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Electrolux EM1760X, Service Manual

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Electrolux EM1760X Service Manual Download Page 19

SOI  01.05  FV 

19/33 

599 36 78-06 

 

   

 

 

TEST PROCEDURES

 

 

PROCEDURE 

LETTER

 

 

COMPONENT TEST

 

 

 

If a reading of the line voltage was obtained (step 7) but the motor was not 
turning then it is faulty and should be replaced. If the meter indicated that the 
no supply was present then the winding to the motor should be checked for 
continuity or other circuit checks should be made, i.e. relays, switches.

 

 

 

J 

TOUCH CONTROL PANEL ASSEMBLY TEST

 

 

 

 

The touch control panel consists of circuits including semiconductors such as 
LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper 
maintenance can not be performed with only a voltmeter and ohmmeter. 
In this service manual, the touch control panel assembly is in three units, 
Control unit, Switch Unit, and LED Unit. Troubleshooting by unit replacement is 
described according to the symptoms indicated. 
Control Panel. 
The following symptoms indicate a defective control unit. 
1.  Switch Unit.   

NOTE:   Check switch unit lead wire harness connection  

    

  

before 

replacement. 

 

The following symptoms indicate a defective switch unit. Replace the 

 switch 

unit. 

 a) 

 

When touching the keys, a certain key produces no signal at all. 

 b) 

 

When touching a key, two figures or more are displayed. 

 

c) When touching the keys, sometimes a key produces no signal. 

2.  Control Unit 
 

The following symptoms indicate a defective control unit. Replace the 

 

control unit, perform the switch unit test(Procedure K) to determine if 

 

control unit is faulty. 

2-1 In connection with keys. 
 

a) When touching a key, a certain group of keys do not produce a signal. 

 

b) When touching a key, no keys produce a signal. 

2-2.In connection with indicators. 
 a) 

 

At a certain digit, all or some dots do not light up. 

 

b) At a certain digit, brightness is low. 

 

c) Only one indicator does not light up. 

 

d) The corresponding dots of all digits do not light up; or they continue to  

  light 

up. 

 

e) Wrong figure appears. 

 

f) A certain group of indicators do not light up. 

 

g) The figure of all digits flicker. 

 

h) When touching a tact switch, the control unit does not respond. 

2-3.Other possible problems caused by defective control unit. 
 

a) Buzzer does not sound or continues to sound. 

 

b) Clock does not operate properly. 

 

c) Cooking is not possible. 

3. LED Unit 
 

a) No backlight behind display. 

 

b) Dull backlight behind display.

 

 

 
 
 
 
 

Summary of Contents for EM1760X

Page 1: ...so Lino Zanussi 30 Publication No I 33080 PORCIA PN ITALY 599 36 78 06 Tel 39 0434 394850 Fax 39 0434 394096 SOI Edition 01 2005 EN SERVICE FV Microwave Oven Compact Solo MC1751E MC1761E EU MC1751E MC1761E UK EMS1750X EM1760X UK QN4025 QN4026 SCANDINAVIA JMW1051 JMW1061 A D MOA4217 D K ...

Page 2: ...SOI 01 05 FV 2 33 599 36 78 06 ...

Page 3: ... SPECIFICATIONS 6 APPEARANCE VIEW 7 OPERATING SEQUENCE 10 FUNCTION OF IMPORTANT COMPONENTS 12 TROUBLESHOOTING CHART 13 TEST PROCEDURE 14 CONTROL PANEL ASSEMBLY 22 COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE 24 MICROWAVE MEASUREMENT 30 TEST DATA A GLANCE WIRING RE WIRING 31 SCHEMATIC DIAGRAMS 32 PICTORIAL DIAGRAM 33 ...

Page 4: ...engineers carefully study the entire text of this manual so they will be qualified to render satisfactory customer service WARNING Note The parts marked are used at voltage more than 250V Schematic Diagrams WARNING Never operate the oven until the following points are ensured A The door is tightly closed B The door and oven hinges are not defective C The door packing is not damaged D The door is n...

Page 5: ... Reconnect all leads removed from components during testing 2 Replace the outer case cabinet 3 Reconnect the supply 4 Run the oven Check all functions Microwave ovens should not be run empty To test for the presence of microwave energy within a cavity place a cup of cold water on the oven turntable close the door and set the power to HIGH and set the microwave timer for two 2 minutes When the two ...

Page 6: ...meter 272mm Jog Touch Control System Clock 1 00 12 59 or 0 00 23 59 12HR or 24HR setting Microwave Power for Variable Cooking Repetition Rate HIGH Full power throughout the cooking time MEDIUM HIGH approx 70 of Full Power MEDIUM approx 50 of Full Power MEDIUM LOW approx 30 of Full Power LOW approx 10 of Full Power Stir AUTOMATIC button Turn over MICROWAVE POWER LEVEL button Weight STOP button Micr...

Page 7: ...eration Stir Turn oven Weight Microwave power level Cooking in progress 3 TIMER WEIGHT knob 4 MICROWAVE POWER LEVEL button 5 AUTOMATIC PROGRAMMES button Press to select one of the 12 automatic programmes 6 START QUICK button 7 STOP button 8 DOOR OPEN button Turntable Roller stay Seal packing 1 Front trim 2 Oven lamp 3 Control panel 4 Door opening button 5 Waveguide cover 6 Oven cavity 7 Seal packi...

Page 8: ... LEVEL button 5 AUTOMATIC PROGRAMMES button Press to select one of the 12 automatic programmes 6 START QUICK button 7 STOP button 8 DOOR OPEN button 1 Digital Display 2 Indicators The appropriate indicator will flash or light up just above each symbol according to the instruction When an indicator is flashing press the appropriate button having the same symbol or carry out the necessary operation ...

Page 9: ...tton 5 AUTOMATIC PROGRAMMES button Press to select one of the 12 automatic programmes 6 START QUICK button 7 STOP button 8 DOOR OPEN button 1 Digital Display 2 Indicators The appropriate indicator will flash or light up just above each symbol according to the instruction When an indicator is flashing press the appropriate button having the same symbol or carry out the necessary operation Stir Turn...

Page 10: ...oked 4 When the cooking time is up a single tone is heard and the relays RY1 RY3 RY4 go back to their home position The circuits to the oven lamp power transformer fan motor and turntable motor are cut off 5 When the door is opened during a cook cycle the switches come to the following condition CONDITION SWITCH CONTACT DURING COOKING DOOR OPEN NO COOKING Monitor switch COM NC Open Closed COM NO C...

Page 11: ...ed to the power transformer intermittently within a 32 second time base through the vary contact The following levels of microwave power are given SETTING NOTE The ON OFF time ratio does not exactly correspond to the percentage of microwave power because approx 3 seconds are needed for heating up the magnetron filament HIGH MEDIUM HIGH MEDIUM MEDIUM LOW LOW Approx Approx Approx Approx ...

Page 12: ...the oven cavity is designed to prevent damage to the oven if the foods in the oven catch fire due to over heating produced by improper setting of cook time or failure of control unit Under normal operation the oven thermal cut out remains closed However when abnormally high temperatures are reached within the oven cavity the oven thermal cut out will open at 125 C causing the oven to shut down The...

Page 13: ...D WIRE HARNESS OPENED WIRE HARNESS OVEN LAMP BLOCKED VENTILATION OPENINGS WRONG OPERATION MIS ADJUSTMENT OF SWITCHES HOME FUSE OR BREAKER NO POWER AT WALL OUTLET BLOKED COOLING FAN Home fuse blows when power cord is plugged into wall outlet 88 88 does not operate in display when power cord is plugged into wall outlet Display does not operate properly when STOP button is touched Oven lamp does not ...

Page 14: ...econd approximately P x t 4 187 calorie is generated On the other hand if the temperature of the water with V ml rises T C during this microwave heating period the calorie of the water is V x T The formula is as follows P x t 4 187 V x T P W 4 187 x V x T t Our condition for water load is as follows Room temperature around 20 C Power supply Voltage Rated voltage Water load 1000 g Initial temperatu...

Page 15: ...s JUDGEMENT The measured output power should be at least 15 of the rated output power CAUTION 1 C CORRESPONDS TO 80 WATTS REPEAT MEASUREMENT IF THE POWER IS INSUFFICIENT B POWER TRANSFORMER TEST WARNING High voltages and large currents are present at the secondary winding and filament winding of the power transformer It is very dangerous to work near this part when the oven is on NEVER make any vo...

Page 16: ...nd must be replaced When the asymmetric rectifier is defective check whether magnetron high voltage rectifier high voltage wire or filament winding of the power transformer is shorted CARRY OUT 4R CHECKS NOTE FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER THE BATTERIES OF THE MEASURING INSTRUMENT MUST HAVE A VOLTAGE OF AT LEAST 6 VOLTS BECAUSE OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN...

Page 17: ...perature of ON condition closed circuit C Temperature of OFF condition open circuit C Indication of ohmmeter When room temperature is approx 20 C Thermal cut out 125 C TC01 This is not reset able type Above 125 C Closed circuit Thermal cut out 125 C TC02 This is not reset able type Above 125 C Closed circuit If incorrect readings are obtained replace the thermal cut out An open circuit thermal cut...

Page 18: ... FOR MOTOR WINDING CAUTION The following procedure requires the oven to be connected to the supply and should only be used if the relevant cold checks for the motor under test are inconclusive 1 CARRY OUT 3D CHECKS 2 Disconnect the leads from the primary of the high voltage transformer Make sure that the leads remain isolated from other oven components and chassis Use insulation tape if necessary ...

Page 19: ...e a defective switch unit Replace the switch unit a When touching the keys a certain key produces no signal at all b When touching a key two figures or more are displayed c When touching the keys sometimes a key produces no signal 2 Control Unit The following symptoms indicate a defective control unit Replace the control unit perform the switch unit test Procedure K to determine if control unit is...

Page 20: ...nd the above method may be used after clearing the control unit to determine if the control unit or switch unit is at fault MC1751E Mc1761E MOA4117 EMS1750X EMS1760X ZM175ST ZM176ST QN4025 QN4026 JMW1051 JMW1061 SW USAGE USAGE 1 Start Quick Start Quick 2 Not Used Not Used 3 Stop Stop 4 Power Level Not Used 5 Not Used Auto Programs 6 Auto Programs Not Used 7 Not Used Not Used 8 Not Used Power Level...

Page 21: ...N 1 The rated AC voltage is not present between Pin No 5 1 of the 3 pin connector A Check supply voltage and oven power cord 2 The rated AC voltage is not present at primary side of low voltage transformer Low voltage transformer or secondary circuit defective check and repair 3 Pattern at a and b are broken Insert jumper wire J1 and solder CARRY OUT 3D CHECKS BEFORE REPAIR 4 Pattern at c and d ar...

Page 22: ...cessary in the control unit Symbol Voltage Application VC 5 0V LSI IC1 3 Synchronizing Signal Circuit The power source synchronizing signal is available in order to compose a basic standard time in the clock circuit It accompanies a very small error because it works on commercial frequency 4 ACL Circuit A circuit to generate a signals which resets the LSI to the initial state when power is supplie...

Page 23: ...inet 5 Re connect the power supply cord after the outer case is installed 6 Run the oven and check all functions A On some models the power supply cord between the touch control panel and the oven itself is so short that the two can t be separated For those models check and repair all the controls sensor related ones included of the touch control panel while keeping it connected to the oven B On s...

Page 24: ...N PARTS CABINET PARTS DOOR PARTS when carrying out any of the following removal procedures BUILT IN FRAME ASSEMBLY REMOVAL To remove the built in frame assembly proceed as follows 1 Remove the four screws securing the frame assembly to the oven cavity two from the top and two from the hinge side 2 Remove the two screws securing the frame assembly to the control panel frame accessed from the back o...

Page 25: ...D CHECKS 2 Disconnect the H V wire B and filament lead of the transformer from the magnetron 3 Move the air intake duct to left 4 Carefully remove two 2 screws holding magnetron to the waveguide 5 Remove the magnetron from the waveguide with care so the magnetron antenna is not hit by any metal object around the antenna CAUTION WHEN REPLACING THE MAGNETRON BE SURE THE R F GASKET IS IN PLACE AND TH...

Page 26: ...nd rotating the fan blade with your hand 3 Now the fan blade will be free CAUTION Do not use this removed fan blade again Because the hole for shaft of it may become bigger than a standard one INSTALLATION 1 Install the fan blade to the fan motor shaft according to the following procedure 1 Hold the centre of the bracket which supports the shaft of the fan motor on a flat table 2 Install the fan b...

Page 27: ...y cord is free Re install 1 Insert the moulding cord stopper of power supply cord into the cut out of the N F U holder assembly referring to the Figure C 1 b Installation of Power supply cord 2 Install the earth wire lead of power supply cord to the N F U holder assembly with one 1 screw and tighten 3 Connect the brown and blue wire leads of power supply cord to the noise filter correctly referrin...

Page 28: ...rly and check continuity of the monitor circuit Refer to chapter Test Procedure and Adjustment Procedure below Figure C 2 Latch Switches Removal MONITORED LATCH SWITCH MONITOR SWITCH AND STOP SWITCH ADJUSTMENT 1 CARRY OUT 3D CHECKS If the monitored latch switch stop switch and monitor switch do not operate properly due to a misadjustment the following adjustment should be made 2 Loosen the one 1 s...

Page 29: ...le of upper and lower oven hinges 5 Re install choke cover to door panel by pushing Note After any service to the door A Make sure that monitored latch switch stop switch and monitor switch are operating properly Refer to chapter Test Procedures Switch Test page 17 B An approved microwave survey meter should be used to assure compliance with proper microwave radiation emission limitation standards...

Page 30: ...ts that comply with the requirement for instrumentations as prescribed by the performance standard for microwave ovens must be used for testing Recommended instruments are NARDA 8100 NARDA 8200 HOLADAY HI 1500 SIMPSON 380M 2 Place the oven tray into the oven cavity 3 Place the load of 275 15ml of water initially at 20 5 C in the center of the oven tray The water container should be a low form of 6...

Page 31: ...1 Disconnect the supply 2 Door opened and wedge open 3 Discharge the high voltage capacitor RE WIRING Ensure the following 1 Wires must not touch a High voltage parts Magnetron high voltage transformer high voltage capacitor and high voltage rectifier b Parts that become hot Heating elements oven lamp oven cavity magnetron and high voltage transformer c Sharp edges Bottom plates oven cavity wavegu...

Page 32: ... CUT OUT 125 C HIGH VOLTAGE TRANSFORMER CAPACITOR RECTIFIER MONITOR SWITCH MONITORED LATCH SWITCH STOP SWITCH OVEN LAMP FAN MOTOR TURNTABLE MOTOR TRANSFORMER T C NOISE SUPRESSION COIL NIOSE FILTER FUSE OVEN THERMAL CUT OUT 125 C MAGNETRON THERMAL CUT OUT 125 C HIGH VOLTAGE TRANSFORMER CAPACITOR RECTIFIER MONITOR SWITCH MONITORED LATCH SWITCH STOP SWITCH OVEN LAMP FAN MOTOR TURNTABLE MOTOR TRANSFOR...

Page 33: ...NITORED LATCH SWITCH MONITOR SWITCH STOP SWITCH MAG THERMAL CUTOUT OVEN THERMAL CUTOUT NOISE FILTER UNIT OVEN LAMP HIGH VOLTAGE COMPONENTS SHORT PROCTETOR HV CAPACITOR HV RECTIFIER POWER TRANSFORMER TURNTABLE MOTOR SWITCH UNIT LED BOARD MAINS SUPPLY CORD FAN MOTOR FA ...

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