Sharp KB-5121KS Service Manual page 17

PROCEDURE
LETTER
8. Reconnect all leads removed from components during testing.
9. Re-install the covers.
10. Reconnect the power source after the cabinets are installed.
11. Run the drawer and check all function.
D DEFROST TEST
WARNING : The unit should be fully assembled before following procedure.
(1) Place one cup of water in the center of the turntable tray in the oven cavity.
(2) Close the door, touch the Stop/Clear (M) pad and touch the Defrost pad on the LCD. Then touch the
Steaks/Chops pad on the LCD. And touch the number pad 5 on the LCD. (Now, weight 0.5lb is set.)
And then touch the start pad on the LCD.
(3) The oven is in Defrost cooking condition.
(4) The oven will operate as follows
(5) If improper operation is indicated, the control unit is probably defective and should be checked.
E PROCEDURES TO BE TAKEN WHEN THE FUSE ON THE PRINTED WIRING BOARD (PWB) IS
OPEN.
To protect the electronic circuits, this model is provided with a fuse added to the primary on the PWB.
1. Fuse check and repairs.
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) If the Fuse is blown, replace power unit.
5) Make a visual inspection of the varistor. Check for burned damage. If the varistor has been burned,
replace the power unit.
6) Examine the touch control transformer with a tester for the presence of layer short-circuit (check
the primary coil resistance which is approximately 60Ω ± 10%). If any abnormal condition is
detected, replace the touch control transformer.
7) Reconnect all leads removed from components during testing.
8) Re-install the covers.
9) Reconnect the power source after the outer case is installed.
10) Run the oven and check all functions.
2. Follow the troubleshooting guide given below, if indicator does not light up after above check and
repairs are finished.
1) Disconnect the power source, and then disassemble as per "COOK TOP/MICROWAVE DRAWER
DISASSEMBLY" page 32.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Disconnect the leads to the primary of the power transformer.
5) Ensure that these leads remain isolated from other components and oven chassis by using
insulation tape.
6) After that procedure, re-connect the power supply cord.
7) Follow the troubleshooting guide given below for repair.
TEST PROCEDURES
WEIGHT 1ST STAGE
LEVEL TIME
0.5lb 60% 20sec.
COMPONENT TEST
2ND STAGE 3RD. STAGE
LEVEL TIME LEVEL
40% 20sec. 30%
15
KB-5121KS/K/W
TIME
45sec.