Panasonic NN-A880WB User manual

OrderNumberMOP00090015C2
MicrowaveOven
NN-A880WB/ NN-A850WB/ NN-A850CB
SPECIFICATIONS
1995 Matsushita ElectricIndustrial Co., Ltd. All rights reserved.
Unauthorizedcopying and distribution isaviolation oflaw.
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1. InverterWarning
Theinverterboard looks like aregularPCB, however, thisPCB drives themagnetron tubeusing
veryhigh voltages and current.
Ithas
1. Veryhigh voltageand high current
2. AnAluminiumheat sinkthat becomes veryhot
3. Thecapacitorson theinvertercircuitwill containahigh voltage
chargeevenwhentheovenisnotoperating.
Donot
1. Donottouchthecircuitryas itcontainsveryhigh voltages. When
replacing theboardplease take extremecaretoavoidpossible
electricshock. High voltages mayremaininthecircuit.
2. Donottouchthealuminiumheat sinkas itwill becomeveryhot. It
alsocontainshigh voltages.
3. DonotattempttorepairtheinverterPCB as thiscanbevery
dangerous. Replace thehigh voltageinvertercircuitas acomplete
unit. Returntheoldunitfullyrepackedintheoriginal shipping box
and completedpaperwork.
4. Donotadjust ortamperwiththepreset volumeon theinverter
board. Itisverydangeroustoadjust thispreset withoutproper
test equipment.
5. Donottest theovenwhiletheinvertergrounding striporscrews
areloose. Itisverydangeroustooperate theinvertercircuitboard
withoutaproperground connection.
Figure1
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InverterGounding
Figure2
InverterPCB layout
2. FeatureChart
Function NN-A880WB NN-A850WB
NN-A850CB
Microwave 6 6
Grill 3 3
Convection 17 17
Combination YES YES
Sensor reheat 2 -
Sensor cook 2 -
Sensor combination 4 -
Weightdefrost 3 3
Weightcombination 8 12
Weightreheat - 2
Weightcook - 2
Stagecooking 3 3
Delay/Stand YES YES
More/Less YES NO
Kg->lb/oz YES YES
Clock 12H 12H
Word prompt English English
StepbyStep LED LED
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3. Control Panel
4. Operation And Digital ProgrammerCircuit Test
Procdure
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5

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5. SchematicDiagram
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6. Wiring Diagram
7. Description of Operating instruction
7.1. Variablepowercooking control
TheHIGHVOLTAGE INVERTERPOWERSUPPLYcontrolstheoutputpowerbyasignal from the
digital ProgrammercircuitDPC. Thepowerrelay (RY1)turnson tosupplypowertotheinverter
circuit. Thelevel ofoutputpoweriscontrolledbythedrive signal level from theinvertercircuit.
NOTE1:TheON/OFF timeratiodoes notcorrespond withthepercentageofmicrowave power
since approximately2secondsarerequiredfor heating themagnetron filament. / NOTE:2If
microwave cooking isover8minutes on HIGHpower, thefanmotor rotates for 1minuteafter
cooking tocool theovenand electrical components.
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Dutycycles for microwave cooking
Output DutyON/OFF
ONtime OFF time
High 1000W 22” 0”
Defrost 440W 16” 6”
Medium 600W 22” 0”
Low 440W 22” 0”
Simmer 440W 15” 7”
Warm 440W 8” 14”
7.2. Grill Cooking
Thedigital programmercircuitcontrolsthegrill powerbyoperating thepowerrelay RY4inthe
sequence showninthetablebelow
Dutycycles for Grill Cooking
DutyON/OFF
ONTime OFF Time
Grill 1 66” 0”
Grill 2 54” 12”
Grill 3 42” 24”
7.3. Autoweightdefrost, AutoweightCook
Whenanautocontrol featureisselectedand thestartpadpressed:
1. Thedigital programmercircuitdetermines thepowerlevel and the
cooking timeand indicates theoperating state inthedisplay. The
tableshowsthecorresponding cooking times foreachcategory
and its respectiveweight.
2. Whenthecooking timeinthedisplaywindow has elapsed, the
oventurnsoff automaticallyviathecontrol signal fromthedigital
programmercircuit.
Note:Afterautocooking iftheoventemperatureisoverthe
predeterminedtemperaturethefanmotorrotates tocool theoven
and its components.
AutoWeightDefrostNN-A880WBNN-A850WBNN-A880CB
Category 1stTouch
Weight Cooking Time
Bread 100 45s
MeatItems 200 3m 40s
MeatJoints 400 6m 20s
AutoweightCookNN-A880WB
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Category 1stTouch
Weight Cooking Time
9.WholeChicken 1000 18m 20s
10.ChickenPortions 300 9m 30s
11.Beef/Lamb 500 14m 40s
12.Casserole 800 56m 40s
13.ChilledCrispyTop 300 10m
14.FrozenCrispyTop 300 14m
15.Bake Pastry 600 15m
16.Bake Cake 400 11m 40s
AutoweightCookNN-A850WBNN-A850CB
Category 1stTouch
Weight Cooking Time
1.ChilledMeal 300 3m 30s
2. FrozenMeal 300 6m 20s
3. FreshVegatables 100 2m 20s
4. Fish 100 1m
5. JacketPotatoes 200 16m 30s
6.FrozenPotato
Products 200 10m
7. WholeChicken 1000 18m 20s
8. ChickenPortions 300 9m 30s
9. Beef/Lamb 500 14m 40s
10. Casserole 800 56m 40s
11. ChilledCrispy
Top 300 10m
12. FrozenCrispy
Top 300 14m
13. ChilledPizza 200 7m 40s
14. FrozenPizza 200 10m
15. Bake Pastry 600 15m
16. FruitCrumble 500 18m 20s
7.4. Convection Cooking
1. Thedigital programmercircuitoperates thepowerrelaysRY3,RY5
and RY6inthesequence as showninthefigurebelow.
2. Whentheovenreaches apredeterminedtemperaturethedigital
programmercircuitstopssupplying powertorelayRY5, resulting
intheconvection heaterturning off.
3. Whenthetemperaturedropsbelow thepredetermined
temperature, thedigital programmercircuitsupplies powerto
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powerrelayRY5resulting intheconvection heaterturning on.
Note:Aftertheconvection process, iftheoventemperatureis
higherthanthepredeterminedtemperature, thefanmotorrotates
tocool theelectroniccomponents and theoven.
Figure1
Convection Cooking DutyCycles
7.5. Combination Cooking
Combination cooking isachievedbyoperating themicrowave and heatermodes togetherduring
onecooking cycle. Therearethree combination modes.
1. Combination (convection and microwave)
2. Combination (grill and microwave)
3. Combination (grill, convection and microwave)
Thedigital programmercircuitoperatorsthepowerrelays as showninthefigures below.
Whentheoventemperaturereaches thepredeterminedtemperature, thedigital programmer
circuitstopssupplying powertorelay (RY5)resulting intheconvection heaterturning off. During
thistimethedigital programmercircuitcontinues tooperaterelay (RY1)sothatmicrowave
activitycontinues atthedutycycleselected. Theinvertercontrol signal level isalsomaintained.
Themicrowave activitycontinues tocycleuntil theentirecooking program iscompleted.
Whentheoventemperaturedropsbelowtheselectedtemperature, thedigital programmercircuit
operates powerrelay (RY5)switching on theheaterelements.
Inthecase ofgrill combination thesequence applies withthedigital programmercircuit
switching powerrelay (RY4)tocontrol, thegrill elements.
Withconvection, grill and micro powercombination. Thegrill elementsand convection elements
areoperatedalternativelywhilsttheoventemperatureisabove theselectedlevel.
Convection And Microwave Combination DutyCycles
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Convection Heater Micropower
100 -250 C OUTPUT ON OFF
Medium 600W 66 0
Low 440W 66 0
Simmer 440W 45 21
Warm 440W 24 42
Grill And Microwave Combination DutyCycles
Grill Heater Micropower
ON OFF OUTPUT ON OFF
Grill 1 66 0 Medium 600W 66 0
Grill 2 48 18 Low 440W 66 0
Grill 3 36 30 Simmer 440W 45 21
Warm 440W 24 42
Grill Convection And Microwave Combination DutyCycles
Convection
Heater Grill Heater Micropower
100 -250 C ON OFF OUTPUTON OFF
Grill
166 0 Medium 600W 66 0
Grill
248 18 Low 440W 66 0
Grill
336 30 Simmer 440W 45 21
Warm 440W 24 42
Figure1
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Convection and microwave dutycycles
Figure2
Grill and microwave dutycycles
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Grill,Convection and microwave dutycycles
7.6. OnetouchAutosensorcooking NN-A880WB
Autosensor cookisarevolutionaryway tocookbymicrowave withoutsetting apowerlevel or
selecting atime. All thatisnecessaryistoselectanautosensor program beforestarting tocook.
/
Understanding Autosensor cooking / / Asfood cooks, acertainamountofsteam isproduced. If
thefood iscovered, thissteam buildsup and eventuallyescapes from thecontainer. Inauto
sensor cooking, acarefullydesignedinstrument, calledthehumiditysensor element, senses the
escapeofsteam. then, basedupon theautosensor program selected, theunitwill automatically
determinethecorrectpowerlevel and theproperlengthoftimeitwill take tocookthefood.
NOTE:Autosensor cooking issuccessful withthefoodsand recipes found intheautosensor
cooking guide. Because ofthevastdifferences infood composition, itemsnotmentionedinthe
cooking guideshouldbepreparedinthemicrowave ovenusing thepowerselectand time
features. Please consultvariablepowermicrowave cookbookfor procedures.
/ Explanation oftheautosensor cooking process /
1. Theshadedcolumnsinfigure1indicate whenthehumiditysensor
heaterison.
2. During the30 second period thereisno microwaveactivity. When
calculating theT2timebyusing theformulabelow, make surethis
30 secondsissubtractedfromtheT0time.
3. T1timeT0time-30 seconds
4. T2timewhenthesteamescapes fromthecooking container
placedintheoven, thehumiditysensordetects itand the
microprocessorcalculates thebalance ofcooking time. ThisT2
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timeisthenshowninthedisplayand beginscounting down.
Balance ofcooking (T2time)
Thebalance ofcooking timewhichiscalledT2time, canbecalculatedbythefollowing formula.
/ T2time(insec.)=T1timexKfactor
NOTE:Remember, theT1timestartsafterthestartpadistapped. ThecoefficientKis
programmedintothemicroprocessor memoryand they arelistedinthefollowing tables along
withtheP1and P2power. /
NOTE:When“More“or “Less”padisselected, theKfactor varies resulting inT2timetobe
increasedor decreased.
Calculating theT2time
Example1:Ifthet1timeismeasuredtobe2minutes and 40 seconds, and theautosensor
program isselectedissensor reheat. Fish(Program 4)
T2=T1xK
=2min. and 40 sec. X. 0.3
=48 sec.
Catergory P1POWER P2POWER KFACTOR
STANDARD
1. Chilled
meal HIGH HIGH 1.6
2. Frozen
meal MED HIGH 0.9
Figure1
Autosensor cooking
8. Cautions toBeObserved When Troubleshooting
Unlike manyotherappliances, themicrowave ovenisahigh voltage, high currentisdevice.
Though itisfree from dangerinordinaryuse, extremecareshouldbetakenduring repair.
Caution
Servicemenshouldremovetheirwatches wheneverworking close
toorreplacing themagnetron.
8.1. Check thegrounding
Donotoperateon atwowireextension cord. Themicrowave ovenisdesignedtobeusedwhen
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grounded. Itisimperative, therefore, toensuretheappliance isproperlygroundedbefore
beginning repairwork.
8.2. InverterWarnings
DANGER, HIGHVOLTAGE AND HIGHTEMPERATURE (HOT/LINE)OFTHE INVERTERPOWER
SUPPLY(U)
Thishigh voltageinverterpowersupplyhandles veryhigh voltage
and veryhigh currentforthemagnetron tube. Though itisfree from
dangerinordinaryuse, extremecareshouldbetakenduring repair.
Asyou cansee, itlooks like aTVflyback transformer, however, the
currentisextremelylargeand istherefore, dangerousduetothis
high currentand high voltage.
Thealuminiumheat sinkisalsoenergizedwithhigh voltage(HOT),
sodo nottouchwhentheACinputterminal isconnected. The
powerdevices (Collector)isdirectlyconnectedtothealuminium
heat sink.
Thealuminiumheat sinkmaybe(HOT)duetoheat energy,
therefore, extremecareshouldbetakenduring servicing.
Figure1
HV Inverterwarning
WARNINGFORINVERTERPOWERSUPPLY(U) GROUNDING
Check thehigh voltageinverterpowersupplycircuitgrounding.
Thishigh voltageinverterpowersupplycircuitboardmust havea
properchassisground, theinvertergrounding bracket must be
connectedtothechassis. Iftheinverterboardisnotgroundeditwill
expose veryhigh voltages and cause extremeDANGER!Besure
that theinvertercircuitisproperlygroundedviatheinverterearth
bracket. Figure2
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InverterGrounding
WARNING!DISCHARGE THE HIGHVOLTAGE CAPACITORS
Forabout30 secondsaftertheovenisturnedoff, anelectriccharge
remainsinthehigh voltagecapacitorsintheinverterpowersupply
circuitboard.
Whenreplacing orchecking parts, removethepowerplug fromthe
outlet and shorttheinverteroutputterminal ofthemagnetron
filamentterminalstothechassisground withaninsulatedhandle
screwdrivertodischarge. Please besuretotouchthechassis
ground sidefirst and thenshorttotheoutputterminals.
Figure3
Discharging thehigh voltagecapacitors
WARNING
Thereishigh voltagepresentwithhigh currentcapabilities inthe
circuits oftheprimaryand secondarywindings, choke coil and heat
sinkoftheinverter. Itisextremelydangeroustoworkon ornear
these circuits withtheovenenergized. DO NOTmeasurethevoltage
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inthehigh voltagecircuitincluding thefilamentvoltageofthe
magnetron.
WARNING
Nevertouchanycircuitwiring withyourhand norwithaninsulated
tool during operation.
8.3. Whenparts must bereplaced, removethepowerplug fromthe
outlet.
8.4. Whenthe10Afuse isblownduetotheoperation oftheshort
switch:
WARNING
Whenthe10A250Vfuse isblownduetotheoperation oftheshort
switch, theprimarylatchswitchand shortswitchmust bereplaced.
Itisalsoimportanttochangethepowerrelay1(RY1) whenthe
continuitytest showsshortedcontacts.
1. Thismandatory. Referto“adjustments and measurements”forthe
location ofthese switches.
2. Whenreplacing thefuse, confirm that ithas theappropriate rating
forthese models.
3. Whenreplacing faultyswitches, besurethemounting tabsarenot
bent, brokenordeficientintheirabilitytoholdtheswitches.
8.5. Avoidinserting nails, wireetc. through anyholes intheunit
during operation.
Neverinsertawire, nail or anyothermetal objectthrough thelampholes on thecavityor any
holes or gaps, because suchobjectsmay workas anantennaand cause microwave leakage.
8.6. Confirm afterrepair
1. Afterrepairorreplacementofparts, make surethat thescrewsof
theoven, etc. areneitherloose normissing. Microwaves might
leak ifscrewsarenotproperlytightened.
2. Make surethat all electrical connectionsaretightbeforeinserting
theplug intothewall outlet.
3. Check formicrowaveenergyleakage. (Refertoprocedurefor
measuring microwaveenergyleakage).
CAUTIONMICROWAVE RADIATION
DO NOTBECOMEEXPOSEDTO RADIATIONFROMTHE
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MICROWAVE GENERATOROROTHERPARTSCONDUCTING
MICROWAVE ENERGY
IMPORTANTNOTICE
Thefollowing components havepotentialsabove250Vwhileis
appliance isoperated.
-Magnetron
-High voltagetransformer(Locatedon inverter(U))
-High voltagediodes (Locatedon inverter(U))
-High voltagecapacitors(Locatedon inverter(U))
Payspecial attention inthese areas.
Whentheappliance isoperatedwiththedoorhinges ormagnetron
fixedincorrectly, themicrowaveleakagecanreachmorethan5mW/
cm3. Afterrepairorexchange, itisveryimportanttocheck ifthe
magnetron and thedoorhinges arecorrectlyfixed.
8.7. SharpEdges
Caution
Please use caution whenunpacking, installing ormoving theunit,
as someexposededges maybesharptotouchand cause injuryif
nothandledwithcare.
9. PartsReplacement Procedure
9.1. Magnetron
1. Dischargethehigh voltagecapacitorson theinvertercircuit.
2. Removethefivescrewsshowninfigure1
3. Disconnect thetwohigh voltageleadsfromthemagnetron
4. Removethefourscrewsholding themagnetron as showninfigure
2
NOTE:Afterreplacing themagnetron, tightenthemounting screwsmaking surethatthereisno
gapbetweenthewaveguideand themagnetron topreventmicrowave leakage.
Caution
Whenreplacing themagnetron, ensurethat theantennagasket isin
place.
Note
Themagnetron usedforthismodel isuniquefortheinverterpower
supplysystem. Make suretouse themagnetron as listedinthe
parts list.
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Figure1
Removal ofthemagnetron
Figure2
Screwstoremove themagnetron
9.2. Inverterpowersupply(U)
1. Dischargethehigh voltagecapacitors
2. Unplug theH.V. Leadwires fromthemagnetron
3. RemovetheconnectorCN701 and CN702 fromtheinverterPCB
4. Removethetwoscrewsholding theinverterbase tothechassis
(See figure3)
5. Removetheonescrew holding theinverterearthwiretotheoven
chassis.
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