Kuppersbusch EMWK 1050 User manual

Microwave oven
EMWK 1050
EMWG 1050

Service Manual: H4-79-01
Responsible: Dieter Rutz KÜPPERSBUSCH HAUSGERÄTE AG
E-mail: [e-mail]
Phone: [phone] Kundendienst
Fax: [phone] Postfach 100 132
Date: 21.06.07 45801 Gelsenkirchen

3 Service Manual
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Content
1. Safety...............................................................................................................................4
1.1 Microwave warnings..............................................................................................5
1.2 Electric connection ................................................................................................5
1.3 Converter switch warnings ....................................................................................5
2. Technical data and functions ........................................................................................6
2.1 Technical data and general information ...............................................................6
2.2 Microwave power levels ........................................................................................6
2.3 Ventilation system and air cycle ............................................................................7
2.4 Power levels and their applications .......................................................................7
2.5 Setting the clock ....................................................................................................8
2.6 Safety blocking ......................................................................................................8
2.7 Stopping the rotating plate.....................................................................................8
2.8 What cookware may be used in your appliance?..................................................9
3. Installation.....................................................................................................................10
3.1 Disposing of the packaging and your old appliance ............................................10
3.2 Before installation................................................................................................10
3.3 Installation ...........................................................................................................11
3.4 After the installation.............................................................................................12
4. Function tests ...............................................................................................................13
4.1 Safety precautions - microwave energy ..............................................................13
5. Cleaning.........................................................................................................................14
5.1 Cavity...................................................................................................................14
5.2 Surfaces ..............................................................................................................14
5.3 Grill ......................................................................................................................14
5.4 Turntable .............................................................................................................14
6. Accessing the individual components .......................................................................15
6.1 Turntable motor...................................................................................................16
6.2 Door, inner frame, hinges and closing device .....................................................16
6.3 Closing device and door alignment .....................................................................18
6.4 Control panel .......................................................................................................19
6.5 Ventilator .............................................................................................................20
6.6 Convection air......................................................................................................20
6.7 Grill ......................................................................................................................21
6.8 Replacing the light bulb .......................................................................................21
7. Safety precautions during troubleshooting...............................................................22
8. Leak test (leak indicator gauge)..................................................................................23
8.1 Abnormal operation (no-load operation)..............................................................23
8.2 Normal operation, loaded ....................................................................................23
9. Measuring the output power of the magnetron .........................................................24
10. Troubleshooting ...........................................................................................................25
10.1 General faults ......................................................................................................26
10.2 Internal faults.......................................................................................................28

Service Manual 4
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1. Safety
The purpose of this service manual is to provide the customer service technicians who already have the
technical knowledge necessary to repair microwave ovens with specific information on the mode of
operation of the EMWK / EMWG 1050.
Danger!
Repairs may only be carried out by a qualified electrician!
Incorrect repairs can be extremely dangerous for the user!
To prevent electric shocks, please observe the following tips:
• In the event of faults, housing and frame may be live!
• Touching live components inside the appliance may cause dangerous currents to flow through your
body!
• Unplug the appliance before repair!
• When inspecting live parts, a residual current operated device must be used at all times!
• The ground wire resistance must not exceed that specified in the standard! It is of vital importance for
ensuring the safety of people and the functioning of the appliance.
• On completion of repairs, an inspection must be carried out in accordance with VDE 0701 [Associa-
tion of German Electrical Engineers] or the corresponding regulations for your country!
• On completion of repairs, a function and impermeability inspection must be carried out.
• On completion of the repair work a leak rate measurement must be made!
Note!
It is essential to observe the following notes in order to prevent damage to the appliance or the
components:
• The appliances must be disconnected from the mains prior to all repairs. If inspections must be
carried out on live appliances, make sure you use a residual current operated device.
• Do not take any measurements in the high-voltage circuit during operation. Risk to life and
limb!
• The mains plug of the microwave oven must always be accessible!
• Do not replace any components as long as the appliance is functioning.
• When looking for faults proceed systematically as outlined in the fault-finding steps.
• Observe EGB instructions.
• Never attempt repairs through the indiscriminate exchange of components!
• Always proceed systematically and observe the notes on troubleshooting!
• Do not take any measurements in the high-voltage circuit during operation. Risk to life and limb!

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1.1 Microwave warnings
• The microwave oven generates high voltages which may lead to serious or even fatal injury -
it is essential to observe the safety regulations contained in this repair manual at all times.
• Always disconnect the microwave from the mains prior to removing or installing components. Never
attempt to measure voltage on the inverter, the magnetron or high-voltage conducting wire. This
high-voltage circuit generates voltages exceeding 4000 volts.
• Always connect the microwave oven to a residual current overload circuit breaker prior to measuring
electric currents.
• Check to ensure that the power required by the oven does not exceed the nominal power of the
mains power supply.
• Pull the plug out of the mains socket and discharge the high-voltage capacitors of the converter
switch prior to removing or installing components.
• Connect the microwave oven with a twin-wire extension cable. The microwave oven must be
earthed. Looking for faults on a microwave oven that is not earthed is extremely dangerous.
• Carry out a functional test when repair work has been completed.
• Carry out a microwave leakage current test when repair work has been completed.
1.2 Electric connection
• Only connect the appliance to sockets with a safety fuse of at least 16 A. Please also check to
ensure that the main fuse in your home has a minimum output of at least 16 A so that it will not sud-
denly trip when the microwave oven is in operation.
• Before operation, check whether the mains voltage is the same as that indicated on the name/rating
plate of the appliance and whether the socket outlet is effectively earthed. The manufacturer
assumes no liability for damage which occurs through the non-observance of these regula-
tions.
1.3 Converter switch warnings
• The converter switch generates current of more than 4000 volts! Never attempt to measure the volt-
age in this switch.
• The aluminium dissipater on the converter switch gets very hot! Allow the dissipator to cool down
prior to removing the converter switch.
• Pull the plug out of the mains socket and discharge the high-power capacitors of the conversion
switch before removing the converter switch.
• The converter switch must be earthed. After replacing the converter switch tighten the earth terminal
and the earthed leads to the microwave oven casing. A converter switch with no earth connection
may be dangerous.

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2. Technical data and functions
2.1 Technical data and general information
2.2 Microwave power levels
EMWG 1050
EMWK 1050
Voltage / Frequency 230V - 50Hz
Power consumption at 230 V 15A
Total electrical connection 3,3 kW (ready to plug in)
Microwave output 1000 W (max) (6 levels)
Grill levels EMWG 1050 1500 W
Appliance dimensions (WxHxD) 595 x 455 x 542 mm approx.
Niche dimensions (WxHxD) 560 x 450 x 550 mm
Cooking cavity dimensions (WxHxD) 420 x 210 x 390 mm approx. (capacity: 32 l )
Weight EMWK 1050.0 38 kg
EMWG 1050.0 32 kg
Program P00 P01 P02 P03 P04 P05
Power (W) 0 200 400 600 800 1000
Time ON (s) 0 6 12 18 24 30
Time OFF (s) 30 24 18 12 6 0
Program P00 P01 P02 P03 P04 P05
Power (W) 0 200 400 600 800 1000
Time ON (s) 0 6 12 18 24 30
Time OFF (s) 30 24 18 12 6 0

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2.3 Ventilation system and air cycle
Air circulation
Surplus hot air in the interior flows through the holes in the rear wall.
A second flow of air flows through the air channel under the fastening clamp.
Both air currents flow through the outlet on the left and right at the front of the interior cavity.
Ventilation system
Fresh air flows from below and from the back into the housing. The cross flow fan ensures that the elec-
trical components on the fastening clamp are cooled. Hot air is lead to the outside through the air chan-
nel. An air valve controls the supply of air during operation as follows:
• MW and MW+GRILL:
Air valve up, some air is supplied through the openings in the interior and also between the doorand
the control panel.
• Combined mode:
Air valve down for enclosing the air in the interior. The air circulates between the door and the control
panel.
2.4 Power levels and their applications
In order to ensure maximum possible flexibility during the cooking process, the microwave oven was
equipped with different power levels:
1000 W Very rapid heating of liquids and (fresh or deep-frozen) food and for cooking vegetables
800 W For cooking fish and poultry in general
600 W For melting chocolate and chocolate coatings and for cooking meat in general
(roasts, meat kebabs etc.)
400 W For very slow cooking, e.g. braising joints, and for heating cakes and pastries.
200 W For baking certain types of cake and for sensitive foods (fish, roast beef etc.)
For defrosting according to weight or time

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2.5 Setting the clock
After your microwave oven is first plugged in orafter apowerfailure, the clock display willflash toindicate
that the time shown is not correct. To set the clock, proceed as follows:
1. Press the Clock key. The hour numbers will start to
flash.
2. Press key “-” and “+” to set the hours.
3. Press the Clock key to set the minutes. The minute
numbers will start to flash.
4. Press key “-” and “+” to set the minutes.
5. To finish, press the Clock key again.
Hiding/Displaying the Clock
If the clock display bothers you, you can hide it by pressing the Clock key for 3 seconds. The dots that
separate the hours and minutes will flash but the rest of the clock display will be hidden. If you want to
see the clock display again, press the Clock key again for 3 seconds.
2.6 Safety blocking
The oven functioning can be blocked (for example, to stop it being used by children).
1. To block the oven, press the Stop key for 3
seconds. You will hear a sound signal and the dis-
play will show the word “SAFE”. The oven is blok-
ked in this state and cannot be used.
2. To unblock the oven, press the Stop key again for 3
seconds. You will hear a sound signal and the display will show the time again.
2.7 Stopping the rotating plate
1. To stop the rotating plate, press the "+" key and the
Stop key at the same time
2. To start plate rotation again, press the "+" key and
the Stop key at the same again.

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2.8 What cookware may be used in your appliance?
In the mode “only microwaves” and in the combination modes with microwaves all containers made of
glass (Pyrex even better), ceramic, porcelain or terracotta may be used as long as they have no
decorations and metal parts (decorative or gold edges, handles, feet). Heat-resistant plastic containers
(200 °C) may also be used.
Containers made of metal, wood, straw and crystal are unsuitable for cooking with microwaves.
At this point you should be reminded once again that the microwaves heat the food and not the cook-
ware and therefore the meals can be cooked directly in the serving dishes; this dispenses with the use
and subsequent washing-up of pots and pans. However, it is possible for the very hot food to transfer its
heat to the plate, thus necessitating the use of oven cloths.
If the appliance is set at the modes “Only hot air oven” or “Only grill”, all containers suitable for a stan-
dard oven may be used.
However, their shape and size must always permit the turntable to rotate properly.
To find out whether a container is suitable for a microwave oven, please conduct the following
small test:
Place an empty container in the oven for 30 seconds at the maximum power level (function “Only mic-
rowaves”). If the container does not become warm at all or becomes only slightly warm, it is suitable for
cooking with microwaves. If, on the other hand, it heats up a lot (or sparks develop), it is unsuitable.
Mode Only microwaves Combination mode Only hot air / grill
Glass YES NO NO
Pyrex YES YES YES
Glass ceramic YES YES YES
Terracotta dishes YES YES YES
Aluminium foil NO NO YES
Plastic YES NO NO
Paper or cardboard YES NO NO
Metal containers NO NO YES

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3. Installation
3.1 Disposing of the packaging and your old appliance
The packaging material for transport is fully recyclable.Recycling the packaging saves raw materials and
reduces the amount of waste.Disposed appliances still contain useful materials. Take your old appliance
to a recycling collection point. Please make your old appliances unserviceable before disposing of it, to
prevent it from misuse.
3.2 Before installation
• Check that the input voltage indicated on the characteristics plate is the same as the voltage of the
power outlet you are going to use.
• Open the oven door and take out all the accessories and remove the packing material.
• Do not remove the mica cover on the ceiling of the interior! This cover prevents fat and pieces of food
from damaging the microwave generator.
•Warning! The front surface of the oven may be wrapped with a protective film. Before using the oven
for the first time, carefully remove this film, starting on the inside.
• Make sure that the oven is not damaged in any way. Check that the oven door closes correctly and
that the interior of the door and the front of the oven opening are not damaged.
• Put the oven on a flat and stable surface. The oven must not be put close to any heat sources, radios
or televisions. During installation, make sure that the power cable does not come into contact with
any moisture or objects with sharp edges behind the oven. High temperatures can damage the
cable.
Warning!
After the oven is installed you must make sure you can access the plug.

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3.3 Installation
1. Open the packaging and remove the
appliance.
2. Do not lift up the microwave by the
door handle since this may damage
the inner frame of the door.
3. Remove the adhesive tape from the
door and carefully install the micro-
wave in the niche.
4. Fasten the microwave on the inside
of the frame.
The appliance needs an adequate air
supply. The opening on the strip must
hence be at least 100 mm wide.

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3.4 After the installation
• If the oven is to be installed on a permanent basis it should be installed by a qualified technician. In
such a case, the oven should be connected to a circuit with an all-pole circuit breaker with a mini-
mum separation of 3 mm between contacts.
• Only connect the appliance to sockets with a safety delay fuse of at least 16 A. Please also check to
ensure that the main fuse in your home has a minimum output of at least 16 A so that it will not
suddenly trip when the microwave oven is in operation.
WARNING! THE OVEN MUST BE EARTHED.
• The manufacturer and retailers do not accept responsibility for any damage that may be caused to
people, animals or property if these installation instructions are not observed.
• The oven only functions when the door is closed correctly. After the first use, clean the inside of the
oven and the accessories, following the cleaning instructions given in the section “Oven cleaning and
maintenance”.
• Fit the turntable support (1) in the centre of the oven cavity and put
the turntable ring (2) and the turntable plate (3) on top, making sure
they slot in. Whenever you use the microwave, the turntable plate
and the respective accessories must be inside and correctly fitted.
The turntable plate can rotate in both directions.

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4. Function tests
4.1 Safety precautions - microwave energy
Service technicians must never be exposed to the microwave radiation which can be
emitted by the magnetron or other components producing microwaves if the appliance
is not connected correctly or operated improperly.
All input and output connections, waveguides, flanges and seals are to be attached and
sealed correctly.
Never operate the appliance without having placed items in the cooking cavity which
absorb the microwaves.
Never look into the open waveguide or the antenna when the. magnetron is live.
The appliance must never be operated without the housing or with the door open.
If the fuse blows, always block the system operability first (all microswitches) before the
appliance is switched on again. If a microswitch is defective, always replace all micro-
switches.
Before activation of the magnetron or before repair work, check the following points with all
appliances:
• The door does not close properly at the frame because it is deformed or the hinges are damaged.
• Door or door seal damaged.
• Appliance obviously damaged.
All defective or incorrectly set components in the locking, control, door locking,microwave generator and
transmission systems must be repaired, replaced or correctly set. Service technicians must first remove
their watches for all work on or near the magnetron.
•Attention!
The high-voltage capacitor could still be electrically charged about 30 sec. after the appliance has
been switched off. It is advisable to discharge the capacitor each time through both poles using a
suitably insulated cable. Secondary power circuits of the transformer have a high voltage and a low
amperage and for this reason it is extremely dangerous to work near these components if the
appliance is plugged into the mains. Never touch cables with your bare hands or with non-insulated
tools when the appliance is in operation.
• Do not measure the electric voltage of a high-voltage circuit or magnetron filament.
• Make sure that the door is not loose or missing. If the screws are not properly tightened, this could
lead to the discharge of microwaves.
• Before you switch on the appliance, check that all electric connections are tight.
• Ensure with a reasonable procedure that no microwaves are emitted.
• Do not insert any metal objects through the lamp gap or through any other gap as such objects could
act as an antenna and could result in the emission of microwaves.

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5. Cleaning
Prior to all maintenance or cleaning work always pull out the mains plug and wait until the
appliance has cooled down.
5.1 Cavity
The cavity is made of stainless steel and therefore cleaning is extremely easy. Always keep the cover
panel of the microwave outlet opening free of oil and grease splashes.
5.2 Surfaces
Never use scouring agents, metal wool or sharp metal objects for cleaning the surfaces. Moreover, make
sure that no water or liquid cleaning agent enters the waste air and vapour extractor slits on the top of
the appliance. No alcohol, scouring agents or ammonia-containing cleaning agents are to be used for
cleaning the inside and outside of the door. To ensure perfect closing, always keep the inside of the door
clean and make sure that dirt and food residues are not jammed between the door and the appliance
front.
5.3 Grill
If the oven ceiling is dirty, the grill can be lowered to make cleaning easier. To avoid the danger of bur-
ning, wait until the grill is cold before lowering it. Proceed as follows:
1. Turn the grill support by 90º.
2. Lower the grill gently (2). Do not use excessive force as this may
cause damage.
3. The mica cover (3) located in the ceiling must always be kept clean.
Any food remains that collect on the mica cover can cause damage
or provoke sparks. Do not use abrasive cleaning products or sharp
objects. To avoid any risk, do not remove the mica cover.
Caution! After cleaning, correctly position the grill heating
element again and hook it on. The combination
microwave oven must not be operated with the grill heating element flapped
down. Never operate the microwave oven without a mica cover!
4. After cleaning the ceiling re-position the grill (2) by proceeding in reverse order.
5.4 Turntable
The turntable and the corresponding holder should also be removed for cleaning and the bottom of the
microwave oven cleaned from time to time.
Clean the turntable and the holder with normal washing-up liquid (they are also dishwasher-safe).
Do not immerse the turntable after prolonged heating in cold water; it would break owing to the severe
temperature shock.

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6. Accessing the individual components
Open the top casing to access:
• High-voltage circuit
• Electronic controls
• Grill
• Wiring
• Cross flow fan
• RFI filter
Remove the lower B1 air channel to access:
• Thermostat 90º+150º C
• Thermal cut-off device
• Halogen lamp transformer
• Electromagnetic activator
• Air valve lever
Remove the back casing to access:
• Fan motor (only wiring and heating)
• Thermostat 150 ºC
Remove the turbo chamber to access:
• Recirculating air heater
• Motor and fan
Remove the side panels to access:
•Catch
• Hinged fastenings
Remove the fastening bracket to access:
• Halogen lamp holder

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6.1 Turntable motor
1. Remove the attachments.
2. Close the door and lie the microwave down on the
back.
3. Remove the motor cover.
Pay close attention to the silicone sealing and the
insulation panel of the grill (for combination models only).
Caution! The motor of the turntable must have a
metal shaft!
6.2 Door, inner frame, hinges and closing device
In order to be able to re-use individual elements without any damage we have below listed the correct
procedure for removing the door and its components. The inner frame is only pressed on without the
help of any devices such as screws or pins.
Removing the door
1. Pull the door right open.
2. Insert rivets into the holes of the hinge.
3. Pull the door upwards out of the hinges.
Removing the inner frame
1. Lift up the frame direct next to the hinges and remove
it. The frame is a little thinner at this point and can be
lifted out more easily.

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2. Firstly use a screwdriver to carefully lift out the
frame on the outside between the two hinges
direct next to the glass.
3. Repeat this procedure on the left side.
4. Remove the inner clips on both sides of the
frame.
5. Finally carefully remove the silicon sealing.
Re-assembling the inner frame
1. Insert the hob seal all around, without any gaps. Begin in the centre of the underside of the new
frame. The beginning and the end must meet. Make sure that the seal is not deformed.
2. Put the frame into the hinges and align it with the door.
3. Now begin pressing the frame on the underside
and check to ensure that the inner profiles on the
door are properly fitted (2 elements). Make sure
that the clips are in the proper mounting position.
4. Now press the left side and check here too to
ensure that the profiles and the clips have been
properly fitted.
5. Repeat these steps on the other two sides.
6. Now press around the inner edges and make sure
that the clips are correctly positioned.
7. Check all around the outer frame. It must be fully inserted and must touch the glass surface.
Re-assembling the door and the closing device
1. Remove the rivets and suspend the hinges in the holders.
2. Close the door and check the respective positions with the control panel.
3. Align the door and the hinges again if necessary.
4. Check to ensure that the micro-switches are working properly and that the door closes smoothly.
Attention!
It is very easy to remove the door, but the inner frame may break while you are
doing so. To avoid having to replace the whole door, the frame is available under
spare-part no. 528949.

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6.3 Closing device and door alignment
Closing device
Two essential items need to be observed to enable the closing device to function properly.
1. The position of the box for the closing device (right and
left): this box must be mounted securely in the fastening
clips and must be installed flush with the front edge of the
oven (right-hand box: spare part no. 528925, left-hand box:
spare part. no. 528926).
2. The shape of the original black box was modified so that
the box fitted better. In order to distinguish between the
boxes, the new box is now available in white under the
same spare-part number.
Please note!
Now and then the problem may occur with the
newly-designed holders too, when the appliance
has been used frequently or when it has been used
for grilling for a longer period. Expansion of the
metal cover causes it to press the switch holder out
of its position. In this case the underside of the
holder, which makes contact with the oven cover,
will need to be sandpapered or cut to shorten it by
about 2 mm.
down
front
about 2 mm

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Door alignment
The door must be parallel and flush with the
control panel. The clearance between the door
and the control panel must be approx. 7 mm.
In order to avoid alignment problems as a result of
transporting the appliance, the door is fastened to
the casing with adhesive tape to protect the
appliance from strong vibrations.
The door can also be aligned when it has been
mounted. The hinged door holder (spare-part no.
528895) must be released in order to relieve the
door tension. The door will then need to be adjus-
ted so that the clearance between the door and
the control panel is 7 mm. The screws are then
tightened again.
6.4 Control panel
1. Remove the four fastening screws.
2. Loosen the four clips on the lower edge first and then those on the top edge.
3. Now carefully pull out the control panel, paying close attention to the cables and the electronic
components.
Caution! Be particularly careful with the inner frame after the control panel has been
removed, since it may break.
7 mm
hinged door holder
Screws

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6.5 Ventilator
Remove the casing at the back in order to access the motor. The pre-chamber must be completely
removed before the ventilator can be replaced.
1. Remove the nut so that the coil spring can move freely.
2. Turn the motor anti-clockwise to release it.
6.6 Convection air
1. Remove the complete pre-chamber.
2. Remove the nuts in order to loosen it.
3. When replacing the chamber, pay attention to the pre-
chamber in the interior to make sure that it is properly
connected to the back fastenings. Only screw the pre-
chamber tight after it has been properly aligned.
Screws Screws
Clips