Sharp R-22AT Service Manual

16
R-22AT
R-23AM
R-24AT
To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on the
PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide given below
for repair.
Problem: POWER ON, indicator does not light up.
CARRY OUT
3D CHECKS.
STEPS OCCURRENCE CAUSE OR CORRECTION
1 The rated AC voltage is not present at Check supply voltage and oven power cord.
POWER terminal of CPU connector (CN-A).
2 The rated AC voltage is present at primary Low voltage transformer or secondary circuit defective.
side of low voltage transformer. Check and repair.
3 Only pattern at "a" is broken. *Insert jumper wire J24 and solder for R-24AT / R-22AT.
*Insert jumper wire J9 and solder for R-23AM.
(CARRY OUT
3D CHECKS BEFORE REPAIR)
4 Pattern at "a" and "b" are broken. *Insert the coil RCILF2003YAZZ between "c" and "d".
(CARRY OUT 3D CHECKS BEFORE REPAIR)
NOTE: *At the time of these repairs, make a visual inspection of the varistor for burning damage and
examine the transformer with tester for the presence of layer short-circuit (check primary coil
resistance). If any abnormal condition is detected, replace the defective parts.
CARRY OUT
4R CHECKS.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
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 OPERATIONAL VOLTAGE CONNECTED COMPONENTS
RY1 APPROX. 19.0V D.C. Oven lamp, Blower motor and Stirrer motors
RY3 APPROX. 16.0V D.C. High voltage transformer 1
RY4 APPROX. 18.0V D.C. High voltage transformer 2
RY1, RY2 and RY3 Relay Test For R-23AM
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 OPERATIONAL VOLTAGE CONNECTED COMPONENTS
RY1 APPROX. 18.0V D.C. Oven lamp, Blower motor and Stirrer motors
RY2 APPROX. 17.5V D.C. High voltage transformer 1
RY3 APPROX. 17.5V D.C. High voltage transformer 2
CARRY OUT 4R CHECKS.
R PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING
BOARD(PWB) IS OPEN
(J29)
(VRS2)
VRS1
(J24)
(J23)
(9)9(7)5(3)3(1)
RY1
D81
c
a
b
d
S1
S2
23
P
TI
C31
D23
+
–
VRS1
(J9)
(J8)
OL, BM POWER
7531
D21
CN–A
a
c
b
d
R-24AT / R-22AT R-23AM

Sharp R-22AT Specifications