Samsung SMH8165B/XAC, Service Manual

Page: 25 / 50

5
4. Troubleshooting
Timer starts countdown but no microwave oscillation .
(No heat while oven lamp and fan motor turn on.)
Fuse is OK
Open or loose lead wire harness
Open thermal cutout (Magnetron)
Open low voltage transformer
Check fan motor when thermal cutout is defective.
Check Ass’y PCB when L.V.T is defective.
Check adjustment of primary, interlock monitor,
power relay, door sensing switch.
NOTE 1 : All of these switches must be replaced at the same time. (refer to adjustment instructions)
Check continuity of power relay contacts and if it has continuity, replace power relay also.
NOTE: Large contact resistance will bring lower magnetron filament voltage and cause magnetron
to lower output and/or intermittent oscillation.
NOTE 2 : When H.V.Transformer is replaced, check diode and magnetron also.
Defective Ass’y PCB
Shorted lead wire harness
Defective primary latch switch
(NOTE 1)
Defective monitor switch
(NOTE 1)
Shorted H.V.Capacitor
Shorted H.V.Transformer
(NOTE 2)
Oven does not
accept key input
Key input is not in-Sequence
Open or loose connection of
membrane key pad to Ass’y PCB
Shorted or open membrane panel
Refer to operation procedure.
Replace PCB main.
Defective Ass’y PCB
Timer starts
countdown but
no microwave
oscillation
Off-alignment of latch switches
Open or loose connection of high
voltage circuit especially magnetron
filament circuit
(NOTE)
Defective high voltage components
H.V.Transformer H.V. Capacitor
H.V.Diode, H.V.Fuse Magnetron
Adjust door and latch switches.
Check high voltage component according to
component test procedure and replace if it is
defective.
Open or loose wiring of power relay
Replace PCB main.
Defective primary latch switch
Defective power relay or Ass’y PCB
Oven can program but timer does not start .
Oven can program
but timer does
not start
Open or loose wiring of secondary
interlock switch
Adjust door and interlock switches.
Off-alignment of primary interlock
Defective secondary interlock S/W
Turntable motor does
not rotate.
Open or loose wiring of
turntable motor.
Replace turntable motor.
Defective turntable motor
Oven stops operation
during cooking
Open or loose wiring of primary
interlock switch
Adjust door and latch switches.
Operation of thermal cutout
(Magnetron)
Sparks
Metallic ware or cooking dishes
touching on the oven wall
Inform the customer : Do not use any type of
cookware with metallic trimming
Ceramic ware trimmed with gold or
silver powder also causes sparks
Loud buzzing noise
can be heard
Loose fan and fan motor
Tighten screws of fan motor.
Tighten screws of H.V.Transformer.
Replace H.V.Diode.
Loose screws on H.V.Transformer
Shorted H.V.Diode
Microwave
output is low
Decrease in power source voltage
Consult electrician.
Open or loose wiring of magnetron
filament circuit.
(Intermittent oscillation)
Aging of magnetron
Fan motor turns
on when plugged in
Loose wiring of door sensing switch
Consult electrician.
Oven does not
operate and return to
the plugged
in mode
Defective Ass’y PCB
Replace PCB main.
Noise from the
turntable motor when
it starts to operate.
Noise may result from the motor
Replace turntable motor.
Uneven cooking
Uneven intensity of microwave due
to its characteristics
Wrap thinner parts of the food with aluminum foil.
se plastic wrap or cover with a lid.
Stir once or twice while cooking foods such as
soup, cocoa, or milk.
Microwave output is low . (Oven takes longer time to cook food .)
Oven can program
but timer does
not start
Open or loose wiring of secondary
interlock switch
Adjust door and interlock switches.
Off-alignment of primary interlock
Defective secondary interlock S/W
Turntable motor does
not rotate.
Open or loose wiring of
turntable motor.
Replace turntable motor.
Defective turntable motor
Oven stops operation
during cooking
Open or loose wiring of primary
interlock switch
Adjust door and latch switches.
Operation of thermal cutout
(Magnetron)
Sparks
Metallic ware or cooking dishes
touching on the oven wall
Inform the customer : Do not use any type of
cookware with metallic trimming
Ceramic ware trimmed with gold or
silver powder also causes sparks
Loud buzzing noise
can be heard
Loose fan and fan motor
Tighten screws of fan motor.
Tighten screws of H.V.Transformer.
Replace H.V.Diode.
Loose screws on H.V.Transformer
Shorted H.V.Diode
Microwave
output is low
Decrease in power source voltage
Consult electrician.
Open or loose wiring of magnetron
filament circuit.
(Intermittent oscillation)
Aging of magnetron
Fan motor turns
on when plugged in
Loose wiring of door sensing switch
Consult electrician.
Oven does not
operate and return to
the plugged
in mode
Defective Ass’y PCB
Replace PCB main.
Noise from the
turntable motor when
it starts to operate.
Noise may result from the motor
Replace turntable motor.
Uneven cooking
Uneven intensity of microwave due
to its characteristics
Wrap thinner parts of the food with aluminum foil.
se plastic wrap or cover with a lid.
Stir once or twice while cooking foods such as
soup, cocoa, or milk.
Fan motor turns on when plugged in .
Oven can program
but timer does
not start
Open or loose wiring of secondary
interlock switch
Adjust door and interlock switches.
Off-alignment of primary interlock
Defective secondary interlock S/W
Turntable motor does
not rotate.
Open or loose wiring of
turntable motor.
Replace turntable motor.
Defective turntable motor
Oven stops operation
during cooking
Open or loose wiring of primary
interlock switch
Adjust door and latch switches.
Operation of thermal cutout
(Magnetron)
Sparks
Metallic ware or cooking dishes
touching on the oven wall
Inform the customer : Do not use any type of
cookware with metallic trimming
Ceramic ware trimmed with gold or
silver powder also causes sparks
Loud buzzing noise
can be heard
Loose fan and fan motor
Tighten screws of fan motor.
Tighten screws of H.V.Transformer.
Replace H.V.Diode.
Loose screws on H.V.Transformer
Shorted H.V.Diode
Microwave
output is low
Decrease in power source voltage
Consult electrician.
Open or loose wiring of magnetron
filament circuit.
(Intermittent oscillation)
Aging of magnetron
Fan motor turns
on when plugged in
Loose wiring of door sensing switch
Consult electrician.
Oven does not
operate and return to
the plugged
in mode
Defective Ass’y PCB
Replace PCB main.
Noise from the
turntable motor when
it starts to operate.
Noise may result from the motor
Replace turntable motor.
Uneven cooking
Uneven intensity of microwave due
to its characteristics
Wrap thinner parts of the food with aluminum foil.
se plastic wrap or cover with a lid.
Stir once or twice while cooking foods such as
soup, cocoa, or milk.
Oven does not operate and return to the plugged in mode .
Oven can program
but timer does
not start
Open or loose wiring of secondary
interlock switch
Adjust door and interlock switches.
Off-alignment of primary interlock
Defective secondary interlock S/W
Turntable motor does
not rotate.
Open or loose wiring of
turntable motor.
Replace turntable motor.
Defective turntable motor
Oven stops operation
during cooking
Open or loose wiring of primary
interlock switch
Adjust door and latch switches.
Operation of thermal cutout
(Magnetron)
Sparks
Metallic ware or cooking dishes
touching on the oven wall
Inform the customer : Do not use any type of
cookware with metallic trimming
Ceramic ware trimmed with gold or
silver powder also causes sparks
Loud buzzing noise
can be heard
Loose fan and fan motor
Tighten screws of fan motor.
Tighten screws of H.V.Transformer.
Replace H.V.Diode.
Loose screws on H.V.Transformer
Shorted H.V.Diode
Microwave
output is low
Decrease in power source voltage
Consult electrician.
Open or loose wiring of magnetron
filament circuit.
(Intermittent oscillation)
Aging of magnetron
Fan motor turns
on when plugged in
Loose wiring of door sensing switch
Consult electrician.
Oven does not
operate and return to
the plugged
in mode
Defective Ass’y PCB
Replace PCB main.
Noise from the
turntable motor when
it starts to operate.
Noise may result from the motor
Replace turntable motor.
Uneven cooking
Uneven intensity of microwave due
to its characteristics
Wrap thinner parts of the food with aluminum foil.
se plastic wrap or cover with a lid.
Stir once or twice while cooking foods such as
soup, cocoa, or milk.