Panasonic manual 4

Oven will not	a)	Check the “A” switch for proper operation	PRO-1
start when the	b)	Check the upper door hook to make sure it is actuating the switch
START pad is	c)	Check the wiring from the “A” switch to the controller (DPU) board
pressed (light	d)	Check for 25 volts on both contacts of the “A” switch (with the door
in the cavity		closed)
and display
present)	If none of the above solves the problem – replace the controller (DPU) board
Oven will not	Most likely, the oven’s memory (programming) has not been locked. Perform		PRO-1
start when	the PROGRAM LOCK procedure. Refer to programming instructions at the		PRO-2
MEMORY	beginning of service manual.
(number) pads
are pressed.
Oven will not	Most likely, the oven is in the PROGRAM LOCK mode. Perform the unlocking		PRO-1
accept any	procedure, as per service manual.		PRO-2
programming
instructions
Fuse opens	Most likely, shorted high voltage capacitor is responsible for this symptom.		PRO-1
immediately	Also check the interlock switch, high voltage diode (for shorts), protector diode		PRO-2
after the	(where installed), high voltage transformer (for shorts)
START pad is
pressed
Oven	a)	Low line voltage	OCS
produces	b)	Aged magnetron (over 2,000 hours of use)	PRO-1
insufficient	c)	One of the magnetrons has open filament	PRO-2
heating power	d)	Intermittent or oxidized magnetron connectors
	e)	One of the high voltage diodes open
	f)	One of the high voltage transformers open
	g)	Change in capacitance of the high voltage capacitor
Loud humming	a)	Shorted high voltage diode	OCS
sound when	b)	Shorted high voltage transformer	PRO-1
oven operates			PRO-2
Arcing in the	a)	Burnt or carbonized food under the bottom ceramic plate or anywhere	OCS
cavity (visible		else in the cavity	PRO-1
and/or	b)	Any pointy or sharp metal objects or areas within the cavity	PRO-2
audible)	c)	Loose rivets of the antenna (OCS models only)