R-4H54
TEST PROCEDURES (CONT’D)
PROCEDURE
LETTER
COMPONENT TEST
T2”C
Heat up for 49 sec.
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 di-
vided into two units, Control Unit and Key Unit.
1. Key Unit.
The following symptoms indicate a defective key unit. Replace the 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.
2. Control Panel
The following symptoms indicate a defective control unit. Repair the control unit.
2-l In connection with pads.
a) When touching the pads, a certain group of pads do not produce a signal.
b) When touching the pads, no pads 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) Clock does not operate properly.
c) Cooking is not possible.
d) Proper temperature measurement is not obtained.
RELAY TEST
Remove the outer case and check voltage between Pin Numbers 3 and 5 of the 5-pin connector
(A) on the control unit with an A.C. voltmeter.
The meter should indicate 240 volts, if not check oven circuit.
RYI 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 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.
.
RELAY SYMBOL j OPERATIONAL
CONNECTED COMPONENTS
I
VOLTAGE
RYl
/ Approx. 24 V.D.C. / Oven lamp/Turntable motor/Cooling fan motor
RY2
1 ADDrOX. 24 V.D.C. - I Power transformer
10
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