Sharp R-4A68, Service Manual

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R-4A68
13
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
unit is defective.
RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS
RY1 APPROX. 13.5V D.C. Oven lamp / Turntable motor / Cooling fan motor
RY2 APPROX. 13.0V D.C. Power transformer
CARRY OUT 4R CHECKS.
M PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(PWB) IS OPEN
a
b
c
d
1
3
P
RY1
VRS1
29
5
CN-A
1
(J4)
(J1)
T1
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 OCCURANCE 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 J1 and solder.
(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 making these repairs, make
a visual inspection of the varistor. check for
burned damage and examine the trans-
former with a tester for the presence of layer
short-circuit (check primary coil resistance).
If any abnormal condition is detected, re-
place the defective parts.
CARRY OUT 4R CHECKS.