Blown Monitor Fuse Test; Power Transformer Test; Failure Codes - Sharp KB-3425LS Service Manual

KB-3425LS/K/W
KB-4425LS/K/W
PROCEDURE
LETTER
M

BLOWN MONITOR FUSE TEST

. Disconnect the power supply cord.
2. Open the drawer and block it open.
3. To discharge high voltage capacitor, wait for 60 seconds.
4. If the monitor fuse is blown when the drawer is opened, check the primary interlock switch, secondary
interlock switch and monitor switch according to the "TEST PROCEDURE" for those switches before
replacing the blown monitor fuse.
CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE, TEST THE SECONDARY INTERLOCK
If the monitor fuse is blown by improper switch operation, the monitor fuse and monitor switch must
be replaced with "monitor fuse and monitor switch assembly" part number FFS-BA08/KIT, even if
the monitor switch operates normally. The monitor fuse and monitor switch assembly is comprised
of a 20 ampere fuse and switch.
5. Reconnect all leads removed from components during testing.
6. Reassemble the unit.
7. Reconnect the power supply cord.
8. Run the oven and check all functions.
N

POWER TRANSFORMER TEST

. Disconnect the power supply cord.
2. Open the drawer and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the primary input terminals and measure the resistance of the transformer with an
ohmmeter. Check for continuity of the coils with an ohmmeter. On the R x  scale, the resistance
of the primary coil should be less than  ohm and the resistance of the high voltage coil should be
approximately 90 ohms; the resistance of the filament coil should be less than  ohm.
5. Reconnect all leads removed from components during testing.
6. Reassemble the unit.
7. Reconnect the power supply cord.
8. Run the oven and check all functions.
(HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO
MEASURE THE FILAMENT AND HIGH VOLTAGE.)
O

FAILURE CODES

The following failure codes will be displayed on the Control Panel.
EE 6
Check thermistor or control unit.
EE 7
Check thermistor or control unit.
EE L
Check lock motor, lock switch (RY 8) or control unit.
SPECAIL FAILURE NOTE:
During the Microwave Drawer operation, if it goes dead, check each Thermal Cut-out first.
This is due to the whole control unit being powered by Line L (refer to Schematic on page 3).
TEST PROCEDURES
SWITCH, STOP SWITCH AND MONITOR SWITCH FOR PROPER OPERATION.
(displayed when oven starts) -
(displayed when oven starts) -
(displayed after 1 minute of cooking or self cleaning) -
COMPONENT TEST
Oven Thermistor is open.
Oven Thermistor is shorted.
28
Lower door lock error.