Read Sharp R-871M Service Manual online
871M - 7
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
C
RELAY TEST
To protect the electronic circuits, this model is provided with a fine foil pattern added to the input
circuiton 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.
circuiton 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)
D
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING
BOARD (PWB) IS OPEN.
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.
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. convection
cooking operation or grill operation.
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation. convection
cooking operation or grill operation.
DC. voltage indicated ............. Defective relay.
DC. voltage not indicated ....... Check diode which is connected to the relay coil. If diode is good,
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. 24.0V D.C.
Oven lamp / Turntable motor
RY2
Approx. 18.0V D.C.
High voltage transformer
RY3
Approx. 18.0V D.C.
Grill heating element (Top grill)
RY4
Approx. 18.0V D.C.
Bottom heating element
RY5
Approx. 24.0V D.C.
Fan motor
RY6
Approx. 24.0V D.C.
Convection fan motor
CARRY OUT 4R CHECKS.
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
primary coil resistance).
If any abnormal condition is de-
tected, replace the defective parts.
burning damage and examine the
transformer with tester for the pres-
ence of layer short circuit (check
primary coil resistance).
If any abnormal condition is de-
tected, replace the defective parts.
CARRY OUT 4R CHECKS.
CN - E
CN - D
D25
a
b
c
d
VRS1
CN - A
RY6
(J1)
1
3
5
31
Click on the first or last page to see other R-871M service manuals if exist.