Sharp KB-5121KS Service Manual page 19

PROCEDURE
LETTER
(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 source after the cabinets are 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. Close the door.
9-4. Touch the UPER MICROWAVE OVEN pad,
SENSOR LOAD pad on the LCD. And touch the number pad 4 once.
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.
(1) Disconnect the power source, and then disassemble as per "COOK TOP/MICROWAVE
DRAWER DISASSEMBLY" page 32.
(2) Open the drawer 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. Close the door.
9-2. Touch the UPER MICROWAVE OVEN pad,
SENSOR LOAD pad on the LCD. And touch the number pad 4 once.
9-3. The control panel is in the sensor cooking operation.
9-4. After approximately 25 seconds, push plunger of select switch for more than 3 seconds. This
condition is same as judgement by AH sensor.
9-5. 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.
Disconnect the power source , and the covers.
(10)
(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.
(15) Reconnect all leads removed from components during testing and repairing.
(16) Re-install the covers.
(17) Reconnect the power source after the cabinets are installed. Run the oven and check all functions.
( 18) Carry out "Water load cooking test" again and ensure that the oven works properly.
R1, R2 :
R3 : 4.3kΩ ± 5% 1/4W
R4 :
TEST PROCEDURES
CHECKING CONTROL UNIT
22Ω ± 1% 1/2W
1MΩ ± 5% 1/4W
To connector (F)
on Control Unit.
1
F-1
2
F-2
3
F-3
CONNECTOR
Sensor Dummy Resistor Circuit
COMPONENT TEST
pad, pad, START MINUTE PLUS pad and the
pad, pad, START MINUTE PLUS pad and the
COM
R1
R3 R4
R2
17
KB-5121KS/K/W
Plunger
NC
NO
COM
NO
NC