SAMSUNG M197DFR Service Manual Troubleshooting
6. Troubleshooting
PRECAUTION
1. CHECK GROUNDING BEFORE CHECKING FOR TROUBLE.
2. BE CAREFUL OF THE HIGH VOLTAGE CIRCUIT.
3. DISCHARGE THE HIGH VOLTAGE CAPACITOR.
4. WHEN CHECKING THE CONTINUITY OF THE SWITCHES OR TRANSFORMER, DISCONNECT ONE LEAD
WIRE FROM THESE PARTS AND THEN CHECK CONTINUITY WITHOUT THE POWER SOURCE ON. TO
DO OTHERWISE MAY RESULT IN A FALSE READING OR DAMAGE TO YOUR METER.
5. DO NOT TOUCH ANY PART OF THE CIRCUIT OR THE CONTROL CIRCUIT BOARD, SINCE STATIC DISCHARGE MAY DAMAGE IT. ALWAYS TOUCH GROUND WHILE WORKING ON IT TO DISCHARGE ANY
STATIC CHARGE BUILT UP.
6-1 Electrical Malfunction
SYMPTOM CAUSE CORRECTIONS
Oven is dead. Fuse is OK.
No display and no operation
at all .
No display and no operation
at all. Fuse is blown.
Oven does not accept
key input (Program)
Timer starts countdown but
no microwave oscillation.
(No heat while oven lamp
and fan motor turn on.)
1. Open or loose lead wire harness
2. Open thermal cutout (Magnetron)
3. Open low voltage transformer
4. Defective Ass’y PCB
1. Shorted lead wire harness
2. Defective primary latch switch (NOTE 1)
3. Defective monitor switch (NOTE1)
4. Shorted H.V.Capacitor
5. Shorted H.V.Transformer (NOTE2)
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 2: When H.V.Transformer is replaced, check diode and magnetron also.
1. Key input is not in-Sequence
2. Open or loose connection of membrane
key pad to Ass’y PCB
3. Shorted or open membrane panel
4. Defective Ass’y PCB
1. Off-alignment of latch switches
2. Open or loose connection of high voltage circuit especially magnetron filament circuit
NOTE: Large contact resistance will bring
lower magnetron filament voltage
and cause magnetron to lower output and/or intermittent oscillation.
3. Defective high voltage components
H.V.Transformer H.V.Capacitor
H.V.Diode, H.V.Fuse Magnetron
4. Open or loose wiring of power relay
5. Defective primary latch switch
6. Defective power relay or Ass’y PCB
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.
Refer to operation procedure.
Replace PCB main.
Adjust door and latch switches.
Check high voltage component according to component test procedure and replace if it is
defective.
Replace PCB main.
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6-1 Electrical Malfunction(continued)
SYMPTOM CAUSE CORRECTIONS
Oven lamp and fan motor
turn on
Oven can program but timer
does not start.
Microwave output is low;.
Oven takes longer time to
cook food.
Fan motor turns on when
plugged in
Oven does not operate and
return to the plugged in
mode.
Loud buzzing noise can be
heard.
Turntable motor does not
rotate.
1. Misadjustment or loose wiring of primary latch switch
2. Defective primary latch switch
1. Open or loose wiring of secondary
interlock switch
2. Off-alignment of primary interlock
3. Defective secondary interlock S/W
1. Decrease in power source voltage.
2. Open or loose wiring of magnetron filament circuit. (Intermittent oscillation)
3. Aging of magnetron
Loose wiring of door sensing switch Check wire of door sensing switch.
Defective Ass’y PCB Replace PCB main.
1. Loose fan and fan motor
2. Loose screws on H.V.Transformer
3. Shorted H.V.Diode
1. Open or loose wiring of turntable motor.
2. Defective turntable motor.
Adjust door and latch switches.
Adjust door and interlock switches.
Consult electrician.
Tighten screws of fan motor.
Tighten screws of H.V.Transformer.
Replace H.V.Diode.
Replace turntable motor.
Oven stops operation during cooking
Sparks 1. Metallic ware or cooking dishes touch-
Uneven cooking Uneven intensity of microwave due to its
Noise from the turntable
motor when it starts to operate.
Radio Voice does not sound 1. Problem of the Speaker
Voice Recorder does not
work
1. Open or loose wiring of primary interlock switch
2. Operation of thermal cutout(Magnetron)
ing on the oven wall.
2. Ceramic ware trimmed with gold or
silver powder also causes sparks.
characteristics.
Noise may result from the motor. Replace turntable motor.
2. Defect of Contacting with Connecter
3. Problem of internal material in Tuner
1. Problem of the Speaker
2. Defect of Contacting with Connecter
3. Problem of internal material in Tuner
Adjust door and latch switches.
Inform the customer.
Do not use any type of cookware
with metallic trimming.
Wrap thinner parts of the food with
aluminum foil.Use plastic wrap or
cover with a lid.Stir once or twice
while cooking foods such as soup,
cocoa, or milk.
1. Replacing the Speaker
2. Check the contacting point of
Connecter
3. Replacing the Tuner ass’y
1. Replacing the Speaker
2. Check the contacting point of
Connecter
3. Replacing the Tuner ass’y
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