Bosch HMC54151UC/01 User manual

SERVICE MANUAL
for
Speed Microwave Ovens
HMC54151UC
This manual contains information that is necessary for
servicing the following Bosch Speed Microwave Ovens:
HMC54151UC
This manual is designed to be used by qualified service
personnel only. Due to the complexity and the risk of
high-voltage electrical shock, Bosch does not
recommend that customers service their own units.
This material is intended for the sole use of BSH
authorized persons and may contain confidential and
proprietary information. Any unauthorized review, use,
copying, disclosure, or distribution in any format is
prohibited.

REPAIR INSTRUCTION
1SAFETY·································································2
1.1 Danger ·················································································2
1.2 Caution!················································································2
1.3 Leak test (leak detection measurement) ·······························3
COMPONENTS···················································4
High-voltage diode ·····························································4
High-voltage capacitor························································5
High-voltage transformer ····················································6
Magnetron··········································································7
Safety switches ··································································8
REPAIR ·······························································9
Removing the door ·····························································9
Removing the bottom heating system ································ 10
Removing the turntable motor ············································ 11
Removing the cooling fan··················································· 12
Removing the upper heating elements ······························· 13
Removing the hot air motor ················································ 14
Removing the magnetron ··················································· 15
FAULT DIAGNOSTICS······································· 16
Troubleshooting plan - fuse is tripping································ 16
Troubleshooting plan - appliance does not function at all ··· 17
Troubleshooting plan - appliance does not start ················· 18
Troubleshooting plan - no microwave power ······················ 19
Troubleshooting plan - input module ·································· 20
Troubleshooting plan - Error Codes of input module. ········· 22
Determining the microwave output power··························· 23
Page 1 of 23 pages
2
2.1
2.2
2.3
2.4
2.5
3
3.1
3.2
3.3
3.4
3.5
3.6
3.7
4
4.1
4.2
4.3
4.4
4.5
4.6
4.7
This material is intended for the sole use of BSH authorized persons and may contain confidential and proprietary information. Any unauthorized review, use, copying, disclosure, or distribution in any format is prohibited.
______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

1 SAFETY
1.1 Danger
Repairs may be carried out by an electrician only!
Improper repairs may endanger and injure the user!
To prevent electric shocks, always comply with the following
information:
• If the appliance is faulty, the housing and frame may be live!
• Do not touch any modules in the appliance, even modules can be
live!
• Before commencing repairs, always disconnect the appliance from
the power supply!
• If tests have to be performed while the appliance is live, always
use a residual-current-operated circuit-breaker!
• The protective conductor connection must not exceed the standard
values! This connection is extremely important for personal safety
and function of the appliance!
• When repairs are complete, conduct a test in accordance with
VDE 0701 or national regulations!
• When repairs are complete, conduct a function test!
• When repairs are complete, conduct a leak rate test!
1.2 Caution!
Always comply with the following instructions to prevent damage to
the appliance or to components:
• Comply with ESD instructions!
• Never attempt repairs by randomly replacing components!
• Always proceed systematically and follow the troubleshooting
instructions!
• Do not test the high-voltage circuit while the appliance is running –
Danger of death -!
• Always discharge the high-voltage capacitor before testing!
Page 2 of 23 pages
This material is intended for the sole use of BSH authorized persons and may contain confidential and proprietary information. Any unauthorized review, use, copying, disclosure, or distribution in any format is prohibited.
______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

1.3 Leak test (leak detection measurement)1.3 Leak test (leak detection measurement)
The leak rate is the microwave energy which escapes despite the
intact sealing systems.
The leak rate is the microwave energy which escapes despite the
intact sealing systems.
The leak rate is measured as an energy density with suitable
measuring instruments at a distance of 5 cm. The unit of
measurement is mW/cm2.
The leak rate is measured as an energy density with suitable
measuring instruments at a distance of 5 cm. The unit of
measurement is mW/cm
The limiting values for the permitted measured values, as well as
the measurement conditions, have been specified in the VDE
regulation 0700/Part 25 and are as follows:
The limiting values for the permitted measured values, as well as
the measurement conditions, have been specified in the VDE
regulation 0700/Part 25 and are as follows:
1.3.1 Normal operation with load1.3.1 Normal operation with load
Setting: maximum power setting of the applianceSetting: maximum power setting of the appliance
Load: 275 cm3waterLoad: 275 cm
Permitted limiting value: 5 mW/cm2Permitted limiting value: 5 mW/cm
Measurement distance: 5 cmMeasurement distance: 5 cm
2.
3water
2
1.3.2 Abnormal operation (no-load operation)
Setting: maximum power setting of the appliance
Load: none (no-load operation)
Permitted limiting value: 10 mW/cm2
Measurement distance: 5 cm
Page 3 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

Set to insulation resistance.
2 COMPONENTS
2.1 High-voltage diode
Blocking direction = infinite.
The high-voltage diode can be tested like a standard diode.
Use an EHG tester for this.
• Full continuity in conducting direction.
• Infinite in blocking direction.
Set to insulation resistance.
Conducting direction = full continuity.
Page 4 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

2.2 High-voltage capacitor
The high-voltage capacitor can be tested by ‘ohmic’ measurement’
(resistance measurement range 20 ΜΩ).
A correctly functioning capacitor indicates transient continuity.
The resistance then increases proportionally with the load.
A defective capacitor (e.g. short-circuit) indicates permanent
continuity.
The measuring instrument must indicate infinitely between the
connection and housing.
Page 5 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

2.3 High-voltage transformer
This transformer supplies the heater voltage for the magnetron and
the operating voltage for doubling the voltage.
• Input voltage 230 V
• Heater voltage approx. 3.3 V
• Operating voltage approx. 2300 V
The operating voltage cannot be measured!!
Heater voltage of
approx. 3.3V
Primary side 230V
of input voltage
Page 6 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

2.4 Magnetron
The magnetron can be tested by ‘ohmic’ measurement´ only.
The volume resistance of the terminals F and FA should be less than 1
Ω.
The insulation resistance between the two terminals and the housing
should be infinite.
Measure the resistance with an EHG tester.
Note:
An internal flashover (short-circuit between cathode and anode)
cannot usually be established by taking a measurement.
This is not indicated until the appliance is switched on when high
voltage is applied to the magnetron.
It may also be possible to detect the fault by loud humming noises.
Before installing the magnetron, ensure that the metal seal is ok and is
seated correctly.
Page 7 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

4.5.1 Switching sequence
2.5 Safety switches
Each door switch independently switches off the power supply for the
microwave oven when the door is opened.
Microwave ovens usually feature at least three safety switches.
The switching sequence is specified by the arrangement and is as
follows.
These switches are supported by the switch brackets.
The basic function of these switches is to interrupt microwave
generation as soon as the door is opened.
One of the three switches is the short-circuit switch. It monitors one of
the two other switches and actuates the appliance safety device if the
monitored switch does not function.
Switching
sequence
Open door Close door
1.) Safety switch on right Short-circuit switch
2.) Safety switch on left Safety switch on left
3.) Short-circuit switch Safety switch on right
In this case the appliance is disconnected from the power supply and
can no longer be switched on.
Page 8 of 23 pages
This material is intended for the sole use of BSH authorized persons and may contain confidential and proprietary information. Any unauthorized review, use, copying, disclosure, or distribution in any format is prohibited.
______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

3 REPAIR
3.1 Removing the door
1. Open the door and insert the "HOLDERS" into the recesses in front
of the hinges.
2. Carefully close the door and lift out of the hinge thrust bearings.
NOTE:
After re-installing the door, ensure that the safety switches function
normally.
Page 9 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

3.2 Removing the bottom heating system
1. Remove the housing.
2. Discharge the HV capacitor.
3. Take the turntable out of the appliance.
4. Disconnect the heating system.
5. Unscrew the heating system on the bottom and right.
6. Slide the heating system to the right and then lift out of the
appliance.
Page 10 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

3.3 Removing the turntable motor
1. Take the metal plate out of the appliance.
2. VERY CAREFULLY prise out the turntable shaft with a flat
screwdriver.
3. Place the appliance on its back.
4. Remove the cover from the turntable motor.
This cover has been punched into the base plate. It can easily be
removed with side cutters.
5. Disconnect the turntable motor.
6. Remove the screws which attach the turntable motor to the cooking
compartment.
7. After repairing or replacing the motor, screw the cover to the base
plate with a screw.
Page 11 of 23 pages
This material is intended for the sole use of BSH authorized persons and may contain confidential and proprietary information. Any unauthorized review, use, copying, disclosure, or distribution in any format is prohibited.
______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

3.4 Removing the cooling fan
1. Remove the housing.
2. Discharge the HV capacitor.
3. Unscrew the H.V. diode.
4. Disconnect the magnetron.
5. Disconnect the fan motor.
6. Unscrew and remove the cooling fan assembly.
7. Unscrew the fan retaining plate and remove in the direction of the
structure.
Page 12 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

3.5 Removing the upper heating elements
1. Remove the housing.
2. Discharge the HV capacitor.
3. Unscrew the cooling fan assembly, and lift out.
4. Disconnect the magnetron and the H.V. transformer.
5. Unscrew and remove magnetron and H.V. transformer.
6. Disconnect the wiring above the upper heat protector assembly.
7. Unscrew the upper heat protector assembly from the cavity upper
plate, and lift out carefully.
7. Disconnect the heating elements.
8. Remove the hex nuts on the right side of cavity and on the upper of
cavity.
9. Lift out the upper heating elements from the cavity.
Page 13 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

3.6 Removing the hot air motor
1. Remove the housing.
2. Discharge the HV capacitor.
3. Remove the rear cover.
4. Disconnect the Hot air assembly.
5. Remove oven sensor.
6. Unscrew the Hot air assembly and lift out carefully.
7. Disconnect the Hot air motor.
8. Remove the hex nut which attaches the inner fan blade to the shaft
of the hot air motor.
9. Pull out the inner fan blade in the hot air chamber.
10. Unscrew the hot air motor bracket.
11. Lift out the hot air motor with the bracket, and remove the outer fan
blade.
12. Unscrew the hot air fan motor from the hot air motor bracket.
Page 14 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

Removing the magnetron3.7
1. Remove the housing.
2. Discharge the HV capacitor.
3. Remove the magnetron TCO.
4. Disconnect the magnetron.
5. Remove the left air guide.
6. Unscrew the magnetron.
NOTE:
When re-installing the magnetron, ensure that the fastening screws
are tightened to prevent microwave energy from escaping. Also
ensure that there is no gap between the hollow conductor and
magnetron.
Page 15 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

FAULT DIAGNOSTICS4
4.1 Troubleshooting plan - fuse is tripping
The appliance does not function at all; there are no symbols/numerals on the display and no inputs are accepted.
Page 16 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

4.2 Troubleshooting plan - appliance does not function at all
Page 17 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

4.3 Troubleshooting plan - appliance does not start
Page 18 of 23 pages
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______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091

4.4 Troubleshooting plan - no microwave power
Page 19 of 23 pages
This material is intended for the sole use of BSH authorized persons and may contain confidential and proprietary information. Any unauthorized review, use, copying, disclosure, or distribution in any format is prohibited.
______________________________________________________________________________________________________________________________________________________________________________
Copyright by BSH Home Appliances Corporation 1901 Main Street, Suite 600, Irvine CA 92614 700_ 58300000192890_ARA_EN_A 800 444-9091