20
R - 4 2 6 H S
R - 4 2 6 H K
R -426HW
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
(5) The oven will operate for the first 16 seconds, without generating microwave energy.
NOTE: ERROR will appear if the door is opened or STOP/CLEAR pad is touched during first stage of sensor
cooking.
(6) After approximately 16 seconds, microwave energy is produced.
If ERROR is displayed or the oven does not turn off, replace the AH sensor or check the control unit, refer
to explanation below. If the oven stops after 5 minutes and ERROR is displayed, the AH sensor is normal.
Check other parts except the AH sensor.
TESTING METHOD FOR AH SENSOR AND/OR CONTROL UNIT
To determine if the sensor is defective, the simplest method is to replace it with a new replacement sensor.
(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) Remove the AH sensor.
(5) Install the new AH sensor.
(6) Reconnect all leads removed from components during testing.
(7) Re-install the outer case (cabinet).
(8) Reconnect the power supply cord after the outer case is installed.
(9) Reconnect the oven to the power supply and check the sensor cook operation as follows:
9-1. Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.
9-2. Place the container on the center of tray in the oven cavity.
9-3. Open the door.
9-4. Touch the TIMER/CLOCK pad once and the POWER LEVEL pad twice. Close the door and touch
the START pad once. Open the door and touch the number pads 1 once and the number pad 4.
Close the door and the touch the START pad.
9-5. The control panel is in automatic Sensor operation.
9-6. The oven turns off automatically, and the time for detecting moisture will be displayed.
If new sensor dose not operate properly, the problem is with the control unit, and refer to explanation below.
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 the 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. Open the door. Touch the TIMER/CLOCK pad once and the POWER LEVEL pad twice. Close the
door and touch the START pad once. Open the door and touch the number pads 1 once and the
number pad 4. Close the door and the touch the START pad.
9-2. The control panel is in the sensor cooking operation.
9-3. After approximately 25 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 “ X X . X X “ which is the time for detecting
moisture.
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) Disconnect the dummy resistor circuit from the sensor connector of control panel.
(14) Carry out necessary repair.
