Sharp R-4H56, Service Manual

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R-4H56
15
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
replaced. If a specific pad does not respond, the above method may be used ( after clearing the control
unit) to determine if the control unit or key pad is at fault.
L RELAY TEST
KEY UNIT
LESS
G-8 G-7 G-6 G-5 G-4 G-3 G-2 G-1
G-9
G-10
G-11
G-12
Fresh
Vegetables
STOP
CLEAR
AUTO
START
CLOCK
MORE
Frozen
Vegetables
Fish
Fillets
1
6
Desserts
2
7
Casseroles
3
8
4 5
9 0
EASY
DEFROST
Jacket
Potato
REHEAT
SENSOR
SENSOR
COOK
POWER
LEVEL
INSTANT COOK
START
Remove the outer case and check voltage between Pin Nos. 3 and 5 of the 3-pin connector (A) on the
control unit with an A.C. voltmeter.; The meter should indicate 240 volts, if not check oven circuit.
RY1 and RY2 Relay Test
These relays are operated by D.C. voltage.
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
RY1 Approx. 15V.D.C. Oven lamp/ Turntable motor/ Cooling fan motor
RY2 Approx. 24V.D.C. Power transformer
NOTE: At the time of these repairs, make a visual
inspection of the varistor for burning damage
and examine the transformer with tester
presence of layer short-circuit (check primary
coil resistance). If any abnormal condition is
detected, replace the defective parts.
M 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 Low voltage transformer or secondary circuit defective.
of power transformer. Check and repair.
3 Only pattern at "a" is broken. *Insert jumper wire J1 and solder.
4 Pattern at "a" and "b" are broken. *Insert the coil RCILF2003YAZZ between "c" and "d".