Samsung CE745GR service manual Troubleshooting, Electrical Malfunction

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