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Troubleshooting
PROCEDURE
LETTER
A
TOUCH CONTROL PANEL ASSEMBLY TEST
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. 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 three units, Control Unit,
Keyboard 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 disassemble as per "Drawer Microwave Disas-
sembly" Page 4-6.
2)
Open the drawer 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.
Keyboard Unit.
1)
Check Keyboard unit connection before replacement.
2)
Reconnect all leads removed from components during testing.
3)
Re-install the covers.
4)
Reconnect the power supply cord after the covers are installed.
5)
Run the oven and check all functions.
The following symptoms indicate a defective keyboard unit:
a)
b)
c)
If the Keyboard unit is defective:
1)
Disconnect the power supply cord, and then remove covers.
2)
Open the drawer and block it open.
3)
Discharge high voltage capacitor.
4)
Replace the Keyboard unit.
5)
Reconnect all leads removed from components during testing.
6)
Re-install the covers.
7)
Reconnect the power supply cord after the covers are installed.
8)
Run the oven and check all functions.
2.
Control Unit
The following symptoms indicate a defective control unit. Before replacing the control unit, per-
form the Keyboard unit test (Procedure B) to determine if control unit is faulty.
1)
In connection with indicators
a)
b)
c)
d)
e)
f)
g)
2)
a)
b)
c)
Drawer Microwave
TEST PROCEDURES
When touching the pads, a certain pad produces no signal at all.
When touching a number pad, two ¿ gures or more are displayed.
When touching the pads, sometimes a pad produces no signal.
At a certain digit, all or some segments do not light up.
At a certain digit, brightness is low.
Only one indicator does not light.
The corresponding segments of all digits do not light up; or they continue to light up.
Wrong ¿ gure appears.
A certain group of indicators do not light up.
The ¿ gure of all digits À icker.
Other possible problems caused by defective control unit.
Buzzer does not sound or continues to sound.
Clock does not operate properly.
Cooking is not possible.
COMPONENT TEST
6-4
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