Samsung CE745GR service manual Troubleshooting, Electrical Malfunction

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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.

1. Open or loose lead wire harness

 

Check fan motor when thermal cutout is defective.

Fuse is OK.

2. Open thermal cutout (Magnetron)

 

 

No display and no operation at all.

3. Open low voltage transformer

 

Check Ass'y PCB when LVT is defective.

 

4.

Defective Ass'y PCB

 

 

 

 

 

 

No display and no operation at all.

1. Shorted lead wire harness

 

Check adjustment of primary, interlock monitor,

Fuse is blown.

2. Defective primary latch switch (NOTE 1)

 

door sensing switch.

 

3.

Defective monitor switch (NOTE1)

 

 

 

4.

Shorted HVCapacitor

 

 

 

5.

Shorted HVTransformer (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 HVTransformer is replaced, check diode and magnetron also.

 

 

 

 

Oven does not accept

1. Key input is not in-Sequence

Refer to operation procedure.

key input (Program)

2. Open or loose connection of membrane

 

 

 

key pad to Ass'y PCB

 

 

3.

Shorted or open membrane panel

 

 

4.

Defective Ass'y PCB

Replace PCB main.

 

1.

Off-alignment of latch switches

Adjust door and 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

 

Timer starts countdown but no

cause magnetron to lower output and/or

 

microwave oscillation.

intermittent oscillation.

 

(No heat while oven lamp and

3. Defective high voltage components

Check high voltage component according to

fan motor turn on.)

 

H.V.Transformer

component test procedure and replace if it is

 

 

H.V.Capacitor

defective.

 

 

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

Replace PCB main.

 

 

 

 

 

Samsung Electronics

6-1

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Contents Microwave Oven Page Safety precautions PrecautionSpecial High Voltage Precautions Special Servicing PrecautionsSpecifications Table of SpecificationsComparison Chart Features & External Views Operating InstructionsControl Panel Disassembly and Reassembly Replacement of Magnetron, Motor Assembly and LampReplacement of High Voltage Transformer Removal of Door Assembly Replacement of Door AssemblyReplacement of Drive Motor Replacement of FuseRemoval of Control Box Assembly Replacement of Control Circuit BoardMagnetron Alignment and AdjustmentsHigh Voltage Transformer Low Voltage TransformerHigh Voltage Diode Main Relay and Power Control RelayPrecaution High Voltage CapacitorLeakage Measuring Procedure Output Power of MagnetronMicrowave Heat Distribution Heat Evenness Electrical Malfunction TroubleshootingTroubleshooting Exploded Views Exploded Views and Parts ListParts No Description/Specification Qty Remarks Main Parts ListParts No Description/Specification Qty Remarks Old Parts No Control Parts ListBody Latch Parts List Description/Specification QtyStandard Parts List P.C.B Diagrams C.B DiagramsParts No Description / Specification Qty Remarks P.C.B Parts ListSchematic Diagrams Schematic Diagrams