Drawer Microwave
(Models MWD24-2 / MWD30-2)
Troubleshooting Guide
5-8
#813632 - Revision B - December, 2009
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.
•
Disconnect the power supply cord.
•
Remove the outer case cabinet.
•
Open the door and block it open.
•
Discharge high voltage capacitor.
•
If the Fuse is blown, replace power unit.
•
Make a visual inspection of the varistor. Check for burned damage. If the
varistor has been burned, replace the power unit.
•
Examine the touch control transformer with a tester for the presence of
layer short-circuit (check the primary coil resistance which is approximate-
ly 151.6? ± 10%). If any abnormal condition is detected, replace the
touch control transformer.
•
Reconnect all leads removed from components during testing.
•
Re-install the outer case (cabinet).
•
Reconnect the power supply cord after the outer case is installed.
•
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.
•
Disconnect the power supply cord.
•
Remove the outer case cabinet.
•
Open the door and block it open.
•
Discharge high voltage capacitor.
•
Disconnect the leads to the primary of the power transformer.
•
Ensure that these leads remain isolated from other components and oven
chassis by using insulation tape.
•
After that procedure, re-connect the power supply cord.
•
Follow the troubleshooting guide given below for repair.
COMPONENT TEST
PROCEDURE LETTER
E
STEPS
OCCURRENCE
CAUSE OR CORRECTION
1
The rated AC voltage is not present
between Pin Nos. 5 and 7 of the 4-
pin connector (CN-A).
Check supply voltage and oven
power cord.
2
The rated AC voltage is present at
primary side of touch control trans-
former.
Touch control transformer or sec-
ondary circuit defective.Check and
replace touch control transformer or
power unit.
•
Disconnect the power supply cord, and then remove outer case.
•
Open the door and block it open.
•
Discharge high voltage capacitor.
•
Reconnect all leads removed from components during testing.
•
Re-install the outer case (cabinet).
•
Reconnect the power supply cord after the outer case is installed.
•
Run the oven and check all functions.
