National NN-C781JF Service Manual
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National NN-C781JF Service Manual

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Service Manual
Specifications:
Specifications:
Power Source:
Power Requirement: Microwave
Output:
Microwave Frequency:
Timer:
Outside Dimensions:
Oven Cavity Dimensions:
Weight:
Models:
Heater
Microwave (ICE 705)
Heater
Output power: IEC705-88 Test Procedure
Specifications subject to change without notice.
®
240V AC Single Phase, 50Hz .......... For KNQ Models
230V-240V AC Single Phase, 50Hz . For MNQ, YNQ Models
220V AC Single Phase, 50Hz .......... For HNE, TNE, YKE, KKE, ZPE Models
220V AC Single Phase, 50/60Hz ..... For SNM Models
120V AC Single Phase, 60Hz .......... For WNT Models
1260W
1550W
1000W
1515W
2450MHz
30min (HIGH) / 99min. 59sec
400mm (W) x 520mm (D) x 312mm (H)
373mm (W) x 373mm (D) x 206mm (H)
15.5kg
ORDER NO. SIMMC 0110022C3
E1
Microwave Oven
NN-C781JF
NN-C781JF
© 2001 Shanghai Matsushita Microwave
Oven Co.,Ltd
All rights reserved. Unauthorized copying
and distribution is a violation of law.

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Summary of Contents for National NN-C781JF

  • Page 1 ORDER NO. SIMMC 0110022C3 Service Manual Microwave Oven NN-C781JF Specifications: Models: NN-C781JF Specifications: Power Source: 240V AC Single Phase, 50Hz ..For KNQ Models 230V-240V AC Single Phase, 50Hz . For MNQ, YNQ Models 220V AC Single Phase, 50Hz ..For HNE, TNE, YKE, KKE, ZPE Models 220V AC Single Phase, 50/60Hz ..

  • Page 2: Table Of Contents

    WARNING This service information is designed for experienced repair technicians only and is not designed for use by the general public. It does not contain warnings or cautions to advise non-technical individuals of potential dangers in attempting to service a product. Products powered by electricity should be serviced or repaired only by experienced professional technicians.
  • Page 3 DANGER OF HIGH VOLTAGE AND HIGH TEMPERATURE (HOT/LIVE) OF THE INVERTER POWER SUPPLY INVERTER WARNING This Inverter board looks like a regular PCB. However, this PCB drives the magnetron tube with extremely high voltage and high current. NEW H.V. IT HAS: 1. Very high voltage and high current circuits. It functions the same as the high voltage transformer and high voltage capacitor in ordinary microwave ovens.

  • Page 4: Feature Chart

    FEATURE CHART MODEL NN-C781JF FEATURE Three Stage Cooking Grill Convection Bake Combination Turbo Defrost Sensor Reheat One Touch Cook (weight) Sensor Cook Child Safety Lock Delay Start Timer/Stand Digital Clock CONTROL PANEL NN-C781JF Display Windows Micro Power Pad Sensor Reheat Pad Grill Pad Conv.Bake Pad...

  • Page 5: Operation And Digital Programmer Circuit Test Procedure

    OPERATION AND DIGITAL PROGRAMMER CIRCUIT TEST PROCEDURE CHINESE Power connected, then scroll display “ 88.88 ” . Press Start pad once for CHINESE + ENGLISH Chinese only. Press twice for both Chinese and English sisplay. Press 3 times for English only. Press 4 times for BAHASA only. ENGLISH BAHASA 1.
  • Page 6 5. Turbo Defrost 10. Demonstration Mode The domonstration mode designed for retail store display. It is not OPERATION SCROLL DISPLAY designed for home use. Cooking will not operate during 1. Set the weight for 1 kg by press- demonstration mode. ing 1.0 kg pads.

  • Page 7: Schematic Diagrams

    SCHEMATIC DIAGRAM NN-C781JF (EXCEPT ZPE & WNT) NOTE: Door closed. CAUTION Unit is not operating. NEW H.V. HIGH VOLTAGE AREA Ground THERMAL CUTOUT MAGNETRON (HEATER) Chassis 2M261-M32F PRIMARY LATCH SWITCH SECONDARY LATCH SWITCH SHORT SWOTCH GROUNDING CHASSIS GROUND FUSE FAN MOTOR...
  • Page 8 SCHEMATIC DIAGRAM NN-C781JF (ZPE, WNT) NOTE: Door closed. CAUTION Unit is not operating. NEW H.V. HIGH VOLTAGE AREA Ground THERMAL CUTOUT MAGNETRON (HEATER) Chassis 2M261-M32G PRIMARY LATCH SWITCH SECONDARY LATCH SWITCH SHORT SWOTCH GROUNDING CHASSIS GROUND FUSE FAN MOTOR INVERTER...

  • Page 9: Description Of Operating Sequence

    DESCRIPTION OF OPERATING SEQUENCE 1. Variable power cooking control Variable Power Cooking HIGH-VOLTAGE INVERTER POWER SUPPLY (U) controls output OUTPUT INVERTER POWER SETTING RY-1 POWER(%) CONTROL power by the signal from Digital Programmer Circuit (DPC). Power relay APPROX. SIGNAL 1 stays on but the inverter drive signal to control it’s output power. HIGH 100% stay ON...
  • Page 10 5. Combination Cooking Microwave (RY 1) Combination Combination cooking is accomplished by microwave and convection ON (SEC) OFF (SEC) cooking being done alternately during one combination cooking cycle. One combination cooking cycle is 22 seconds. (A) During combination cooking, the digital programmer circuit controls ON-OFF time of both power relay 1 and 4 as shown in Figure.

  • Page 11: Cautions To Be Observed When Troubleshooting

    CAUTIONS TO BE OBSERVED WHEN TROUBLESHOOTING Unlike many other appliances, the microwave oven is high-voltage, high WARNING current equipment. Though it is free from danger in ordinary use, extreme Never touch any circuit wiring with your hand nor with an care should be taken during repair.
  • Page 12 6.Confirm after repair (A) After repair or replacement of parts, make sure that the screws of the oven, etc. are neither loose nor missing. Microwaves might leak if screws are not properly tightened. (B) Make sure that all electrical connections are tight before inserting the plug into the wall outlet.

  • Page 13: Disassembly And Parts Replacement Procedure

    DISASSEMBLY AND PARTS REPLACEMENT PROCEDURE 1. Magnetron 1. Discharge the high voltage capacitors. 2. Remove A screw holding magnetron on bracket. 3. Remove 2 high voltage lead wires. 4. Remove circulation fan motor bracket and belt. (2 screws) 5. Remove air guide. (2 screws) 6.
  • Page 14 3. Inverter Power Supply (U) 1. Discharge high voltage capacitors. 2. Remove 2 screws holding magnetron bracket. (Remove grounding wire) 3. Remove 3 screws holding inverter and fan motor assembly. 4. Unplug 3 connectors of inverter PCB. 5. Remove 2 screws holding inverter PCB on to bracket. NOTE: Do not pull by lead wires but make sure to pull housing unless PCB or lead wire may break.
  • Page 15 4. Door assembly 1. Remove door spring right side. NOTE: Please hold door unless door become fall down. 2. Remove door arm lever by pushing tab and turn clock wise. 3. Remove door spring left. 4. Insert flat blade screw driver to release hinge pin from left hinge. PUSH 5.
  • Page 16 6. Heater 1. Remove belt. 2. Remove 2 lead wires from heater. BELT 3. Remove 2 screws holding heater and oven temperature sensor. TO RELEASE HEATER UNIT 4. Turn right to release hooks to remove heater assembly. 5. Remove a screw to release heater. 7.

  • Page 17: Component Test Procedure

    COMPONENT TEST PROCEDURE 5. Inverter Power Supply (U) CAUTION NEW. H.V. DO NOT try to REPAIR this H.V. Inverter power supply 1. High voltage is present at the high voltage terminal of (U).Replace as whole H.V. Inverter(U) Unit. the High Voltage Inverter (U) including aluminum heat sink during any cook cycle.
  • Page 18 6. Sensor Cooking AUTO SENSOR COOKING/REHEAT PROCESS Auto sensor cooking is a revolutionary way to cook by microwave without setting a power level or selecting a time. All that is necessary is to select an Auto Sensor Program before starting to cook.
  • Page 19 8. Steam Sensor and Digital Programmer Circuit In order to determine if the steam sensor function of the digital programmer circuit is in working order or not, do the following test. 1) Place a water load (150 cc) in the oven. 2) Tap Sensor Reheat pad.

  • Page 20: Measurements And Adjustments

    MEASUREMENTS AND ADJUSTMENTS WARNING * For continued protection against radiation hazard, replace only with identical replacement parts(For touch models Part ANE6142-1450,Type V-16G-3C26-M for Primary latch switch; Part No. A61425180AP, Type No. L-3C2-2 for Secondary latch switch; Part No. A61785180AP, Type No. L-2C2-2 for short switch and Part.

  • Page 21: Procedure For Measuring Microwave Energy Leakage

    PROCEDURE FOR MEASURING MICROWAVE ENERGY LEAKAGE WARNING WARNING Check for radiation leakage after every servicing. Should AVOID CONTACTING ANY HIGH VOLTAGE PARTS. the leakage be more than 2 mW/cm . After repairing or replacing any radiation safety device, keep a written record for future reference, the leakage reading must be recorded on the service repair ticket while in the customer’s home.

  • Page 22: Troubleshooting Guide

    TROUBLESHOOTING GUIDE DANGER HIGH VOLTAGES 1. DO NOT RE-ADJUST PRESET VOLUME on the H.V.Inverter (U). It is very dangerous to repair or adjust without sufficient test equipment because this circuit handles very large current with high voltage. Off alignment of inverter board operation will be dangerous.
  • Page 23 (Trouble 2) Other troubles SYMPTOM CAUSE CORRECTIONS Oven is dead. 1. Open or loose lead wire harness Check fan motor when thermal cutout is defec- Fuse is OK. 2. Open thermal cutout (Cavity) tive. No display and no operation at all. 3.
  • Page 24 (Trouble 3) Trouble related Digital programmer circuit SYMPTOM STEP CHECK RESULT CAUSE/CORRECTIONS No display when oven is first plugged in Fuse resistor R28 1Ω Normal STEP 2 Open Shorted circuit of IC-10 Q10 emitter Abnormal ➝ IC-1, CX320, DISPLAY (Output terminal) Normal = 5V Membrane switch continuity Abnormal...
  • Page 25 3. Check component by circuit tester. Make sure remove inverter PCB when continuity check Do not test component when inverter PCB is installed 1. How to check power transistors (Q701, Q702). To measure, suck FORWARD REVERSE a solder from its legs completely unless faulse reading may Some Ω...
  • Page 26 7. Apply extra solder onto Q701 and Q702 legs and Apply extra solder printed foil pattern to be able to hold main large current of more than 15A. Apply extra solder for large current flow For easy removal of solder, apply some solder first than suck it all. Base 8.
  • Page 27 HOW TO CHECK THE SEMICONDUCTORS USING AN OHM METER INVERTER BOARD PARTS LIST (A606Y4V00GP) Pcs/ Ref.No. Part No. Part name & Description Remarks C701 ECWF5104N300 CAPACITOR 0.1µF, 500VDC POLYESTER CAPACITOR C702 ECQE2405T847 4µF, 250VDC FILM CAPACITOR C703 ECWF5454N300 0.45µF, 500VDC FILM CAPACITOR C704,C705 ECWH30822JUA...

  • Page 28: Exploded View And Parts List

    EXPLODED VIEW AND PARTS LIST - 28 -...
  • Page 29 PARTS LIST NOTE 1: When ordering replacement part(s), please use part number(s) shown in this part list. Do not use description of the part. 2: Important safety notice: Components identified by mark have special characteristics important for safety. When replacing any of these components, use only manufacture’s specified parts. NOTE “A”...
  • Page 30 Pcs/ Ref.No. Part No. Part name & Description Remarks B62308250AP FUSE 18A, 125V (WNT) F63264760JP TURNTABLE MOTOR EXCEPT WNT F63264080AP TURNTABLE MOTOR F64504J00XN SENSOR COVER B F65434X80MN SENSOR COVER C F65854Y60XN INVERTER BRACKET F67634X80MN INVETTER BRACKET B F66624X80MN GROUNDING PLATE A62314000AP FUSE HOLDER EXCEPT ZPE &...
  • Page 31 DOOR ASSEMBLY Pcs/ Ref.No. Part No. Part name & Description Remarks DOOR E (U) F302K4J00XN RIGHT DOOR ARM F3044-1640 DOOR C F30854J00XN F3252-1450 DOOR ARM SPACER XTN3 + 7Q SCREW LEFT DOOR ARM F3054-1640 DOOR KEY SPRING B F3230-1600 DOOR A (U) F30015G00NXN WIRING MATERIAL MAGNETRON...
  • Page 32 ESCUTCHEON BASE ASSEMBLY Pcs/ Ref.No. Part No. Part name & Description Remarks F603L5G00HN D.P.CIRCUIT F603L5G00MN D.P.CIRCUIT F603L5G00YN D.P.CIRCUIT D.P.CIRCUIT F603L5G00TN YKE,TNE D.P.CIRCUIT F603L5G00WN F603L5G00SN D.P.CIRCUIT KKE,SNM F603L5G00KN D.P.CIRCUIT F603L5G00ZP D.P.CIRCUIT MEMBRANE SWITCH F630Y5G00NHN HNE,MNQ,YNQ,YKE,TNE MEMBRANE SWITCH F630Y5G00NWN F630Y5G00NKN MEMBRANE SWITCH KKE,KNQ,SNM F630Y5G00NZP MEMBRANE SWITCH...
  • Page 33 PACKING AND ACCESORIES Pcs/ Ref.No. Part No. Part name & Description Remarks F00035G00HN INSTRUCTION MAUNAL HNE,MNQ,YNQ,YKE,TNE F00035G00WN INSTRUCTION MAUNAL F00035G00KN INSTRUCTION MAUNAL KKE,KNQ,SNM F00035G00ZP INSTRUCTION MAUNAL F00324040XN EARTH CAUTION LABEL TNE,WNT F01025G00NHN PACKING CASE, PAPER HNE,MNQ,YNQ,YKE,TNE F01025G00NWN PACKING CASE, PAPER F01025G00NKK PACKING CASE, PAPER KKE,SNM...

  • Page 34: Schematic Diagram

    DIGITAL PROGRAMMER CIRCUIT SCHEMATIC DIAGRAM YN TN MN HN SN KN ZP WN JPR1 10K OPEN 3.3K SHORT 1.5K 6.2K JPR2 OPEN - 34 -...
  • Page 35 NN-C781JF P (1) STOP/RESET H (2) START AK (3) POWER AI (4) GRILL AJ (5) COMBINBATION AF (6) 1.0 KG AG (7) MORE AH (8) LESS AB (9) STAND/TIMER AC (10) CLOCK AD (11) 0.1 KG AE (12) 1 SEC...
  • Page 36 DIGITAL PROGRAMMER CIRCUIT PARTS LIST Ref.No. Part No. Part name & Description Pcs/Set Remarks AEFB22EP20TL BUZZER 2.0KHz BZ210 AECETM1C471A AL CHEM CAPACITOR 470µF/16V AECESS1C220A AL CHEM CAPACITOR 22µF/16V AECEUT2W100F AL CHEM CAPACITOR 10µF/450V/105ºC (EXC EPT WNT) ECEUT2D470F AL CHEM CAPACITOR 47µF/200V/105˚C (WNT) AECESS1H010A...

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