Panasonic NN-A883WB User manual

MOP0307006C2
MicrowaveOven
NN-A813AB/ NN-A873SB/ NN-A883WB
32 Litre
EPG Europe
SPECIFICATIONS
1995 Matsushita ElectricIndustrial Co., Ltd. All rights reserved.
Unauthorizedcopying and distribution isaviolation oflaw.

1. Inverter Warning
The inverterboardlooks like a regularPCB, however, this PCB drives the magnetron tube using
veryhigh voltages and current.
Ithas
1. Veryhigh voltageand high current
2. AnAluminium heat sinkthat becomes veryhot
3. Thecapacitorson theinvertercircuitwill containahigh voltage
chargeevenwhentheovenisnotoperating.
Donot
1. Donottouchthecircuitryas itcontainsveryhigh voltages. When
replacing theboard please take extremecaretoavoidpossible
electricshock. High voltages mayremaininthecircuit.
2. Donottouchthealuminium heat sinkas itwill becomeveryhot. It
alsocontainshigh voltages.
3. DonotattempttorepairtheinverterPCB as thiscanbevery
dangerous. Replace thehigh voltageinvertercircuitas a
complete unit. Return theoldunitfullyrepackedintheoriginal
shipping boxand completedpaperwork.
4. Donotadjust or tamperwiththepreset volumeon theinverter
board. Itisverydangeroustoadjust thispreset withoutproper
test equipment.
5. Donottest theovenwhiletheinvertergrounding stripor screws
areloose. Itisverydangeroustooperate theinvertercircuitboard
withoutaproperground connection.
Figure 1

InverterGounding
Figure 2
InverterPCB layout
2. Feature Chart
Function A813ABEPG
Microwave 6
Grill 3
Convection 17
Combination YES
Sensorreheat 2
Sensorcook 2
Sensorcombination 4
Weight defrost 3
Weight combination 8
Weight reheat -
Weight cook -
Stage cooking 3
Delay/Stand YES
More/Less YES
Kg->lb/oz YES
Clock 12H
Wordprompt English
StepbyStep LED

3. Control Panel
4. Operation And Digital Programmer CircuitTest
Procdure

5. SchematicDiagram

6. Wiring Diagram
7. Description ofOperation
7.1. Variablecooking powercontrol
The HIGH VOLTAGEINVERTER POWER SUPPLYcontrols the output powerbya signal from
the Digital ProgrammerCircuit(DPC). The PowerRelay(RY1)turns on to supplypowerto the
invertercircuit. The level of output poweris controlledbythe drive signal level from the inverter
circuitas indicatedinthe table below.
/ NOTE1:The ON/OFF time ratiodoes not correspond with the percentage of microwave power
since approximately2 seconds are requiredforheating the magnetron filament.
NOTE2:Ifmicrowave cooking is over8 minutes on HIGH power, the fanmotorrotates for1

minute aftercooking to cool the ovenand its electrical components. /
DutyCycles forMicrowave Cooking
OUTPUT
(watts) DUTYON/OFF (seconds)
ON time OFF time
HIGH 1000 22 0
DEFROST 270 16 6
MEDIUM 600 22 0
LOW 440 22 0
SIMMER 250 15 7
WARM 100 8 14
7.2. Grill Cooking
The Digital ProgrammerCircuitcontrols the grill powerbyoperating the powerrelayRY4 inthe
sequence displayedinthe table below:
/
DutyCycles forGrill Cooking
DUTYON/OFF (seconds)
ON time OFF time
Grill 1 66 0
Grill 2 54 12
Grill 3 42 24
7.3. AutoWeightDefrost and AutoWeightCook
Whenanauto control feature is selectedand the startpadpressed:
1. TheDigital ProgrammerCircuitdetermines thepowerlevel and
thecooking timeand indicates theoperating state inthedisplay.
Thetablebelowshowsthecorresponding cooking times for each
categoryand its respectiveweight.
2. Whenthecooking timeinthedisplaywindowhas elapsed, the
oventurnsoff automaticallyviathecontrol signal from theDigital
ProgrammerCircuit.
Note: Afterauto cooking, ifthe oventemperature is overthe predeterminedtemperature then
the fanmotorwill thenrotate to cool the ovenand its components.
Auto Weight Defrost
CATEGORY 1stTOUCH
WEIGHT
(grams)
COOKINGTIME
Bread& Rolls 100 4m18s
MeatItems 200 3m40s
MeatJoints 400 6m20s

Auto Weight Cook
CATEGORY 1stTOUCH
WEIGHT
(Grams)
COOKINGTIME
ChilledPizza 400 08m20s
FrozenPizza 400 08m40s
ChilledQuiche 400 12m40s
FrozenQuiche 400 12m40s
ChickenPieces 500 14m40s
ChickenWhole 1300 23m55s
Pork / Veal 1200 35m00s
Beef 900 26m00s
Lamb 1200 30m05s
Tarte 6 -8 (pieces) 29m00s
7.4. Convection Cooking
1. TheDigital ProgrammerCircuitoperates thepowerrelaysRY3,
RY5and RY6inthesequence illustratedbelow.
2. Whentheovenreaches apredeterminedtemperaturethedigital
programmercircuitstopssupplying powertotherelayRY5,
resulting intheconvection heaterturning off.
3. Whenthetemperaturedropsbelowthepredetermined
temperature, thedigital programmercircuitsupplies powertothe
relayRY5resulting intheconvection heaterturning on.
Note:Aftertheconvection process, iftheoventemperatureis
higherthanthepredeterminedtemperature, thefanmotor rotates
tocool theelectroniccomponents and thoven.

Convection Cooking DutyCycles
7.5. Combination Cooking
Combination Cooking is achievedbyoperating the Microwave and Heatermodes together
during one cooking cycle. There are three possible combination modes:
1. Convection and Microwave
2. Grill and Microwave
3. Convection, Grill and Microwave
The Digital ProgrammerCircuitoperates the powerrelays as showninthe figures below. / /
Whenthe oventemperature reaches the predeterminedtemperature, the Digtal Progammer
Circuitstops supplying powerto the relayRY5 resulting inthe convection heaterturning off.
During this time, the Digital ProgrammerCircuitcontinues to operate relay(RY1)sothat
microwave activitycontinues atthe dutycycle selected. The Invertercontrol signal level is also
maintained. The microwave activitycontinues to cycle until the entire cooking programis
completed. / / Whenthe oventemperature drops belowthe selectedtemperature, the Digital
ProgrammerCircuitoperates powerrelayRY5, switching on the heaterelements. / / Inthe case
of grill combination, the sequence applies with the Digital ProgrammerCircuitswitching power
relayRY4 to control the grill elements. / / With convection, grill and micropowercombination,
the grill and covection elements are operatedalternativelywhilstthe oventemperature is above
the selectedlevel. / /
Covection and Microwave Combination DutyCycles
CONVECTION HEATER MICROPOWER
100 ~250 C Output
(W) On
(seconds) Off (seconds)
Medium 600 66 0
Low 440 66 0
Simmer 440 45 21
Warm 440 24 42

/
Grill and Microwave Combination DutyCycles
GRILL HEATER MICROPOWER
On Off Output
(W) On (seconds) Off (seconds)
Grill 1 66 0 Medium 600 66 0
Grill 2 48 18 Low 440 66 0
Grill 3 36 30 Simmer 440 45 21
Warm 440 24 42
/
Grill, Convection and Microwave Combination DutyCycles
CONVECTION
HEATER GRILL HEATER MICROPOWER
100 -250 C On Off Output
(W) On
(seconds)
Off
(seconds)
Grill
166 0 Medium
600 66 0
Grill
248 18 Low 440 66 0
Grill
336 30 Simmer
440 45 21
Warm 440 24 42
Convection and Microwave DutyCycles

Grill and Microwave DutyCycles
Grill, Convection and Microwave DutyCycles
7.6. OneTouchAutoSensor Cooking
Auto SensorCook is a revolutionarywayto cook byMicrowave without setting a powerlevel or
selecting a time. Itis onlynecessaryis to selectanauto sensorprogrambefore starting to cook.
Understanding Auto SensorCooking
As food cooks, a certainamount of steamis produced. ifthe food is covered, this steambuilds
up and eventuallyescapes from the container. InAuto Sensorcooking, a carefullydesigned
instrument calledthe HumiditySensorElement senses the escape escape of steam. Based
upon the Auto SensorProgramselected, the unitwill automaticallydetermine the correctpower

leveland calculate the lengh of time itwill take to cook the food.
NOTE:Auto SensorCooking is is successful with the foods and recipes found inthe Auto
SensorCooking guide. Because of the vastdifferences infood composition, items not
mentionedinthe cooking guide shouldbe preparedusing the powerselectand time features.
Please consultvariable powermicrowave cook book forproceedures.
Explanation of the Auto SensorCooking process:
1. TheshadedcolumnsinFigure1indicate whenthehumidity
sensor heaterison.
2. During the30 secondsperiod thereisno microwaveactivity.
Whencalculating theT2timebyusing theformulabelow, make
surethe30 secondsissubtractedfrom theT0time.
3. T1timeT0time-30 seconds.
4. T2timewhenthesteamescapes from thecooking container
placedintheoven,
8. Cautions toBeObserved When Troubleshooting
Unlike manyotherappliances, the microwave ovenis a high voltage, high current is device.
Though itis free from dangerinordinaryuse, extreme care shouldbe takenduring repair.
Caution
Servicemenshouldremovetheirwatches wheneverworking close
toor replacing themagnetron.
8.1. Check thegrounding
Donot operate on a twowire extension cord. The microwave ovenis designedto be usedwhen
grounded. Itis imperative, therefore, to ensure the appliance is properlygroundedbefore
beginning repairwork.
8.2. InverterWarnings
DANGER, HIGH VOLTAGEAND HIGH TEMPERATURE(HOT/LINE)OF THEINVERTER POWER
SUPPLY(U)
Thishigh voltageinverterpowersupplyhandles veryhigh voltage
and veryhigh currentfor themagnetron tube. Though itisfree from
dangerinordinaryuse, extremecareshouldbetakenduring repair.
Asyou cansee, itlooks like aTV flyback transformer, however, the
currentisextremelylargeand istherefore, dangerousduetothis
high currentand high voltage.
Thealuminium heat sinkisalsoenergizedwithhigh voltage(HOT),
sodo nottouchwhentheACinputterminal isconnected. The
powerdevices (Collector)isdirectlyconnectedtothealuminium
heat sink.

Thealuminium heat sinkmaybe(HOT)duetoheat energy,
therefore, extremecareshouldbetakenduring servicing.
Figure 1
HVInverterwarning
WARNINGFOR INVERTER POWER SUPPLY(U)GROUNDING
Check thehigh voltageinverterpowersupplycircuitgrounding.
Thishigh voltageinverterpowersupplycircuitboard must havea
properchassisground, theinvertergrounding bracket must be
connectedtothechassis. Iftheinverterboard isnotgroundedit
will expose veryhigh voltages and cause extremeDANGER!Be
surethat theinvertercircuitisproperlygroundedviatheinverter
earthbracket. Figure 2
InverterGrounding
WARNING!DISCHARGETHEHIGH VOLTAGECAPACITORS
For about30 secondsaftertheovenisturnedoff, anelectric
chargeremainsinthehigh voltagecapacitorsintheinverterpower
supplycircuitboard.
Whenreplacing or checking parts, removethepowerplug from the
outlet and shorttheinverteroutputterminal ofthemagnetron
filamentterminalstothechassisground withaninsulatedhandle

screwdrivertodischarge. Please besuretotouchthechassis
ground sidefirst and thenshorttotheoutputterminals.
Figure 3
Discharging the high voltage capacitors
WARNING
Thereishigh voltagepresentwithhigh currentcapabilities inthe
circuits oftheprimaryand secondarywindings, choke coil and
heat sinkoftheinverter. Itisextremelydangeroustoworkon or
nearthese circuits withtheovenenergized. DO NOTmeasurethe
voltageinthehigh voltagecircuitincluding thefilamentvoltageof
themagnetron.
WARNING
Nevertouchanycircuitwiring withyour hand nor withaninsulated
tool during operation.
8.3. Whenparts must bereplaced, removethepowerplug from the
outlet.
8.4. Whenthe10Afuse isblownduetotheoperation oftheshort
switch:
WARNING
Whenthe10A250V fuse isblownduetotheoperation oftheshort
switch, theprimarylatchswitchand shortswitchmust bereplaced.
Itisalsoimportanttochangethepowerrelay1(RY1) whenthe
continuitytest showsshortedcontacts.
1. Thismandatory. Referto“adjustments and measurements”for

thelocation ofthese switches.
2. Whenreplacing thefuse, confirm that ithas theappropriate rating
for these models.
3. Whenreplacing faultyswitches, besurethemounting tabsare
notbent, brokenor deficientintheirabilitytoholdtheswitches.
8.5. Avoidinserting nails, wireetc. through anyholes intheunit
during operation.
Neverinserta wire, nail oranyothermetal objectthrough the lamp holes on the cavityorany
holes orgaps, because suchobjects maywork as anantenna and cause microwave leakage.
8.6. Confirm afterrepair
1. Afterrepairor replacementofparts, make surethat thescrewsof
theoven, etc. areneitherloose nor missing. Microwaves might
leak ifscrewsarenotproperlytightened.
2. Make surethat all electrical connectionsaretightbeforeinserting
theplug intothewall outlet.
3. Check for microwaveenergyleakage. (Refertoprocedurefor
measuring microwaveenergyleakage).
CAUTION MICROWAVE RADIATION
DO NOTBECOME EXPOSEDTO RADIATIONFROMTHE
MICROWAVE GENERATOROROTHERPARTS CONDUCTING
MICROWAVE ENERGY
IMPORTANTNOTICE
Thefollowing components havepotentialsabove250V whileis
appliance isoperated.
-Magnetron
-High voltagetransformer(Locatedon inverter(U))
-High voltagediodes (Locatedon inverter(U))
-High voltagecapacitors(Locatedon inverter(U))
Payspecial attention inthese areas.
Whentheappliance isoperatedwiththedoor hinges or magnetron
fixedincorrectly, themicrowaveleakagecanreachmorethan5mW/
cm3. Afterrepairor exchange, itisveryimportanttocheck ifthe
magnetron and thedoor hinges arecorrectlyfixed.
8.7. Sharp Edges

Caution
Please use caution whenunpacking, installing or moving theunit,
as someexposededges maybesharp totouchand cause injuryif
nothandledwithcare.
9. PartsReplacementProcedure
9.1. Magnetron
1. Dischargethehigh voltagecapacitorson theinvertercircuit.
2. Removethefivescrewsshowninfigure1
3. Disconnect thetwohigh voltageleadsfrom themagnetron
4. Removethefour screwsholding themagnetron as shownin
figure2
NOTE:Afterreplacing the magnetron, tightenthe mounting screws making sure thatthere is no
gapbetweenthe waveguide and the magnetron to prevent microwave leakage.
Caution
Whenreplacing themagnetron, ensurethat theantennagasket is
inplace.
Note
Themagnetron usedfor thismodel isuniquefor theinverterpower
supplysystem. Make suretouse themagnetron as listedinthe
parts list. Figure 1
Removal of the magnetron
Figure 2

Screws to remove the magnetron
9.2. Inverterpowersupply(U)
1. Dischargethehigh voltagecapacitors
2. Unplug theH.V. Leadwires from themagnetron
3. Removetheconnector CN701 and CN702 from theinverterPCB
4. Removethetwoscrewsholding theinverterbase tothechassis
(See figure3)
5. Removetheonescrewholding theinverterearthwiretotheoven
chassis.
6. CarefullyremovetheinverterPCB and supportbase from the
oven.
7. RemovetheairguideE byun-clipping thecatchhooks
8. Removethefour screwsholding thePCB totheinvertersupport
base.
Caution whenreplacing the inverterpowersupply(U)
1. Make surethat grounding plate isinplace
2. Securelytightenthegrounding screwthrough thesideofthe
chassis(Base).
3. Securelyconnect the3leadwireconnectors
4. Make surethat theheat sinkhas enough space (gap)from the
oven. Take carenottotouchanyleadwiretothealuminium heat

sinkbecause itishot.
Figure 3
Removal of the inverterPCB
Figure 4
Disconnecting the PCB lock connector
9.3. Digital ProgrammerCircuit(DPC) and membranekeyboard.
NOTE:Ground anystatic electric builtup on yourbodybefore handling the DPC.
1. Disconnect all connectorsfrom theDPC.
2. Removethefour screwsholding theescutcheon base and slide
theescutcheon base upward slightly. removal iseasierwiththe
door open.
3. Release theflat cable.
4. Removethesixscrewsholding theDPCDU assembly
5. Removethedoor lever
6. Removetheninescrewsholding theDPCAUassembly
Toremove escutcheon pad
1. Removetheescutcheon bracket from theescutcheon base by
freeing the4catchhooks on theescutcheon base.