Samsung SMH7178STD Service Manual Download Page 1

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MICROWAVE OVEN

SERVICE

Manual

MICROWAVE OVEN

CONTENTS

1. Precaution

2. Speciﬁcations

3. Operating Instructions

4. Disassembly and Reassembly

5. Alignment and Adjustments

6. Troubleshooting

7. Exploded Views and Parts List

8. PCB Diagrams

9. Schematic Diagrams

10. Reference

SEA

BASIC : SMH7178STD

MODEL : SMH7178STE

Summary of Contents for SMH7178STD

Page 1: ...NTS 1 Precaution 2 Speciﬁcations 3 Operating Instructions 4 Disassembly and Reassembly 5 Alignment and Adjustments 6 Troubleshooting 7 Exploded Views and Parts List 8 PCB Diagrams 9 Schematic Diagrams 10 Reference SEA BASIC SMH7178STD MODEL SMH7178STE ...

Page 2: ...4 8 1 Removal of Control Box 13 4 3 4 Removal of P C B Assembly 13 5 Alignment and Adjustments 14 5 1 High Voltage Transformer 14 5 2 Low Voltage Transformer 14 5 3 Magnetron 14 5 4 High Voltage Capacitor 15 5 5 High Voltage Diode 15 5 6 Main Relay and Power Control Relay 15 5 7 Adjustment of Primary Switch Door Sensing Switch and Monitor Switch 15 5 8 VENT EXHAUST BLOWER MOTOR 16 5 9 THERMAL CUTO...

Page 3: ... B Diagrams 30 8 2 P C B Parts List 31 8 2 P C B Parts List continued 32 9 Schematic Diagrams 33 9 1 Schematic Diagrams 33 10 Reference 34 10 1 Model name standard 34 10 2 Customer inquiry cases and countermeasures 35 10 2 Customer inquiry cases and countermeasures Continued 36 Contents ...

Page 4: ...ction within the microwave generating compartments check the magnetron wave guide or transmission line and cavity for proper alignment integrity and connections d Any defective or misadjusted components in the interlock monitor door seal and microwave generation and transmission systems shall be repaired replaced or adjusted by procedures described in this manual before the oven is released to the...

Page 5: ...ches while repairing an MWO 11 To avoid any possible radiation hazard replace parts in accordance with the wiring diagram Also use only the exact replacements for the following parts Primary and secondary interlock switches interlock monitor switch 12 If the fuse is blown by the Interlock Monitor Switch Replace all of the following at the same time Primary door sensing switch and power relay as we...

Page 6: ...and discharge the high voltage capacitor See Figure 1 1 2 The high voltage capacitor remains charged about 30 seconds after disconnection Short the negative terminal of the high voltage capacitor to to the oven chassis Use a screwdriver 3 High voltage is maintained within speciﬁed limits by close tolerance safety related components and adjustments If the high voltage exceeds the speciﬁed limits ch...

Page 7: ...R OPERATING FREQUENCY MAGNETRON COOLING METHOD OUTSIDE DIMENSIONS NET WEIGHT SHIPPING WEIGHT 99 MINUTES 99 SECONDS 120V 60Hz AC MICROWAVE 1 650W FROM 100 TO 1100W 10 LEVEL POWER IEC 705 TEST PROCEDURE 2 450MHz OM75P 10 ERHN COOLING FAN MOTOR 2914 16 W x 1515 16 H x 1511 32 D mm 58 4 lbs 64 4 lbs ...

Page 8: ...an high 7 Power Level Press this pad to set a power level other than high 8 Clock am pm Sets current time 9 Light On Night Off Button 10 Turntable On Off Button 11 One Minute Press once for every minute of cooking at High power 12 My Choice Press to set non cooking feature 13 Custom Cook Press twice to program your favorite recipe Press once to cook with that recipe 14 Start Press to start cooking...

Page 9: ... 5 Door Door Latches Handle Ventilation Holes Oven Light Safety Interlock Holes Control Panel Intake Holes Glass Tray Guide Roller 398mm 758 9mm 417 25mm 405mm 3 2 Features External Views ...

Page 10: ... 6 Glass tray Roller guide ring 3 3 Accessary ...

Page 11: ...to cabinet arrangements such as an island or peninsula It must be mounted to both a top cabinet and wall VENT BLOWER The vent or exhaust blower is located at the top of the oven It is shipped for vertical exhaust but can be changed to rear exhaust or recirculating See installation instrustions on how to change and or blower section on how to remove COOKTOP LIGHTS One 40 watt screw base incandescen...

Page 12: ...n will automatically turn off when the internal parts are cool If may stay on for 30 minutes or more after the cooktop and microwave controls are turned off GRILLE REMOVAL The top full width grille is removable for service to some components such as oven light cavity T C O vent motor capacitor and fuse TO REMOVE GRILLE 1 Disconnect oven power 2 Remove screws 2 from grille outer case 3 Lift off gri...

Page 13: ...t may be damaged NOTE2 When replacing the magnetron be sure to remount the magnetron gasket in the correct position and make sure the gasket is in good condition 1 Discharge the high voltage capacitor 2 Disconnect all the leads 3 Remove the mounting bolts 4 Reconnect the leads correctly and ﬁrmly PRECAUTION Servicemen should remove their watches when ever working close to or replacing the magnetro...

Page 14: ...ragile Then remove the door assembly 4 3 2 Removal of Door E Following the procedure as shown in the ﬁgure insert and bend a thin metal plate between Door E and Door A until you hear the tick sound Insertion depth of the thin metal plate should be 0 5mm or less 4 3 3 Removal of Key Door Spring Remove pin hinge from Door E Detach spring from Door E and key door Door A Door C DOOR E Spring ...

Page 15: ...the door has no play between the inner door surface and oven front surface If the door assem bly is not mounted properly microwave energy may leak from the space between the door and oven 3 Do the microwave leakage test After replacement of the defective component parts of the door reassemble it and follow the instruc tions below for proper installation and adjustment so as to prevent an excessive...

Page 16: ... motor screws 1 and lift up stirrer motor after turn left The stirrer is located on the upper side of the cavity The oven uses a top feed wave guide 1 Disconnect power and open the door 2 Remove the clip and turn the stirrer cover left 3 Remove stirrer cover and the stirrer will come with it 4 Replace the clip if the clip head broken CLIP COVER STIRRER STIRRER ASSEMBLY COVER STIRRER STIRRER MOTOR ...

Page 17: ...nect the connectors from the control circuit board 4 8 2 Removal of P C B Assembly 1 Pull the lever end of the plastic fastener and remove the Flexible Printed Circuit FPC of membrane panel 2 Remove screws 3 securing the control circuit board 3 Lift up the control circuit board from the Ass y control box 4 When reconnecting the FPC connector make sure that the holes on the connector are properly e...

Page 18: ... open ﬁlament or a shorted magnetron To diagnose an open ﬁlament or shorted magnetron 2 Isolate the magnetron from the circuit by disconnecting its leads 3 A continuity check across the magnetron ﬁlament terminals should indicate one ohm or less 4 A continuity check between each ﬁlament terminal and magnetron case should read open 1 The low voltage transformer is located on the control circuit boa...

Page 19: ... Latch Body to the oven assem bly adjust the Latch Body by moving it so that the oven door will not have any play in it Check for play in the door by pulling the door assembly Make sure that the latch keys move smoothly after adjustment is completed Completely tighten the screws holding the Latch Body to the oven assembly 4 Reconnect to Monitor switch and check the continu ity of the monitor circu...

Page 20: ...ould be much slower TO TEST THE CAPACITOR 1 Remove grille discharge capacitor and disconnect one capacitor lead 2 Make appropriate capacitor check with analog meter needle should rise then fall cap is charging then discharging TO TEST BLOWER WINDINGS 1 Disconnect power and remove grille 2 Open control panel and discharfe capacitor 3 Disconnent two wires to run capacitor Continuity test across the ...

Page 21: ... the oven cavity beside exhaust duct with a temperature rating of 248OF 120OC and is non resetable The cutout is tightly held to the top of the oven cavity by duct upper 5 9 2 Replacement of Flame Sensor Disconnect oven power Remove Grille Panel outer 1 Remove screws 3 securing the duct upper 2 Loft up the duct upper from the cavity 3 Disconnect two wire leads 4 Press the top of the thermal cutout...

Page 22: ... is during an overheat condition It will be normally open when checked with an ohmmeter 5 9 4 Magnetron Thermal Cutout THIS COMPONENT REQUIRE REMOVAL OF MICROWAVE OVEN FROM INSTALLATION FOR SERVICING During a ﬁre on the stove the heat could be intense enough to close the Hood Thermal Cutout and force the fan to run While at moderate high temperature we do want it to run however during a ﬁre it is ...

Page 23: ...play Numbers approximate 15 185 Normal verify with detection test 213 or Higher Sensor failed to open sensor unplugged wiring or smart board Less then 6 shorted sensor or smart board NOTE Only heater terminals H Black and Red leads can be checked with ohmmeter 30Ω CAUTION DO NOT ATTEMPT TO CHECK SENSOR TERMINALS White and Orange leads CAN DAMAGE SENSOR Power Defrost Sensor Reheat Pause Cancel pota...

Page 24: ...water again with the thermometer and measure the temperature T2 5 Subtract T1 from T2 This will give you the water temperature rise T 6 The output power is obtained by the following formula Output Power 4 187 x 1000 x T 0 55xMcx T2 T1 38 Heating Time sec 41 Counting Time sec 4 187 Coefﬁcient for Water 1000 Water cc T Temperature Rise T2 T1 To Room Temperature Mc Cylindrical borosilicate glass weig...

Page 25: ...or seam is taken near a corner of the door keep the probe perpendicular to the areas making sure that the probe end at the base of the cone does not get closer than 5cm to any metal If it gets closer than 5cm erroneous readings may result 5 Measured leakage must be less than 4mW cm2 after repair or adjustment Maximum allowable leakage is 5mW cm2 4mW cm2 is used to allow for measurement and meter a...

Page 26: ...mer starts countdown but no microwave oscillation No heat while oven lamp and fan motor turn on 1 Off alignment of latch switches 2 Open or loose connection of high voltage circuit especially magnetron ﬁlament circuit NOTE Large contact resistance will bring lower magnetron ﬁlament voltage and cause magnetron to lower output and or intermittent oscillation 3 Defective high voltage components H V T...

Page 27: ...e turntable motor Replace turntable motor Oven stops operation during cooking 1 Open or loose wiring of primary interlock switch 2 Operation of thermal cutout Magnetron Adjust door and latch switches Sparks 1 Metallic ware or cooking dishes touching on the oven wall 2 Ceramic ware trimmed with gold or silver powder also causes sparks Inform the customer Do not use any type of cookware with metalli...

Page 28: ... M015 M001 M035 M029 M021 M023 M017 H018 P109 M040 M039 M041 M206 P059 M050 B002 B001 B013 U004 U007 U001 P122 P123 M038 P121 M048 M155 M036 U003 P012 P006 M024 M060 P090 P087 P088 P091 P089 C004 C133 D049 C082 C005 C009 C001 P156 R066 C073 C073 C089 D040 D005 D004 D006 P125 P007 P007 H032 P098 P178 P112 P179 P113 P101 P117 P099 M067 P208 P104 P100 P102 M068 P106 M149 M149 D019 D002 D024 D041 D037...

Page 29: ... SA 1 2 P014 DE72 40022A DAMPER MAIN SECC W28 L650 OTR4 T0 1 SA 1 1 M060 DE92 90505E ASSY HARD WARE SMH7175 1 SA 1 2 P087 DE60 10111A SCREW LAG MSWR W1 4X50 1 SA 1 2 P088 DE60 20022A BOLT TOGGLE MSWR W3 16X75 3 SA 1 2 P089 DE60 20066A BOLT FLAT UNF1 4 L110 MSWR10 OTR6 3 SA 1 2 P090 DE60 30022A NUT TOGGLE SBC1 ZPC2 WHT 3 SA 1 2 P091 DE63 10011A GROMMET MS DACB 16 2 SA 1 1 P032 DE92 90508A ASSY HOLD...

Page 30: ...125V 0 1A 60GF SPNO 1 SA 1 3 H032 DE31 10154C MOTOR DRIVE M2CK59ZT69 H 120V60HZ 1 SA 1 3 W023 DE39 00253A WIRE HARNESS CAM JVM 1860 1 SA 1 3 P112 DE61 00118A BRACKET CAM PLATE JVM 1860 SCP T2 0 W60 1 SA 1 3 P113 DE72 00145A CAM LOUVER JVM 1860 POM KEPITAL FE 22 1 SA 1 2 P097 DE97 00371B ASSY DUCT UPPER SUB JMV8186 HUMIDITY SE 1 SA 1 3 U003 DE47 00006A HOLDER LAMP 250V 75W 250X187 2POLE OTR 1 SA 1 ...

Page 31: ...RACKET BARRIER GR JVM 1860 SECC T0 5 1 SA GRILLE 1 3 P117 DE61 00672A BRACKET COVER GRILLE SMH7178 SECC T1 2 W 1 SNA 1 3 P208 DE64 01296A CHASSIS GRILLE SMH7178 STS430 4 T0 5 W7 1 SNA 1 1 M035 OM75P 10 ERHN ASSY MAGNETRON OM75P 10 ERHN 1 SA 7 2 Main Parts List S N A SERVICE NOT AVAILABLE ...

Page 32: ...DOOR A SMH7178 PC T2 5 L619 W327 BLK 1 SA 1 3 D040 DE64 01299A CHASSIS DOOR U SMH7178 STS430 4 T0 5 W 1 SNA 1 3 D041 DE64 01300A CHASSIS DOOR L SMH7178 STS430 4 T0 5 W 1 SNA 1 1 C082 DE94 01120D ASSY CONTROL BOX 120V 60HZ SMH7178STE XA 1 SA 1 2 C089 DE39 40673A WIRE HARNESS H 120V60HZ OTR6 ALL MODEL G 1 SA 1 2 D090 DE63 00289A EARTH SPRING SMH7178 HSWR T0 4 OD5 L9 9 1 SNA 1 2 C009 DE64 00766B WIND...

Page 33: ...PC BLK MSWR 1 SA P OUTER 1 1 6006 001170 SCREW TAPPING TH WT TC M4 L10 ZPC YEL SWRCH18A 1 SA P CORD 1 1 6006 001175 SCREW TAPPING WS TH M4 L8 ZPC YEL 1 SNA ASSY HVD 1 1 DE60 10045A SCREW TAPPING FEFZY PH M3 L6 2 SA MGT TCO 1 1 DE60 10051A SCREW TAPPING MSWR PH M4 L6 1 SA S T MOTOR 1 1 DE60 10051A SCREW TAPPING MSWR PH M4 L6 1 SA TURNTABLE MOTOR 1 1 DE60 10062A SCREW TAPPING FEFZB TH M4 L12 1 SA BK...

Page 34: ... 5V R 40 2K 2K R 13 C 10 100nF 24V 47K R 34 100nF C 15 R 30 180 330 R 29 LV T 1 S LV 5574U 47K T R 05 K R C 246M K R C 246M T R 04 R 33 4 7uF C 12 5V R 10 2 2K 470 R 02 5V 5V 1K R 19 C 13 10nF F 1 1N4148M D05 F T R F 3AA024E R Y 02 UZ5 1B S B ZD05 2K R 39 D09 R 38 2K 1N4148M D10 1N4148M R 01 470 P T C 1 270M D08 1N4148M D15 1T 4 ZNR 1 10D471 R 22 470 R Y 09 F T R F 3AA024E 100K R 27 K R C 246M T R...

Page 35: ...3 2MM 19 SNA R04 R06 R11 R13 R15 R 20 R21 R28 R35 R43 1 2 2001 000780 R CARBON 470OHM 5 1 8W AA TP 1 8X3 2MM 2 SNA R01 R02 1 2 2001 000786 R CARBON 47KOHM 5 1 8W AA TP 1 8X3 2MM 4 SNA R31 R34 1 2 2004 000218 R METAL 10Kohm 1 1 8W AA TP 1 8x3 2mm 2 SNA R23 R24 1 2 2004 000517 R METAL 200Kohm 1 1 8W AA TP 1 8x3 2m 1 SNA R26 1 2 2004 001978 R METAL 300ohm 1 1 8W AA TP 1 8x3 2mm 1 SNA R45 1 2 2004 004...

Page 36: ...07SS10 SEA 1 SA DSP1 1 2 DE09 00499A IC MICOM TMP87CM14F CHUN SMH7178 64 PIN 5V QFP TRAY 20 85 1 SNA IC01 1 2 DE13 20009A IC KA7533 DIP 1 SNA IC03 1 1 DE26 20144A TRANS L V SLV 5574U 120V 60HZ AC17V 2 7V 1 SA LVT1 1 1 DE30 20016A BUZZER CBE2220BA STICK 1 SNA BZ01 1 2 DE39 60001A WIRE SO COPPER PI0 6 SN T 52MM TAPING_WIRE 19 SNA J01 J19 1 2 DE41 00309A PCB MAIN RAS OTR7HV FR 1 1 T1 6 197 197 2 ARRA...

Page 37: ... 33 9 Schematic Diagrams 9 1 Schematic Diagrams This Document can not be used without Samsung s authorization ...

Page 38: ...ON C RC USA RV CONVECTION BUILT IN B RB USA RV BUILT IN USA Junior SJ SJ USA Junior MWO USA OTR SM SOLO H SMH USA OTR SOLO CONVECTION V SMV USA OTR CONVECTION EUROPE Ep oxy Cavity M SOLO 1 M1 EUROPE SOLO EPOXY CAVITY GRILL 2 M2 EUROPE GRILL EPOXY CAVITY EUROPE Ce ramic Enamel CE SOLO 1 CE1 EUROPE SOLO CERAMIC ENAMEL GRILL 2 CE2 EUROPE GRILL CERAMIC ENAMEL EUROPE Quartz GRILL G2 G2 EUROPE Quartz GR...

Page 39: ...IUM LOW This function is used to cook the food slowly Close the door completely Press the Cancel but ton Press the Start button Contact the nearest Samsung after sales service cen ter Ground Ground problem may happen when the oven is placed in a humid area and the over is not grounded Ground is not provided by an extended electric outlet If the oven is placed in a humid area buy an electric wire i...

Page 40: ...such as herbal remedies are not removed Error Errors are classiﬁed into the case which is out of order and the case which is not out of order Clean the inside of the oven Remove strange smell through the Deodorant button If the strange smell still remains place a piece of lemon on the turntable and operate the oven for 5 minutes by pressing the Deodorant button However the smells produced from the...

Page 41: ...al is a property of Samsung Electronics Co Ltd Any unauthorized use of Manual can be punished under applicable International and or domestic law Samsung Electronics Co Ltd June 2005 Printed in Korea Code No DE68 03949A ...

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