R-2S56
14
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
J
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 in one unit, and troubleshooting by unit
replacement is described according to the symptoms indicated.
1. Tact Switch.
The following symptoms indicate a defective tact switch. Replace the tact switch.
a) When touching the tact switches, a certain tact switch produces no signal at all.
b) When touching the tact switches, sometimes a tact switch produces no signal.
2. Control Panel
The following symptoms may indicate a defective control unit. Before replacing the control unit,
perform the tact switch test (Procedure K) to determine if control unit is faulty.
2-1 In connection with tact switches.
a) When touching the tact switches, a certain group of tact switches do not produce a signal.
b) When touching the tact switches, no tact switches produce a signal.
2-2 In connection with indicators
a) At a certain digit, all or some segments do not light up.
b) At 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.
2-3 Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Cooking is not possible.
K
TACT SWITCH TEST
If the display fails to clear when the STOP/CLEAR tact switch is depressed, first verify that the door
sensing switch(stop switch) operates properly; that is the contacts are closed when the door is closed
and open when the door is open. If the door sensing switch(stop switch) is good, make sure the door
sensing switch is closed (either close the door or short the door sensing switch connecter). Use the tact
switch matrix indicated on the control panel schematic and
place a jumper wire between the pins that correspond to the
STOP/CLEAR tact switch making momentary contact. If
the control unit responds by clearing with a beep, the tact
switch is faulty and must be replaced. If the control unit
does not respond, it is a faulty and must be replaced. If a
specific pad does not respond, the above method may be
used (after clearing the control unit) to determine if the
control unit or tact switch is at fault.
SW1 10
SW2 1
SW3 10
SW4
SW6
SW7
SW5
MIN.
MIN.
SEC.
AUTO COOK
/DEFROST
INSTANT
COOK
START
STOP
CLEAR
POWER
LEVEL
SERVES
L
RELAY TEST
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin Nos. 3 and 5 of the 3 pin connector (A) on the
control unit with an A.C. voltmeter.
The meter should indicate 240 volts, if not check oven circuit.
RY1 and RY2 Relay Test
These relays are operated by D.C. voltage
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking or convection cooking
operation.
DC. voltage indicated .................... Defective relay.
DC. voltage not indicated . ............ Check diode which is connected to the relay coil. If diode is good,
control unit is defective.
