Monitor Resistor Test; Motor Winding Test; Live Test For Motor Windings; Test Procedure - Sharp R-3A53 Service Manual

R-3A53
R-3A530
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER COMPONENT TEST
G MONITOR RESISTOR TEST
CARRY OUT 30 CHECKS.
Disconnect the leads from the monitor resistor or surge resistor.
Using an ohmmeter and set on a low range.
Check between the terminals of the monitor resistor or surge resistor as described in the follow-
ing table.
Table: Resistance
Resistor
I
Resistance
-1
Monitor resistor Approx. O.Sn
I
If incorrect readings are obtained, replace the monitor resistor or surge resistor
CARRY OUT 4R CHECKS.
H 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
IM
otors Resistance
1 F an motor 1 Approximatelv 252 ohms
1 Turntable motor 1 Approximately 13.75 kohms
If incorrect readings are obtained, replace the motor.
(Also refer to test procedure I)
CARRY OUT 4R CHECKS
LIVE TEST FOR MOTOR WINDINGS
CAUTION: The following procedure requires the oven to be connected to the supply
and should only be used if the relevant "cold" checks for the motor un-
der test are inconclusive.
1. CARRY OUT 3D CHECKS
2. Disconnect the leads from the primary of the power transformer. Make sure that the leads
remain isolated from other oven components and chassis. (Use insulation tape if necessary.)
3. Connect a voltmeter, set to 250V AC, across the motor terminals. (Refer to the relevant motor
test procedure or pictorial diagram for the correct terminal numbers.)
4. Arrange the meter in a position where it can be read during the test. (Do not touch the meter,
meter leads or oven circuitry while the oven is active.)
5. Close the oven door.
6. Set the reievant timer for about three (3) minutes, set the power level to HIGH and push the
START button.
7. Note the reading on the meter and carefully observe the motor under test to see if it is turning.
8. CARRY OUT 3D CHECKS
9. Remove test meter leads.
1 O.Reconnect the leads to the primary of the power transformer.
If a reading of 240 volts AC was obtained (step 7) but the motor was not turning then it is faulty
and should be replaced. If the meter indicated that no supply was present then the wiring to the
motor should be checked for continuity.
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