Sharp R-84ST Service Manual page 21

PROCEDURE
LETTER
O RELAY TEST
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin Nos. 1 and 3 of the 4 pin connector (E) on the control
unit with an A.C. voltmeter.
The meter should indicate 230-240 volts, if not check oven circuit.
Relay Test
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation, grill
operation, convection operation or dual operation.
DC. voltage indicated ............. Defective relay.
DC. voltage not indicated ....... Check diode which is connected to the relay coil. If diode is good, control
RELAY SYMBOL
CARRY OUT 4R CHECKS.
P 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 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.
CARRY OUT 3D CHECKS.
STEPS
NOTE: *At the time of these repairs, make a
CARRY OUT 4R CHECKS.
TEST PROCEDURES
COMPONENT TEST
OPERATIONAL VOLTAGE
RY1 Approx. 18.0V D.C.
RY2 Approx. 18.0V D.C.
RY3 Approx. 24.0V D.C.
RY4 Approx. 24.0V D.C.
RY5 Approx. 24.0V D.C.
RY6 Approx. 24.0V D.C.
RY7 Approx. 24.0V D.C.
OCCURRENCE
1 The rated AC voltage is not present between
Pin Nos. 1 and 3 of the 4-pin connector (E).
2 The rated AC voltage is present at primary
side of low voltage transformer.
3 Only pattern at "a" is broken.
4 Pattern at "a" and "b" are broken.
visual inspection of the varistor for burn-
ing damage and examine the trans-
former with tester for the presence of
layer short circuit (check primary coil
resistance).
If any abnormal condition is detected,
replace the defective parts.
R-84ST -
unit is defective.
Oven lamp / Turntable motor
High voltage transformer
Grill (Top) heating element
Bottom heating element
Touch control transformer
Fan motor
Convection motor
Check supply voltage and oven power cord.
Low voltage transformer or secondary circuit defective.
Check and repair.
*Insert jumper wire J1 and solder.
(CARRY OUT 3D CHECKS BEFORE REPAIR.)
*Insert the coil RCILF2003YAZZ between "c" and "d".
(CARRY OUT 3D CHECKS BEFORE REPAIR.)
21
CONNECTED COMPONENTS
CAUSE OR CORRECTION
d
b
a
c
VRS1
F
RY6
POWER