Panasonic NN-A872SBBPQ User manual

Order Number: MOP02090053S2
Microwave Oven
NN-A872SBBPQ
32l Enamel
Stainless Steel
United Kingdom
Please fileand use thismanual together with the service manual for
Model Nos. NN-A850CB, Order Number MOP0090015C2
SPECIFICATIONS
1995 Matsushita ElectricIndustrial Co., Ltd. All rights reserved.
Unauthorized copying and distribution isaviolation of law.
1

1. PARTS LIST
Whenordering parts quote the complete part number. Donot quote the description of the part
without the part number.
Components identifiedbythe symbol have special safetycharacteristics, onlyreplace these
parts withparts suppliedbythe original manufacturer.
Forparts not showninthis simplifiedservice-manual, refertothe service-manual parts list for
the model NN-A850CBBPQ
Ref. No. PartNo. PartName& Description Qty
Remarks
75 E110D4V30SBP OUTER PANEL 1
2. DOOR ASSEMBLY
2

Ref. No. PartNo. PartName& Description Qty Remarks
D1 E302A4V30SBP DOOR ASCREEN B FACIAASSEMBLY 1
3. ESCUTCHEON BASE ASSEMBLY
3

Ref. No. PartNo. PartName& Description Qty Remarks
E1 E80724V30SBP DOOR OPENING BUTTON 1
E2 AEE80378A1AG DOOR OPENING BUTTON SPRING 1
E3 E800S4V30SBP ESCUTCHEON BASE ASSEMBLY 1
4. PACKING AND ACCESSORIES
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Ref. No. PartNo. PartName& Description Qty Remarks
P3 E06435870SP WIRERACK FOOT 1
P4 E060V5870SP WIRERACK 1
P5 E01089000GP TRAYPACKING 1
P11 E00034V30BT COOKBOOK/OPERATING INSTRUCTIONS 1
5

Order Number MOP00090015C2
Microwave Oven
NN-A880WB / NN-A850WB / NN-A850CB
SPECIFICATIONS
1995 Matsushita ElectricIndustrial Co., Ltd. All rights reserved.
Unauthorized copying and distribution isaviolation of law.
1

1. Inverter Warning
The inverterboardlooks like a regularPCB, however, this PCB drives the magnetron tube using
veryhigh voltages and current.
It has
1. Veryhigh voltage and high current
2. AnAluminium heat sink that becomes veryhot
3. The capacitors on the inverter circuitwill containahigh voltage
charge even when the oven isnot operating.
Donot
1. Donot touch the circuitryas itcontains veryhigh voltages. When
replacing the board please take extreme care to avoidpossible
electricshock. High voltages mayremaininthe circuit.
2. Donot touch the aluminium heat sink as itwill become veryhot. It
also contains high voltages.
3. Donot attempt to repairthe inverter PCB as thiscan be very
dangerous. Replace the high voltage inverter circuitas acomplete
unit. Return the oldunitfullyrepacked inthe original shipping
box and completed paper work.
4. Donot adjust or tamper with the preset volume on the inverter
board. Itisverydangerous to adjust thispreset without proper
test equipment.
5. Donot test the oven whilethe inverter grounding stripor screws
are loose. Itisverydangerous to operate the inverter circuitboard
without aproper ground connection.
Figure 1
2

InverterGounding
Figure 2
InverterPCB layout
2. Feature Chart
3

Function NN-A880WB NN-
A850WB NN
-A850CB
Microwave 6 6
Grill 3 3
Convection 17 17
Combination YES YES
Sensorreheat 2 -
Sensorcook 2 -
Sensorcombination 4 -
Weight defrost 3 3
Weight combination 8 12
Weight reheat - 2
Weight cook - 2
Stage cooking 3 3
Delay/Stand YES YES
More/Less YES NO
Kg-> lb/oz YES YES
Clock 12H 12H
Wordprompt English English
Function NN-A880WB NN-
A850WB NN
-A850CB
StepbyStep LED LED
3. Control Panel
4

4. Operation And Digital Programmer Circuit Test
Procdure
5

6

7

5. Schematic Diagram
8

6. Wiring Diagram
7. Description of Operating instruction
7.1. Variablepower cooking control
The HIGH VOLTAGE INVERTER POWER SUPPLY controls the output powerbya signal fromthe
digital Programmercircuit DPC. The powerrelay(RY1) turns on tosupplypowertothe inverter
circuit. The level of output poweris controlledbythe drive signal level fromthe invertercircuit.
NOTE1: The ON/OFF time ratiodoes not correspond withthe percentage of microwave power
since approximately2 seconds are requiredforheating the magnetron filament. / NOTE: 2 If
microwave cooking is over8 minutes on HIGH power, the fanmotorrotates for1 minute after
cooking tocool the ovenand electrical components.
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Dutycycles formicrowave cooking
Output DutyON/OFF
ON time 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
The digital programmercircuit controls the grill powerbyoperating the powerrelayRY4 inthe
sequence showninthe table below
Dutycycles forGrill Cooking
DutyON/OFF
ON Time OFF Time
Grill 1 66” 0”
Grill 2 54” 12”
Grill 3 42” 24”
7.3. Auto weight defrost, Auto weight Cook
Whenanautocontrol feature is selectedand the start padpressed:
1. The digital programmer circuitdetermines the power level and the
cooking time and indicates the operating state inthe display. The
tableshowsthe corresponding cooking times for each category
and its respective weight.
2. When the cooking time inthe displaywindow has elapsed, the
oven turns off automaticallyviathe control signal from the digital
programmer circuit.
Note: After auto cooking ifthe oven temperature isover the
predetermined temperature the fan motor rotates to cool the oven
and its components.
AutoWeight Defrost NN-A880WB NN-A850WB NN-A880CB
Category 1st Touch
Weight Cooking Time
Bread 100 45s
Meat Items 200 3m40s
Meat Joints 400 6m20s
Autoweight Cook NN-A880WB
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Category 1st Touch
Weight Cooking Time
9.Whole Chicken 1000 18m20s
10.ChickenPortions 300 9m30s
11.Beef/Lamb 500 14m40s
12.Casserole 800 56m40s
13.ChilledCrispyTop 300 10m
14.FrozenCrispyTop 300 14m
15.Bake Pastry 600 15m
16.Bake Cake 400 11m40s
Autoweight Cook NN-A850WB NN-A850CB
Category 1st Touch
Weight Cooking Time
1.ChilledMeal 300 3m30s
2. FrozenMeal 300 6m20s
3. FreshVegatables 100 2m20s
4. Fish 100 1m
5. Jacket Potatoes 200 16m30s
6.FrozenPotato
Products 200 10m
7. Whole Chicken 1000 18m20s
8. ChickenPortions 300 9m30s
9. Beef/Lamb 500 14m40s
10. Casserole 800 56m40s
11. ChilledCrispy
Top 300 10m
12. FrozenCrispy
Top 300 14m
13. ChilledPizza 200 7m40s
14. FrozenPizza 200 10m
15. Bake Pastry 600 15m
16. FruitCrumble 500 18m20s
7.4. Convection Cooking
1. The digital programmer circuitoperates the power relaysRY3,RY5
and RY6 inthe sequence as showninthe figure below.
2. When the oven reaches apredetermined temperature the digital
programmer circuitstops supplying power to relayRY5, resulting
inthe convection heater turning off.
3. When the temperature drops below the predetermined
temperature, the digital programmer circuitsupplies power to
11

power relayRY5 resulting inthe convection heater turning on.
Note: After the convection process, ifthe oven temperature is
higher than the predetermined temperature, the fan motor rotates
to cool the electroniccomponents and the oven.
Figure 1
Convection Cooking DutyCycles
7.5. Combination Cooking
Combination cooking is achievedbyoperating the microwave and heatermodes together
during one cooking cycle. There are three combination modes.
1. Combination (convection and microwave)
2. Combination (grill and microwave)
3. Combination (grill, convection and microwave)
The digital programmercircuit operators the powerrelays as showninthe figures below.
Whenthe oventemperature reaches the predeterminedtemperature, the digital programmer
circuit stops supplying powertorelay(RY5) resulting inthe convection heaterturning off.
During this time the digital programmercircuit continues tooperate relay(RY1) sothat
microwave activitycontinues at the dutycycle selected. The invertercontrol signal level is also
maintained. The microwave activitycontinues tocycle until the entire cooking programis
completed.
Whenthe oventemperature drops belowthe selectedtemperature, the digital programmer
circuit operates powerrelay(RY5) switching on the heaterelements.
Inthe case of grill combination the sequence applies withthe digital programmercircuit
switching powerrelay(RY4) tocontrol, the grill elements.
Withconvection, grill and micropowercombination. The grill elements and convection
elements are operatedalternativelywhilst the oventemperature is above the selectedlevel.
Convection And Microwave Combination DutyCycles
12

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
Figure 1
13

Convection and microwave dutycycles
Figure 2
Grill and microwave dutycycles
14

Grill,Convection and microwave dutycycles
7.6. One touch Auto sensor cooking NN-A880WB
Autosensorcook is a revolutionarywaytocook bymicrowave without setting a powerlevel or
selecting a time. All that is necessaryis toselect anautosensorprogrambefore starting to
cook. /
Understanding Autosensorcooking / / As food cooks, a certainamount of steamis produced.
If the food is covered, this steambuilds up and eventuallyescapes fromthe container. Inauto
sensorcooking, a carefullydesignedinstrument, calledthe humiditysensorelement, senses
the escape of steam. then, basedupon the autosensorprogramselected, the unit will
automaticallydetermine the correct powerlevel and the properlengthof time it will take tocook
the food.
NOTE: Autosensorcooking is successful withthe foods and recipes found inthe autosensor
cooking guide. Because of the vast differences infood composition, items not mentionedinthe
cooking guide shouldbe preparedinthe microwave ovenusing the powerselect and time
features. Please consult variable powermicrowave cook book forprocedures.
/ Explanation of the autosensorcooking process /
1. The shaded columns infigure 1indicate when the humidity
sensor heater ison.
2. During the 30 second period there isno microwave activity. When
calculating the T2 time byusing the formulabelow, make sure this
30 seconds issubtracted from the T0 time.
3. T1 time T0 time -30 seconds
4. T2 time when the steam escapes from the cooking container
placed inthe oven, the humiditysensor detects itand the
microprocessor calculates the balance of cooking time. ThisT2
15