Maytag MMV6178AAB Service Manual
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Maytag MMV6178AAB Service Manual

Maytag MMV6178AAB Service Manual

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CAUTION
BEFORE SERVICING THE UNIT, READ THE
SAFETY PRECAUTIONS IN THIS MANUAL.

Microwave Oven

Service Manual
MMV6178AAB
MMV6178AAQ
MMV6178AAS
MMV6178AAW

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Summary of Contents for Maytag MMV6178AAB

  • Page 1: Microwave Oven

    Microwave Oven Service Manual MMV6178AAB MMV6178AAQ MMV6178AAS MMV6178AAW CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

  • Page 2: Safety Precautions

    CAUTION SAFETY PRECAUTIONS PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY a. Do not operate or allow the oven to be operated with the door open. b. Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source, and make repairs as necessary;...

  • Page 3: Table Of Contents

    FOREWORD Read this Manual carefully. Failure to adhere to or observe the information in this Manual may result in exposing yourself to the Microwave Energy normally contained within the oven cavity. MODEL MMV6178AAB MMV6178AAQ MMV6178AAS MMV6178AAW TABLE OF CONTENTS (Page)

  • Page 4: Specifications

    SPECIFICATIONS Rated Power Consumption - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1500W maximum (Microwave oven only) Microwave Output - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 950W (IEC60705) Adjustable 95W through 950W, 10 steps Frequency - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2450 MHz ±...

  • Page 5: Cautions

    CAUTIONS Unlike other appliances, the microwave oven is MICROWAVE RADIATION high-voltage and high-current equipment. Personnel should not be exposed to the Though it is free from danger in ordinary use, microwave energy which may radiate from the extreme care should be taken during repair. magnetron or other microwave generating device if it is improperly used or connection.

  • Page 6: Installations

    INSTALLATIONS BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY. PRECAUTIONS ON INSTALLATION A. Plug the power supply cord into a 120V AC, 60Hz, single-phase power source with a capacity of 15A or 20A. B. Avoid placing the unit in a location where there is direct heat or splashing water.

  • Page 7: Operating Instructions

    OPERATING INSTRUCTIONS CONTROL PANEL For Model: MMV6178AAB MMV6178AAQ MMV6178AAS MMV6178AAW...

  • Page 8: Control Panel Instructions

    CONTROL PANEL INSTRUCTIONS 1. DISPLAY: The Display includes a clock and 15. MELT: Touch this pad to melt Butter, Chocolate, indicators to tell you time of day, cooking time Cheese, Marshmallow. settings and cooking functions selected. 16. Add 30 SEC.: Touch this pad to set and start 2.

  • Page 9: Overall Circuit Diagram

    OVERALL CIRCUIT DIAGRAM SCHEMATIC DIAGRAM (I) *Check the Model No. For Model: MMV6178AAB MMV6178AAQ MMV6178AAS MMV6178AAW...

  • Page 10: Schematic Diagram (Ii)

    SCHEMATIC DIAGRAM (II) *Check the Model No. (ADD Noise filter) For Model: MMV6178AAB MMV6178AAQ MMV6178AAS MMV6178AAW DISPLAY ERROR MODE THERMISTOR OPEN THERMISTOR SHORT FOR COOKING THERMISTOR SHORT AFTER COOKING SENSOR OPEN DAMPER SWITCH SENSING ERROR...

  • Page 11: Matrix Circuit For Touch Key Board

    MATRIX CIRCUIT FOR TOUCH KEY BOARD For Model: MMV6178AAB MMV6178AAQ MMV6178AAS MMV6178AAW...

  • Page 12: General Information For Service

    GENERAL INFORMATION FOR SERVICE GENERAL PRECAUTIONS IN USE FEATURES AND SPECIFICATIONS FEATURES A. Never operate the unit when it is empty. Operating the oven with no load may shorten the A. The safety systems incorporated in this model are: life of the magnetron. Whenever cooking dry foods (1) Primary interlock switch (dried fish, bread, etc.) or a small amount of food, (2) Secondary interlock switch...

  • Page 13: Service Information

    SERVICE INFORMATION PRECAUTIONS AND REPAIR SERVICE TIPS PRELIMINARY (3) Do not operate the unit until it is completely A. SINCE NEARLY 2,100 VOLTS EXISTS IN SOME repaired, if any of the following conditions exist. CIRCUITS OF THIS UNIT REPAIRS SHOULD BE The unit must not be operated.

  • Page 14: Microwave Leakage Test

    MICROWAVE LEAKAGE TEST CAUTIONS MEASURING MICROWAVE ENERGY LEAKAGE • Be sure to check microwave leakage prior to servicing the oven if the oven is operative prior to • Pour 275±15cc of 20±5°C(68±9°F) water in a beaker servicing. which is graduated to 600 cc, and place the beaker •...

  • Page 15: Measurement With The Outer Case Removed

    MEASUREMENT WITH THE OUTER CASE NOTE WHEN MEASURING REMOVED (1) Do not exceed meter full scale deflection. (2) The test probe must be removed no faster than (1) When you replace the magnetron, measure for 1 inch/sec (2.5cm/sec) along the shaded area, microwave energy leakage before the outer case otherwise a false reading may result.

  • Page 16: Disassembly Instructions

    DISASSEMBLY INSTRUCTIONS IMPORTANT NOTES: (4) Remove 3 screws securing the circuit board. UNIT MUST BE DISCONNECTED FROM ELEC- TRICAL OUTLET WHEN MAKING REPAIRS, RE- PLACEMENTS, ADJUSTMENTS AND CONTIN- UITY CHECKS. WAIT AT LEAST ONE MINUTE, UNTIL THE HIGH VOLTAGE CAPACITOR IN THE HIGH VOLTAGE POWER SUPPLY HAS FULLY DISCHARGED.
  • Page 17 HOW TO REMOVE THE F.P.C. CONNECTOR HOW TO INSERT THE F.P.C. CONNECTOR Follow the steps below as illustrated in Figures 4 Follow the steps below as illustrated in Figures 6 and 5 to remove the F.P.C. connector. and 7 to insert the F.P.C. connector. (1) Hold the edges of the plastic fastener with (1) Insert the F.P.C.
  • Page 18 B. REMOVING THE OUT CASE(Figure 8) (1) Remove the vent grille by removing two screws securing it to the out case. (2) Remove two screws securing it to the air duct. (3) Remove the mounting plate by turning the screws (1 or 2 screws) securing it to the out case.
  • Page 19 C. REMOVING THE DOOR INTERLOCK SWITCHES (Figures 9, 10) (1) Disconnect the wire leads from the interlock switches. (2) Remove two screws securing the Latch Board. (3) Make necessary replacements and check microwave energy leakage according to Latch Board “ADJUSTMENT PROCEDURE” on page 7-12. Primary Interlock Switch Latch Board...
  • Page 20 D. REMOVING MAGNETRON NOTES: • When removing the magnetron, make sure that its (Figures 11 Through 13b) dome does not hit any adjacent parts, or it may be (1) Remove the vent grille by loosening two screws. damaged. (Figure 11) (2) Remove the outcase.
  • Page 21 E. REMOVING STIRRER FAN F. REMOVING DOOR (Figure 16) (Figures 14 and 15) (1) Remove the vent grille by two screws securing it to (1) Remove two screws securing it to the oven the outcase loosening. upper plate by using drive screw. (2) Lift up and draw the door.
  • Page 22 H. ASSEMBLING DOOR J. REPLACING THE HUMIDITY SENSOR (1) When mounting the door assembly to the oven (For sensor model only) assembly, be sure to adjust the door assembly (1) Remove the sensor by removing two screws parallel to the chassis. Also adjust so the door has no securing it to the air duct.
  • Page 23 L. REMOVING THE TURNTABLE MOTOR M. REMOVING CONVECTION HEATER (1) Remove the turntable. AND THERMISTOR (Figure 23) (2) Remove the turntable shaft VERY CAREFULLY (1) Remove the out case. with a slotted screwdriver. (Figure 21) (2) Remove the air duct by removing six screws (3) Remove the base plate by removing 7 screws securing it to the oven front plate, guide air and securing it to the oven cavity.

  • Page 24: Interlock System

    INTERLOCK SYSTEM INTERLOCK MECHANISM The door lock mechanism is a device which has been specially designed to eliminate completely microwave activity when the door is opened during cooking and thus to prevent the danger resulting from the microwave leakage. ADJUSTMENT PROCEDURES CHECK THE DOOR LATCH AND SWITCH To avoid possible exposure to microwave energy CLOSING.
  • Page 25 TEST THE LATCH AND SWITCH SEQUENCE (5) Open the oven door slowly. Watch the door latch, (7) When you achieve the proper sequence of the Secondary Switch. Release Rod and Lever switches in Steps 5 and 6, tighten the latch board on the switches to make sure they are zero to the screws at that point.

  • Page 26: Interlock Continuity Test

    INTERLOCK CONTINUITY TEST A. PRIMARY INTERLOCK SWITCH TEST B. SECONDARY INTERLOCK SWITCH TEST When the door is opened slowly, an audible click Disconnect the wire lead from the secondary should be heard at the same time or successively switch. at intervals and the latches should activate the Connect the ohmmeter leads to the common switches with an audible click.

  • Page 27: Test And Checkout Procedures And Trouble Shooting

    TEST AND CHECKOUT PRECEDURES AND TROUBLESHOOTING Filament Winding - CAUTIONS - Secondary Winding - DISCONNECT THE POWER SUPPLY CORD FROM THE WALL OUTLET WHENEVER REMOVINGING THE CABINET FROM THE UNIT. PROCEED WITH THE TESTS ONLY AFTER DISCHARGING THE HIGH VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER.
  • Page 28 COMPONENTS TEST PROCEDURES RESULTS HIGH-VOLTAGE 1. Remove wire leads. CAPACITOR 2. Measure resistance. (ohm meter scale: Normal: Rx1000) Momentarily indicates several ohm, and (1) Terminal to terminal then gradually returns to infinite Ohm-meter Figure 25-a Normal: Infinite. (2) Terminal to case Ohm-meter Figure 25-b HIGH-VOLTAGE...
  • Page 29 FPC connector are properly engaged with hooks on the plastic fastener. MATRIX CIRCUIT FOR TOUCH KEY BOARD FPC CONNECTOR CONNECTOR(KEY CON) For Model MMV6178AAB MMV6178AAQ MMV6178AAS MMV6178AAW Figure 28 Figure 27 1. Remove the 3 pin connector from PCB.
  • Page 30 COMPONENTS TEST PROCEDURES RESULTS FAN MOTOR 1. Remove wire leads. Normal: 2. Measure resistance. Approximately DAMPER MOTOR (ohm meter scale: Rx1) Damper CIRCULATION 35-55 2.5-3.5 25-40 MOTOR Kohm Abnormal: Infinite or several. VENTILATION MOTOR 1. Remove wire leads. Normal: 2. Measure resistance. Approximately 25 to 45 ohm (ohm meter scale: Rx1) SYNCHRONOUS...

  • Page 31: Checkout Procedures

    COMPONENTS TEST PROCEDURES RESULTS POWER RELAY 8 1. Measure continuity. LEVEL (ohm meter scale: Rx1) 2. Remove the lead wires and operate 4 sec 18 sec oven at power level 1 through power 6 sec 16 sec level 10. 8 sec 14 sec 10 sec 12 sec...
  • Page 32 (2) CHECKOUT PROCEDURES FOR RELAY. - PROBLEM (A) - FAN motor and oven lamp turn on without touching START key when the door is closed. Remove the mate connector of I/O GOOD CON from the circuit board. Does the unit still operate? Replace the Defective circuit board...
  • Page 33 (3) CHECKOUT PROCEDURES FOR CIRCUIT BOARD The following symptoms indicate a defective circuit 6) Wrong figures appear. board. 7) The figures of all digits. 1) The start function fails to operate but the high 8) Some of the indicators do no flicker light up. voltage Systems, the interlock switches, the door 9) The clock does not keep time properly.
  • Page 34 7-22...
  • Page 35 7-23...
  • Page 36 7-24...
  • Page 37 7-25...
  • Page 38 7-26...

  • Page 39: Exploded View

    #EV# EXPLODED VIEW DOOR PARTS FOR MODEL: MMV6178AAB Serial Number ldentification MMV6178AAQ (Figure Check First & Second) MMV6178AAW ex) 1 0 1005 1000 W150 1011 1004 1003 1006 1008 1007 1019 W109 1012 W105 1009 FOR MODEL: MMV6178AAS 1005 1011...

  • Page 40: Controller Parts

    #EV# CONTROLLER PARTS FOR MODEL: MMV6178AAB Check the rating label of Model Serial No. MMV6178AAQ and order SVC parts according to the Serial No. MMV6178AAW 2004 2381 2002 W130 2000 2006 2008 * Check the 2018 Serial No. * 07...
  • Page 41 #EV# CONTROLLER PARTS FOR MODEL: MMV6178AAB Check the rating label of Model Serial No. MMV6178AAQ and order SVC parts according to the Serial No. MMV6178AAW 2004 2381 2002 W130 2000 2006 2008 * Check the * 07 Serial No. FOR MODEL: MMV6178AAS...

  • Page 42: Oven Cavity Parts

    #EV# OVEN CAVITY PARTS For Model MMV6178AAB W142 W108 W142 W108 MMV6178AAS W138 For Model W138 3010 MMV6178AAW 3031 MMV6178AAQ 3001 3024 W105 3029 3009 3103 W202 3005 W178 6000 3045 3037 3032 3006 W121 3011 3025 3026...

  • Page 43: Latch Board Parts

    #EV# LATCH BOARD PARTS 4001 4000 4002 W111 4003 4002 4004...
  • Page 44 #EV# INTERIOR PARTS (I) 3018 3048 W177 W109 W110 W101 5052 W109 3034 5003 5012 3002 3012 5007 3008 5002 5000 3204 5018 W101 5023 3203 W109 5009 5024 5701 5049 5035 5008 W109 5062 5029 3206 W121 W125 W141 W105 W124 3207...
  • Page 45 #EV# INTERIOR PARTS (II - I) Check the rating label of Model Serial No. and order SVC parts according to W150 the Serial No. W117 W117 5011 3021 5045 5056 W109 3045 3051 3033 W109 5006 W109 5016 W150 W109 5037 5010 3027...
  • Page 46 #EV# INTERIOR PARTS (II - II) Check the rating label of Model Serial No. and order SVC parts according to the Serial No. W117 W150 W117 5045 5056 5011 3021 3045 W109 * Check the Serial No. 3051 2018 W109 3033 5006 W109...
  • Page 47 #EV# INSTALLATION PARTS 6008 6011 6010 6009 VINYL...
  • Page 48 P/NO : 3828W5S4605 Printed in Korea...

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