Sharp R-450C, Service Manual

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R-450C
11
L TOUCH CONTROL PANEL ASSEMBLY TEST
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
CARRY OUT 4R CHECKS.
Table: Thermal cut-out Test
Temperature of "ON" Temperature of "OFF" Indication of ohmmeter
Parts Name condition (closed circuit) (˚C) condition (open circuit) (˚C) (When room temperature
is approx. 20˚C)
Thermal cut-out 145˚C This is not resetable type. Above 145˚C Closed circuit.
Temperature fuse 150˚C This is not resetable type. Above 150˚C Closed circuit.
If incorrect readings are obtained, replace the temperature fuse or thermal cut-out.
An open circuit temperature fuse 150˚C (MG) indicates that the magnetron has overheated, this may
be due to restricted ventilation, cooling fan failure or a fault condition within the magnetron or HV
circuit.
An open circuit thermal cut-out 145˚C (OVEN) indicates that the foods in the oven may catch fire, this
may be due to over heating produced by improper setting of the cooking time or failure of the control
panel.
I MOTOR WINDING TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the motor.
Using an ohmmeter, check the resistance between the two terminals as described in the table below.
Table: Resistance of Motor
Motors Resistance
Fan motor Approximately 295 Ω
Turntable motor Approximately 12.2 k
Ω
If incorrect readings are obtained, replace the motor.
CARRY OUT 4R CHECKS.
CARRY OUT 3D CHECKS.
1. If the fuse M10A is blown, there could be shorts or ground in electrical parts or wire harness.
Check them and replace the defective parts or repair the wire harness.
2. If the fuse M10A is blown when the door is opened, check the 1st. latch switch, 2nd. latch switch,
monitor switch and monitor resistor.
If the fuse M10A is blown by incorrect door switching replace the defective switch(s) and the fuse
M10A.
CARRY OUT 4R CHECKS.
CAUTION: ONLY REPLACE FUSE M10A WITH THE CORRECT VALUE REPLACEMENT
J BLOWN FUSE M10A
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore,
unlike conventional microwave ovens, proper maintenance cannot be performed with only a
voltmeter and ohmmeter. In this service manual, the touch control panel assembly is divided into two
K HIGH VOLTAGE FUSE TEST
CARRY OUT 3D CHECKS.
If the high voltage fuse is blown, there could be a short in the high voltage rectifier or the magnetron.
Check them and replace the defective parts and high voltage fuse.
CARRY OUT 4R CHECKS.
CAUTION: ONLY REPLACE THE HIGH VOLTAGE FUSE WITH THE CORRECT VALUE RE-
PLACEMENT