17
R-520LK
R-520LW
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
Therefore, unlike conventional microwave ovens, proper maintenance cannot be performed
with only a voltmeter and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and Key
Unit, and also the Control Unit is divided into two units, LSI Unit and Power Unit, and troubleshooting
by unit replacement is described according to the symptoms indicated.
Before testing,
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 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.
1. Key Unit.
NOTE ;
1) Re-install the outer case (cabinet).
2) Reconnect the power supply cord after the outer case is installed.
3) Run the oven and check all functions.
The following symptoms indicate a defective key unit.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
H TOUCH CONTROL PANEL ASSEMBLY TEST
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. Before performing this test, make sure that the primary interlock switch and the secondary interlock
relay are operating proper ly, according to the above Switch Test Procedure. Disconnect the wire
lead from the monitor switch (COM) ter minal. Check the monitor switch operation by using the
ohmmeter as follows. When the door is open, the meter should indicate a closed circuit. When the
monitor switch actuator is pushed by a screw driver through the lower latch hole on the front plate
of the oven cavity with the door opened (in this condition the plunger of the monitor switch is pushed
in), the meter should indicate an open circuit. If improper operation is indicated, the switch may
be defective. After testing the monitor switch, reconnect the wire lead to the monitor switch (COM)
terminal and check the continuity of the monitor circuit.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
G MONITOR SWITCH TEST
8. Run the oven and check all functions.
Primary
Interlock S witch Monitor Switch
Scre w D river
Ohmmeter
Red White/W hite