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R - 4 2 0 E K
CHECKING CONTROL UNIT
(1) Disconnect the power supply cord, and then remove outer case.
(2) Open the door and block it open.
(3) Discharge high voltage capacitor.
(4) Disconnect the sensor connector that is mounted to control panel.
(5) Then connect the dummy resistor circuit (see fig.) to the sensor connector of control panel.
(6) Disconnect the leads to the primary of power transformer.
(7) Ensure that these leads remain isolated from other components and oven chassis by using insulation
tape.
(8) After that procedure, re-connect the power supply cord.
(9) Check the sensor cook operation proceed as follows:
9-1 Touch REHEAT SENSOR pad once.
9-2 The control panel is in the sensor cooking operation.
9-3 After approximately 50 seconds, push plunger of select switch for more than 3 seconds. This
condition is same as judgement by AH sensor.
9-4 After approximately 3 seconds, the display shows "xx.xx" which is remaining cooking time, and
the display count down.
If the above is not the case, the control unit is probably defective.
If the above is proper, the AH sensor is probably defective.
(10)Disconnect the power supply cord, and then remove outer case.
(11)Open the door and block it open.
(12)Discharge high voltage capacitor.
(13)Reconnect the sensor connector that is mounted to control panel.
(14)Carry out the necessary repair.
(15)Reconnect all leads removed from components during testing and repairing.
(16)Re-install the outer case (cabinet)
(17)Reconnect the power supply cord after the outer case is installed. Run the oven and check all
functions
(18)Carry out the "water load cooking test" again and ensure that the oven work properly.
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
