Sharp R-22AM Service Manual page 21

PROCEDURE
LETTER
RELAY SYMBOL
RY1
RY2
RY3
CARRY OUT 4R CHECKS.
R PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING
BOARD(PWB) IS OPEN
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
1
2
3
4
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.
D81
3(1)
TEST PROCEDURES
OPERATIONAL VOLTAGE
APPROX. 18.0V D.C.
APPROX. 17.5V D.C.
APPROX. 17.5V D.C.
OCCURRENCE
The rated AC voltage is not present at
POWER terminal of CPU connector (CN-A).
The rated AC voltage is present at primary
side of low voltage transformer.
Only pattern at "a" is broken.
Pattern at "a" and "b" are broken.
d
VRS1
(VRS2)
a
b
(J23)
c
5(3) 9(7)
R-23AT
COMPONENT TEST
CONNECTED COMPONENTS
Oven lamp, Blower motor and Stirrer motors
High voltage
High voltage
CAUSE OR CORRECTION
Check supply voltage and oven power cord.
Low voltage transformer or secondary circuit defective.
Check and repair.
*Insert jumper wire J24 and solder for R-23AT.
*Insert jumper wire J9 and solder for R-23AM / R-22AM.
(CARRY OUT 3D CHECKS BEFORE REPAIR)
*Insert the coil RCILF2003YAZZ between "c" and "d".
(CARRY OUT 3D CHECKS BEFORE REPAIR)
(J29)
(9)
19
transformer 1
transformer 2
a
d
c
(J9)
b
R-23AM / R-22AM
R-22AM
R-23AM
R - 2 3 A T
D23
–
+
C31