Sharp R-390B Service Manual page 16

R-390B
PROCEDURE
LETTER
The meter should indicate 230 - 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 operation.
DC. voltage indicated ............. Defective relay.
DC. voltage not indicated ........ Check diode which is connected to the relay coil. If diode is good,
RELAY SYMBOL
RY1
RY2
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
1
2
3
4
NOTE: *At the time of making these repairs,
make a visual inspection of the
varistor. Check for burned damage
and examine the transformer with a
tester for the presence of layer short-
circuit (check the primary coil resist-
ance). If any abnormal condition is
detected, replace the defective parts.
O AH SENSOR TEST
Checking the initial sensor cooking condition
(1) The oven should be plugged in at least two 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 "INSTALLATION
INSTRUCTIONS" of the operation manual.
(4) Exhaust vents are provided on the back of the unit for proper cooling and air flow in the cavity. To
permit adequate ventilation, be sure to install so as not to block these vents. There should be some
space for air circulation.
(5) Be sure the exterior of the cooking container and the interior of the oven are dry. Wipe off any
moisture with a dry cloth or paper towel.
(6) The Sensor works with food at normal storage temperature. For example, chicken pieces would
be at refrigerator temperature and canned soup at room temperature.
(7) Avoid using aerosol sprays or cleaning solvents near the oven while using Sensor settings. The
sensor will detect the vapour given of by the spray and turn off before food is properly cooked.
(8) If the sensor has not detected the vapour of the food, ERROR will appear and the oven will shut
off.
TEST PROCEDURES
power unit is defective.
OPERATIONAL VOLTAGE
Approx. 25.2V D.C.
Approx. 24.3V D.C.
OCCURRENCE
The rated AC voltage is not present between
Pin No. 3 of the 2-pin connector (A) and the
common terminal of the relay RY2.
The rated AC voltage is present at primary
side of low voltage transformer.
Only pattern at "a" is broken.
Pattern at "a" and "b" are broken.
COMPONENT TEST
CONNECTED COMPONENTS
Oven lamp / Turntable motor / Cooling fan motor
Power transformer
CAUSE OR CORRECTION
Check supply voltage and oven power cord.
Low voltage transformer or secondary circuit defective.
Check and repair.
*Insert jumper wire J1 and solder.
*Insert the coil RCILF2003YAZZ between "c" and "d".
BROWNER
COM
d
AC
3
A - CN
14
HVT
b
c
(J1)
COM AC
a
TTM FM OL
VH
1
1
3 XH