Electrolux In General, Service Manual

Page 1: ... 135 D 90429 Nürnberg Germany Fax 49 0 911 323 1420 TSE N Publ Nr 599 510 968 03 2001 MICROWAVE OVENS IN GENERAL Trainingsunterlagen EN Ausgabe Microwave Ovens in general Fundamentals Measuring technique Fault finding created by TSE N Reiner Kurzke Page 1 ...

Page 2: ...19 Measurements in practice 20 Voltage measurement Easy Way Measurement of capacity levels 21 Rules for leaky rays Measurement of leaky rays 22 Checking of the interlock door safety system Measuring the fuse diode Checking the high voltage diode 23 Measuring the magnetron Measuring the high voltage capacitor Checking the high voltage transformer 24 Fault finding trees 25 Fault finding tree 26 Faul...

Page 3: ...ectrum time saving cooking speed the taste natural flower healthy cooking no fat used no loss of vitamins energy saving no pre heating time saving speed quick and problem free defrosting less washing up foot cooked in the serving dish easy to clean easy to use Frequency Microwaves are in the nonionizing range They therefore also do not have anything to do with radioactivity Radioactivity can only ...

Page 4: ...arks or when the waves have a retrospective effect on the magnetron to a damaging of its anode Therefore never use an empty microwave oven Interpenetration Many materials let microwaves pass through without that they react themselves glass porcelain pottery plastic suitable for microwaves and paper board dry This is used during the microwave operation The waves can penetrate into the food without ...

Page 5: ... BE USED IN THE MICROWAVE OVEN Suitable Ovenware O suitable non suitable 1 excluding silver gold platinum or metal decoration 2 does not include glaze containing metal 3 please note the maximum temperature stated by the manufacturer created by TSE N Reiner Kurzke Page 5 ...

Page 6: ...soups should be stirred for a change for the same reason This helps to distribute the heat and prevents too high temperatures on the surface In the extreme case this could attack the upper edge of the material when using plastic containers In any food positively negatively charged liquid molecules are accidentally arranged in disorder If we now put this food into an electromagnetic field these mol...

Page 7: ...r flow of the fan is partly used in order to operate the wave agitator by it Various ways of feeding and distribution of microwaves Using turntables guarantees a good distribution of waves for the food Guiding of Waves Oven with stirrer 1 Bottom Plate 2 Housing 3 Cooking Area 4 Sheet 5 Stirrer 6 Microwave Input 7 Duct 8 Anode 9 Magnetron 10 Ventilator 11 High Voltage Transformer Oven without stirr...

Page 8: ... 15 seconds ON and 15 seconds OFF The timing cycles can differ a little bit due to the different types electronic timer the principle is always the same Thus 10 of these cycles will pass within 5 min Following important note Never switch on a microwave oven without energy absorbingfoodintheoven Ifdespite that microwave energy is fed to an empty oven these waves work off their energy where it is no...

Page 9: ...nic with a display Instead of a controller it is also possible to use input fields Hereisatypicalportray of the control panel from an instruction manual Just with appliances controlled by electro nics you can find the most different equip ment features and pro grammes The basic function of the microwave oven is on the whole always the same Input Control Panels created by TSE N Reiner Kurzke Page 9...

Page 10: ...n the microwave oven In this connection one has to observe that the microwave energy only affects the food from above and that the required cooking duration will thereby be extended Furthermore a distance of 2 cm to the oven wall must be kept to in order to avoid a sparkover Aluminium foil wrapped around thinner parts such as ends of poultry legs shields the microwave energy and thus prevents a to...

Page 11: ...Wiring diagram of a timer controlled microwave oven The various sections are explained on the following pages created by TSE N Reiner Kurzke Page 11 ...

Page 12: ...ening the door all 3 microswitches are actuated via at least two mechanical systems In doing so primary and secondary switches interrupt the power supply If for whatever reason one of these switches does not open the monitoring switch short circuits the entry circuit resp high voltage transformer The triggering off of the fuse is hereby accepted Safety first Mechanical safety system primary second...

Page 13: ...interlock safety system can have a different view from one model to the other when looking first at the wiring diagram The basic functions are always the same Interlock Safety System created by TSE N Reiner Kurzke Page 13 ...

Page 14: ...ing with each other see under Electr safety system More elements such as the overheat thermostat for the magnetron can be installed depending on the model thermostat of oven grilling or air duct The suppressor filter is blocking high frequencies and demanded by law The function of the secondary and or high voltage circuit is explained on the following pages Primary Circuit Secondary Circuit create...

Page 15: ...arts are indispensable for the prevention of vibrations to the casing If the primary winding is supplied with a mains voltage of 230 V following voltages are induced into secondary windings 3 1 V as low voltage directly connected with the heating winding of the magnetron for heating the cathodes 2 750 V as high voltage connected with the voltage doubling High Voltage Transformator created by TSE N...

Page 16: ...voltage of the secondary winding of the high voltage transformer are converted into over 4 000 Volt DC voltage That operates the magnetron After the oven has been switched on the first positive wave charges the capacitor with more than 2 000 Volt After the polarity has been changed the diode avoids that the capacitor is discharging The voltage of the positive half wave is added to the charge of th...

Page 17: ...AK Diode created by TSE N Reiner Kurzke Page 17 ...

Page 18: ...uter cylinder The magnetron requires a high DC voltage 4 000 Volt a low AC voltage for the heating of cathodes and a magnetic field to be able to work The cathode is heated in order to cause the electrons emitting so that they will flow to the anode In order to achieve the oscillation one needs a permanent magnet Because of its magnetic field the electrons are moving in an orbit round the cathode ...

Page 19: ...s from the outside In case of measurements or repairs PULL THE MAINS PLUG By all means discharge the high voltage capacitor before This must be made by suitable lines with isolated peaks With every microwave oven it is necessary to carry out a high frequency leakage check measurement of leaky rays and the checking according to VDE 0701 after a repair the mere opening of the oven is also a repair M...

Page 20: ...50 off 50 capacity 30 on 70 off 30 capacity Useful clock cycle 30 seconds 1 liter water 17 24 62 seconds full capacity Measurement of capacity simple version Important Use a container with thin material Thick container walls extract parts from the water of the rising heat and falsify the measuring result If possible initial temperature 20 C Exact time measurement An exact thermometer if possible a...

Page 21: ...it in the middle of the oven Close door Timer to 3 minutes Capacity to 100 Start oven For use of the measuring device see its operational manual Check the leaky rays by moving the test probe from right above clockwise starting at the door not faster than 25 mm sec back to the initial position The measurement must be made in a distance of 5 cm Styrofoam distance pieces or other distance pieces are ...

Page 22: ...s Disconnect the mains plug before any measurement Short circuit the capacitor with suitable isolated means and thus discharge it Check the fuse diode in both directions for passage An intact fuse diode must LOCK in both directions Unplug the oven from the mains Ensure that the capacitor is discharged Disconnect the diode for measurement Measure in both directions using an ohmmeter with the highes...

Page 23: ...f the casing must be infinite Measuring the high voltage capacitor Small resistance increasing fast ok Small resistance remaining short circuit Very high resistance remaining interruption In the case of a capacitor exchange please use by all means the original capacitor The correct function and the values depend to a great extent on the exact capacity Measuring the magnetron Checking the high volt...

Page 24: ...r controlled microwave ovens Mains voltage existing timer in function door closed Fault finding tree of timer controlled microwave ovens Mains voltage existing timer in function door closed created by TSE N Reiner Kurzke Page 24 ...

Page 25: ...Fault finding tree of timer controlled microwave ovens Mains voltage existing timer in function door closed created by TSE N Reiner Kurzke Page 25 ...

Page 26: ...Fault finding tree for microwave ovens No microwave capacity fan is running created by TSE N Reiner Kurzke Page 26 ...

Page 27: ...Fault finding tree for microwave ovens No function no reaction to any entry created by TSE N Reiner Kurzke Page 27 ...

Page 28: ...ou have to stick to a distance of 2 cm to the oven wall that no sparks will jump over As these meals get cooked very fast a lot of steam will arise When the meals are covered only loose nothing will fall down in the oven The heat within covered meals is spreading better Covered meals do not dry up so fast When an over baking is intended the food should not be covered When using the grilling functi...

Page 29: ...ss cooking of food rather less 600 W defrosting and heating of frozen foods heating of one pot courses 500 W finish cooking of hot pots cooking of egg dishes 450 W continued cooking of meals 350 W cooking of sensitive food heating of baby food 250 W swelling up of rice melting of gelatine 150 W defrosting of meat fish bread 80 W defrosting of cheese cream butter raise the yeast dough preheating of...