16
R-25AM
M
TOUCH CONTROL PANEL ASSEMBLY TEST
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
The touch control panel consists of circuits including semiconductors such as LSI 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, Switch Unit and Encoder Unit troubleshooting by unit replacement is described
according to the symptoms indicated.
1. Switch Unit Note : Check the lead wire harness connections among big and small switch units
and control unit before replacement.
The following symptoms indicate a defective switch unit. Replace the switch unit.
a) When touching the buttons, a certain button produces no signal at all.
b) When touching the buttons, sometimes a button produces no signal.
2. Encoder Note : Check the lead wire connection between encoder and control unit before
replacement.
The following symptoms indicate a defective encoder. Replace the encoder.
a) When rotating the encoder, the cooking time can not be entered.
3. Control Unit
The following symptoms may indicate a defective control unit. Replacing the control unit. Before
replacing the control unit, perform the switch unit test (Procedure N) to determine if control unit is
faulty.
3-1 Programming problems.
a) When touching the buttons, a certain group of buttons do not produce a signal.
3-2 Display problems.
a) For a certain digit, all or some segments do not light up.
b) For a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
3-3 Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Cooking is not possible.
1. CARRY OUT 3D CHECKS.
2. Remove the switch unit from the control panel, referring to control panel removal.
3. To test the switches (SW1-SW5) on the switch unit, check between the terminals of the connector
CN-F as described in the following table by using ohmmeter when the switches are released and
depressed.
Switches
Terminals
Released
Depressed
SW1
F1 - F4
O.C.
S.C.
SW2
F1 - F5
O.C.
S.C.
SW3
F2 - F4
O.C.
S.C.
SW4
F2 - F5
O.C.
S.C.
SW5
F3 - F4
O.C.
S.C.
4. If incorrect readings are obtained, replace the defective switch.
5. CARRY OUT 4R CHECKS.
N
SWITCH UNIT TEST
O
RELAY TEST
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin Nos. 3 and 5 of the connector (A) on the control
unit with an A.C. voltmeter. The meter should indicate 230 volts, if not check control unit circuity.
O.C. ----- Open Circuit
S.C. ----- Short Circuit
