. The numbers on the digital readout start the count down to
zero.
2. The oven lamp, cooling fan motor, turntable motor and
convection motor are energized.
3. The relay RY3 will be energized and the main supply voitage
is applied to the top grill heating element.
4. The relay RY4 is energized (if the cavity temperature is lower
than selected temperature) and the main supply voltage is
applied to the bottom heating element.
R-875/885 - 10

5. The relay RY2 is energized and the microwave energy is
generated by magnetron.
6. Now, the food is cooked by microwave and convection
energy simultaneously.
MICROWAVE AND TOP GRILL (Figure O-5b)
Rotate the COOKING MODE dial to && DUAL 2 setting. And
enter the desired cooking time by rotating the TIME/WEIGHT
dial. And press MICROWAVE POWER LEVEL button to set the
desired microwave power. When the START button is pressed,
the following operations occur:
1. The numbers on the digital readout start the count down to
zero.
2. The oven lamp, cooling fan motor and turntable motor are
energized.
3. The relay RY3 is energized and the main supply voltage is
applied to the top grill heating element.
4. The relay RY2 is energized and the microwave energy is
generated by magnetron.
5. Now, the food is cooked by microwave and top grill simulta-
neously.
MICROWAVE AND BOTTOM GRILL (Figure O-5c)
Rotate the COOKING MODE dial to DUAL 3 setting. And
enter the desired cooking time by rotating the TIME/WEIGHT
dial. And press MICROWAVE POWER LEVEL button to set the
desired microwave power. When the START button is pressed,
the following operations occur:
1. The numbers on the digital readout start the count down to
zero.
2. The oven lamp, cooling fan motor and turntable motor are
energized.
3. The relay RY4 is energized and the main supply voltage is
applied to the bottom grill heating element.
4. The relay RY2 is energized and the microwave energy is
generated by magnetron.
5. Now, the food is cooked by microwave and bottom grill
simultaneously.
AUTO POWER CONTROL OPERATION
ON/OFF TIME RATIO
In grill cooking, convection cooking or dual cooking, the top
heater, bottom heater or magnetron operate whithin a 54 second
time base. The following table is the ON / OFF time ratio at each
power output of the top heaters, bottom heater or magnetron.
80% 45 sec.
OFF TIME
0 sec.
5 sec,
9 sec.
14 sec.
18 sec.
29 sec. 25 sec.
24 sec. 30 sec.
36 sec.
41 sec.
45 sec.
30% 18 sec.
20% 13 sec.
AUTOMATIC COOKING
EXPRESS PIZZA
PIZZA
FUN MENUS
AUTO COOK
AUTO DEFROST
Above functions are automatic cooking. They automatically work
out the correct cooking mode and cooking time and/or cooking
temperature. They will cook according to the special cooking
sequence.
The magnetron, top or bottom heating elements, the fan motor or the convection motor will operate in accordance with
following specification.
1. OUTPUT POWER CONTROL (MANUAL COOK)
OPERATION MODE DEVICE
Microwave
SINGLE OPERATION
TOP GRILL (100%) Top heat
SINGLE OPERATION ep nedier
O74
BOTTOM GRILL (1100's) Bottom heater
Top heater
SINGLE OPERATION
TOP(100%/BOTTOM(100%)
DUAL OPERATION Bottom heater 100% 6min then 70% and 70% 9min then 50%
MICRO(100%)/TOP GRILL(100%) 100% 20min, then 70%
DUAL OPERATION Top heater 100% 15min, then 50%
MICRO(70 - 10%\/TOP GRILL(100%) |__ Microwave =
DUAL OPERATION Top heater 100% 15min, then 50%
MICROM00% BOTTOM GRILL(100%) 100% 20min, then 70%
DUAL OPERATION 100% T5min, then 50%
MICRO(70 - 10%)/BOTTOM GRILL(100%) |_ Microwave :
DUAL OPERATION Bottom heater 100% 15min, then 50%
100% 6min then 70% and 70% 9min then 50%
POWER CONTROL
100% 20min, then 70%
100% 15min, then 50%
100% 15min, then 50%
R-875/885 - 11

OPERATION MODE DEVICE POWER CONTROL
Microwave | In case same cooking mode is repeated within 1min 15sec (including stop, end), oven
Top heater | calculates total cooking time and reduce the power level.
Bottom heater
Repeat Cook
2. OUTPUT POWER CONTROL (AUTO COOK)
hk
Repeat Auto Cook
3. COOLING FAN OPERATION
The power level is not reduced 1 time cooking. But only in case same menu is repeated
within 1 min 15sec, the power level of micro and grillis reduced from 100% to 70% in 20mins
after starting of last cooking. (Even if the time of the last cooking is longer than 20mins, the
power level isn'treduced on the last cooking, and itis reduced from the beginning of the next
cooking.) However, in time calculated from the start of the 1st cooking, even if the Cook
mode changed, when repetition cooking of the menu with which 100% of top & bottom
heaters continues are performed, as shown in the following table, the power down of the
cooking of the 2nd henceforth is carried out. (The 1st cooking is not applied)
PREHEAT Cooling 60%
CONV. (OVEN) Cooling fan 60% 60 min. then 100%
Others Cooling fan
A cooling fan continues the rotation when Oven temperature is more than 120°C. Then,
it stops when it is less than 105°C
Indication NOW COOLING is indicated during the cooling fan movement after operation is finished.
(It isn't indicated during a fan movement to stop on the way.)
After cooking Cooling fan
4. CONVECTION POWER SETTING
PREHEATING
TEMP
HEATING 100%
100%
60%
250°C, 230°C, 220°C, 200°C, 180°C, 160°C, 130°C, 100°C, 70°C, 40°C
CONVECTION
7c | 40°C
*WITHOUT _ | HEATING 10% _| 10%
PREHEATING [ELEMENT BOTTOM 50% 30% | 20%
HEATING 10%
PR
EHEATING | ELEMENT| BOTTOM | 90% 70% | 60% | 60% | 50% | 50% | 40% | 30% | 20%
COOLING FAN 60% 60min, then 100%
CONV. FAN 100% 0%
DUAL CONVECTION
*WITH
NOTE
*WITHOUT
PREHEATING | ELEMENT
PREHEATING | ELEMENT
TEMP 250°C | 230°C | 220°C | 200°C | 180°C | 160°C
HEATING
30% | 20% | 10% | 10% | 10%
30% | 20%
100%
HEATING
COOLING FAN
CONV. FAN
*xThe oven temp was checked by the thermometer when each stage is started .
If the oven temp is same or higher than 105°C, the oven was judged as "with preheating".
When the oven temp is lower than 105°C or the cooling fan stops, the oven was judged as “without
preheating".
R-875/885 - 12

DOOR OPEN MECHANISM
The door can be opened by pulling the door handie. When the
handle is pulled, the latch head is pulled, the latch head is moved
upward, and released from the latch hook now the door can be
opened.
Latch hook
b
SW2: Stop switch
SW3: Monitor switch
SW1 [Monitored
Oo latch switch
Figure D-1. Door Open Mechanism
MONITORED LATCH SWITCH SW1
1. When the oven door is closed, the contacts (COM-NO) of the
switch must be closed. And the contacts (COM-NC) must be
opened.
2. When the oven door is opened, the contacts (COM-NO) of
the switch must be opened, and the contacts (COM-NC)
must be closed.
STOP SWITCH SW2
1. When the oven door is closed, the contacts (COM-NO) of the
switch must be closed.
2. When the oven door is opened, the contacts (COM-NO) of
switch must be opened.
MONITOR SWITCH SW3
The monitor switch is activated (the contacts opened) by the lower
latch head on the door while the door is closed. The switch is
intended to render the oven inoperative by means of blowing the
fuse F2 F8A when the contacts of the monitored latch switch SW1
fail to open when the door is opened.
Function
1. When the door is opened, the contacts (COM-NC) of monitor
switch SWS close. At this time the contacts (COM-NO) of
monitored latch switch SW1 are open.
2. Asthe door closed, the monitor switch SW3 contacts (COM-
NC) are opened and contacts (COM-NQ). The contacts
(COM-NOQ) of monitored latch switch SW1 and stop switch
SW2 are closed.(On opening the door, each of these switches
operate inversely.)
3. If the door is opened and the monitored latch switch SW1
contacts (COM-NO) fail to open, the fuse F2 (F8A) blows
immediately after closing of the monitor switch (COM-NC)
contacts.
CAUTION: BEFORE REPLACING A BLOWN FUSE F2 F8A,
TEST THE MONITORED LATCH SWITCH SW1
AND MONITOR SWITCH SW3 FOR PROPER
OPERATION. (REFER TO CHAPTER “TEST
PROCEDURE’).
FUSE F1 20A 250V
If the wire harness or electrical components are short-circuited,
this fuse Fi blows to prevent an electric shock of fire hazard.
FUSE F2 F8A 250V
1. if the wire harness or electrical components are short-
circuited, this fuse biows to prevent an electric shock or fire
hazard.
2. The fuse also blows when the monitored latch switch SW1
remains closed with the oven door open and when the
monitor switch SW3 contact (COM-NC) closes.
3. The fuse also blows when the asymmetric rectifier, H.V.
rectifier,.H.V. wire harness, H.V. capacitor, magnetron or
secondary winding of high voltage transformer is shorted.
TC TRANSFORMER
T/C transformer converts A.C. line voltage into low voltage to
drive the control unit.
THERMAL CUT-OUT TC1 125°C (MG)
This thermal cut-out protects the magnetron against overheat.
If the temperature goes up higher than 125°C because the fan
motor is interrupted or the ventilation openings are blocked, the
thermal cut-out TC1 will open and the oven will switch off. The
defective thermal cut-out must be replaced with a new one.
THERMAL CUT-OUT TC2 145°C (OVEN)
This thermal cut-out protects the oven against overheating or fire
inside the oven. If the temperature rises above 145°C the thermal
cut-out opens the oven will switch off. When the cut-out cools
down to the operating temperature of 115°C, the contacts of the
thermal cut-out will close again.
ASYMMETRIC RECTIFIER
The asymmetric rectifier is solid state device that prevents
current flow is both directions. And it prevents the temperature
rise of the high voltage transformer by blowing the fuse F2 F8A
when the high voltage rectifier is shorted.
ASYMMETRIC
RECTIFIER
HIGH VOLTAGE RECTIFIER
The rated peak reverse voltage of D1 of the asymmetric rectifier
is 6 KV. The rated peak reverse voltage of D2 of the asymmetric
rectifier is 1.7 KV. D1 and D2 of the asymmetric rectifier or high
voltage rectifier are shorted when the each peak reverse voltage
goes beyond the each rated peak reverse voltage. (The process
of the blowing the fuse F2 F8A.)
1. The high voltage rectifier is shorted by some fault when
microwave cooking or dual cooking.
2. The peak reverse voltage of D2 of the rectifier goes beyond
the rated peak reverse voltage 1.7 KV in the voltage doubler
circuit.
3. D2 of the rectifier is shorted.
4. The large electric currents flow through the high voltage
winding of the high voltage transformer.
5. The large electric currents beyond 8A flow through the
primary winding of the high voltage transformer.
6. The fuse F2 F8A blows by the large electric currents.
7. The power supplying to the high voltage transformer is cut off.
NOISE FILTER
The noise filter assembly prevents radio frequency interference
that might flow back in the power circuit.
TURNTABLE MOTOR TTM
The turntable motor rotates the turntable.
R-875/885 - 13

FAN MOTOR FM
The fan motor drives a blade which draws external cool air. This
cool air is directed through the air vanes surrounding the
magnetron and cools the magnetron. This air is channelled
through the oven cavity to remove steam and vapours given off
from heating food. Itis then exhausted through the exhausting air
vents of the oven cavity.
CONVECTION MOTOR CM
The convection motor drives the convection fan and provides the
heated air.
TOP GRILL HEATING ELEMENT GH1
The grill heating element is provided to brown the food and is
located on the top of the oven cavity.
BOTTOM GRILL HEATING ELEMENT GH2
The grill heating element is provided to brown the food and is
located at the base of the oven cavity.
CONVECTION COOKING SYSTEM
This oven is designed with a hot air heating system where food
is heated by forced circulation of the hot air produced by the grill
heating elements.
The air heated by the grill heating elements is circulated through
the convection passage provided on the outer casing of the oven
cavity by means of the convection fan which is driven by the
convection motor. It is then enters the inside of the oven through
the vent holes provided on the back side of the oven. Next, the
hot air heats the food on the turntable and leaves the oven cavity
through the vent in the oven cavity rear wall.
In this way, the hot air circulates inside the oven cavity to raise
its temperature and, at the same time, comes into contact with
the food being cooked.
When the temperature inside the oven cavity reaches the se-
lected temperature, the heating elements are de-energized.
When the temperature inside the oven cavity drops below the
selected temperature, the heating elements are energized again.
In this way, the inside of the oven cavity is maintained at
approximately the selected temperature.
When the convection time reaches “0”, the heating elements are
de-energized and the convection fan stops operating and the
oven shuts off. At that time if the cavity air temperature has rised
above120°C, the fan motor remains rotating. Automatically the
fan motor will be shut down at low temperature (less than 105°C).
ON
THERMISTOR
OFF
FIRE SENSING FEATURE
The oven will stop its operation when there is a fire in the oven
cavity in microwave cooking condition.
LSI measures the voltage across the temperature measurement
circuit intermittently within 32-seconds time base since the oven
is started in microwave cooking condition. The oven will stop its
operation when the difference of the voltage is more than 0.781
volts in microwave cooking condition.
1. Within a 32-seconds base, the thermistor is energized for 2
seconds. At that time, the voltage across the temperature
measurement circuit is measured.
2. The oven carries out the procedure above again. If the
second voltage is 0.781 V higher than first voltage, LSI judges
it as a fire in the oven cavity and stop the oven.
3. WhenLSl judges it as a fire in the oven cavity, LS! will switch
off the relays to high voltage transformer and fan motor and
LSI stops countring down.
Door Oven Cavity
Grill HeatingO
Element
ConvectionO
Passage
Cooling
Fan
‘“. Convectionl
Motor
. Convectionl
* Turntable Fan
Bottom Grill O
Heating Element
TurntableB
Motor
Insulation
Figure D-2. Convection Cooking Syste
OPEN JUDGE BY THERMISTOR
1. If the temperature of the thermistor does not rise to
more than 40°C after 4 minutes and 15 seconds from
when the oven is started in convection, grill (top and
bottom grills) or dual cooking mode, the oven is turned
off.
2. When the thermistor or the wire harness to the thermis-
tor is opened, the oven is turned off after 4 minutes and
15 seconds because this condition is same as above.
30: . 32 (sec.)
N I:
sensing ° | | '
VOLTAGE OFF
e,
y
Sensing the voltage across temperature measurement circuit.
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 (F8A) in the monitored latch switch - monitor switch
circuit, check the monitored latch switch and monitor switch before replacing the fuse F2 (F8A).
R-875/885 - 14

OOTING GUIDE
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POWER SUPPLY CORD
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H.V. HARNESS
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R-875/885 - 15

PROCEDURE
LETTER
A
COMPONENT TEST
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 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 (IEC 60705)
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 AT (°C) during this microwave heating period, the calorie of
the water is V x AT.
The formula is as follows:
P xt/4.187 = V x A T+ 0.55 x me (T2-T0)/4.187 =P (W) = 4.187 x Vx AT/t +0.55 x me (T2-TO)A
Our condition for water load is as follows:
Room temperature (TO) ... around 20°C Power supply Voltage.............. Rated voltage
Water load... eeeeeeereeeees 1000 g Initial temperature (T1) ......... eee 1021°C
Heating time ......... eee eeeeeeeeeeees 47 sec. Mass of container (MC) .......cceseeeeeeees 330 g
P = 90 x AT +0.55 x mc (T2-T0)/47
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.
. Select stirring devices and measuring instruments in order to minimize addition or removal of heat.
. 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 heat-
up 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 for the temperature of the water rises by a value A T of
10°C.
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.
Room temperature ..............cce To=21°C Initial temperature .......000.000.. T1=11°C
Temperature after (47 + 3) = 50 SOC. oo. cceccccccecsssesetessceseveussecstcseesssnetecevenanvarsas T2 = 21°C
Temperature difference Cold-Warm ........ccccccccccessescscssscssceresseesssscnsscestvsetasenerere AT1 = 10°C
Measured output power
The equation is “P = 90 X AT” ooo eeeceesceeesecsessetesssessceseeseesseeeee P = 90 x 10°C = 900 Watts
R-875/885 - 16

PROCEDURE
LETTER
COMPONENT TEST
JUDGMENT: The measured output power should be at least + 15 % of the rated output power.
CAUTION: 1°C CORRESPONDS TO 90 WATTS. REPEAT MEASUREMENT IF THE POWER |S
INSUFFICIENT.
Heat up for 50 sec
HIGH VOLTAGE TRANSFORMER TEST
WARNING: _ High voltage and large currents are present at the secondary winding and
filament winding of the high voltage transformer. itis 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 winding. The following readings should be
obtained:-
a. Primary Winding .................:cee approximately 1.9 Q
b. Secondary Winding ..........: cesses approximately 124 Q
C. Filament WINING... eeeeeeeesseeeeeaeeeeeeeenees less than 1 Q
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.
HIGH VOLTAGE RECTIFIER 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 kQ in the other direction.
CARRY OUT 4R CHECKS. A
B
ASYMMETRIC RECTIFIER TEST MEO 2
CARRY
OUT
3D
CHECKS.
C
¢/
RECTIFIER
isolate the high voltage rectifier assembly from the HV circuit. The asymmetric rectifier can be tested
using an ohmmeter set to its highest range across the terminals A+B of the asymmetric rectifier and
note the reading obtained. Reverse the meter leads and note this second reading. If an open circuitis
indicated in both directions then the asymmetric rectifier is good. If the asymmetric rectifier is shorted
in either direction, then the asymmetric rectifier is probably faulty and must be replaced with high voltage
rectifier. When the asymmetric rectifier is defective, check whether magnetron, high voltage rectifier,
high voltage wire or filament winding of the high voltage transformer is shorted.
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, BE-
CAUSE OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIREC-
TIONS.
R-875/885 - 17