Panasonic NN-ST678S Troubleshooting Guide, Troubleshooting Oven stops operation during cooking

NN-SD698S / NN-ST678S / NN-ST658W

8 TROUBLESHOOTING GUIDE

DANGER: HIGH VOLTAGES

1.DO NOT RE-ADJUST PRESET CONTROL on the H.V.Inverter (U). It is very dangerous to repair or adjust without proper test equipment because this circuit generates very large current and high voltage. Operating a misaligned inverter circuit is dangerous.

2.Ensure proper grounding before troubleshooting.

3.Be careful of the high voltage circuitry, taking necessary precautions when troubleshooting.

4.Discharge high voltage remaining in the H.V.Inverter (U).

5.When checking the continuity of the switches or the H.V.Inverter, disconnect one lead wire from these parts and then check continuity with the AC plug removed. Doing otherwise may result in a false reading or damage to your meter. When disconnecting a plastic connector from a terminal, you must hold the plastic connector instead of the lead wire and then disconnect it, otherwise lead wire may be damaged or the connector cannot be removed.

6.Do not touch any parts of the circuitry on the digital programmer circuit, since static electric discharge may damage this control panel. Always touch ground while working on this panel to discharge any static charge in your body.

7.120V AC is present on the digital programmer circuit (Terminals of power relay’s and primary circuit of Digital Programmer Circuit). When troubleshooting, be cautious of possible electrical shock hazard.

Before troubleshooting, operate the microwave oven following the correct operating procedures in the instruction manual in order to find the exact cause of any trouble, since operator error may be mistaken for the oven’s malfunction.

8.1.(Troubleshooting) Oven stops operation during cooking

	SYMPTOM	CAUSE		CORRECTIONS
1.	Oven stops in 3 seconds after	No 120V AC is supplied to H.V.Inverter (U) CN702	1.	Latch Switch
	pressing [Start] pad	terminals	2.	Power relay RY1
			3.	Loose lead wire connector CN701, CN702
			4.	H.V. Inverter (U)
	Oven stops in 37 seconds after	H.V.Inverter (U) operates by the control signals	1.	Magnetron
	pressing [Start] pad	from DPC but magnetron is not oscillating	2.	Loose lead wire connector CN703
			3.	H.V. Inverter (U)
	Oven stops in 10 seconds after	Steam sensor circuit is not functioning	1.	Steam sensor
	pressing [Start] pad		2.	DPC
	(Auto sensor cooking)		3.	Open or loose wiring of sensor terminal
			from connector CN2 on DPC
2.	No display and no operation at all.	Most probably loose connection of connectors, or	1.	Allign door, Door Latch Switches
	Fuse is blown.	door latch mechanism is not adjusted properly	2.	Loose wiring connectors

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