Read Sharp R-21AT Service Manual online
12
R-21AT
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
To protect the electronic circuits, this model is provided with a fine foil pattern added to the input circuit
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.
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 J1 and solder.
(CARRY OUT 3D CHECKS BEFORE REPAIR)
(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)
(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 pres-
ence of layer short circuit (check pri-
mary coil resistance).
If any abnormal condition is detected,
replace the defective parts.
burning damage and examine the
transformer with tester for the pres-
ence of layer short circuit (check pri-
mary coil resistance).
If any abnormal condition is detected,
replace the defective parts.
CARRY OUT 4R CHECKS.
N
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(PWB) IS OPEN
(PWB) IS OPEN
(17)
a
b
c
d
(CT1)
(J1)
(J2)
(TB1)
12
P
VRS1
(VRS2)
POWER
7
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