Sharp R-4A52 Service Manual page 16

R -4A52
R-4E52
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
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LIVE TEST FOR MOTOR WINDINGS
CAUTION: The following procedure requires the oven to be connected to the supply
1.
2.
3.
4.
5.
6.
7.
8.
9.
and should only be used if the relevant "cold" checks for the motor un-
der test are inconclusive.
CARRY OUT 3D CHECKS
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.)
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.)
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.)
Close the oven door.
Set the power level to HIGH and set the relevant timer for about three (3) minutes.
Note the reading on the meter and carefully observe the motor under test to see if it is turning.
CARRY OUT 3D CHECKS
Remove test meter leads.
1 O.Reconnect the leads to the primary of the power transformer.
If a reading of the line voltage 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
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to the motor should be checked for continuity.
K BLOWN FUSE F M8A
CARRY OUT $J CHECKS
1. If the fuse E M8A is blown, there are any shorts or grounds in electrical parts or wire har-
ness. Check them and replace the defective parts or repair the wire harness.
2. If the fuse E M8A is blown, there is a short in the asymmetric rectifier or there is a ground
in wire harness. A short in the asymmetric rectifier may be occured due to short or ground
in H.V. rectifier, magnetron, power transformer or H.V. wire. Check them and replace the
defective parts or repair the wire harness.
3. If the fuse E M8A is blown when the door is opened, check the upper latch switch, monitor
switch, lower latch switch and monitor resistor.
If the fuse E M8A is blown by incorrect door switching replace the defective switch(s) and
the fuse E M8A.
CARRY OUT 4FJ CHECKS
-&
CAUTION\ Only replace fuse E M8A with the correct value replacement
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