Sharp R-4H55 Service Manual page 19

R-4H55
R-4X.55
R-4XS5B
TEST PROCEDURES
PROCEDURE
LElTER COMPONENT TEST
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking.
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
RYl Approx. 25V.D.C. Oven lamp/Turntable motor/Cooling fan motor
RY2 Approx. 24V.D.C. Power transformer
N
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.
STEPS OCCURANCE
CAUSE OR CORRECTION
1 The rated voltage is not applied to POWER
Check supply voltage and oven main unit.
terminal of CPU connector (CN-A)
2 The rated voltage is applied to primary side of Power transformer or secondary circuit defective. Check
power transformer. and repair.
I I
3 Only pattern at "a" is broken.
'Insert jumper wire Jl and solder.
I I
4
Pattern at "a" and "b" are broken.
'Insert the coil RCILF2003YAZZ between "c" and 'IS'.
NOTE: At the time of these repairs, make a visual
inspection of the varistor for burning dam-
age and examine the transformer with
tester presence of layer short-circuit
(check primary coil resistance). If any ab-
normal condition is detected, replace the
defective parts.
0 AH SENSOR TEST
Checking the initial sensor cooking condition
(1) The oven should be plugged in at least five minutes before sensor cooking.
(2) Room temperature should not exceed 95'F(35"C).
(3) The unit should not be installed in any area where heat and steam are generated. The unit
should not be installed, for example, next to a conventional surface unit. Refer to the "INSTAL-
LATION Instructions" .
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