Sharp R-84ST Service Manual page 19

PROCEDURE
LETTER
J FUSE F1 20A
CARRY OUT 3D CHECKS
If the fuse F1 20A is blown, there is a shorts or grounds in electrical parts or wire harness. Check them
and replace the defective parts or repair the wire harness.
CARRY OUT 4R CHECKS
CAUTION: Only replace fuse with the correct value replacement.
K BLOWN FUSE F2 F8A
CARRY OUT 3D CHECKS
1. If the fuse F2 F8A is blown when the door is opened, check the monitored latch switch and monitor
switch.
2. If the fuse F2 F8A is blown by incorrect door switching replace the defective switch(es) and the fuse
F2 F8A.
3. If the fuse F2 F8A is blown, there could be shorts in the asymmetric rectifier or there is a ground in
wire harness. A short in the asymmetric rectifier may be occurred due to short or ground in H.V.
rectifier, magnetron, high voltage transformer or H.V. wire. Check them and replace the defective
parts or repair the wire harness.
CARRY OUT 4R CHECKS
CAUTION: Only replace fuse F2 F8A with the correct value replacement.
L TOP AND BOTTOM GRILL HEATING ELEMENT TEST
CARRY OUT 3D CHECKS
Before carrying out the following tests make sure the heating element is cool completely.
1. Resistance of heating element.
Disconnect the wire leads to the heating element to be tested. Using ohmmeter with low resistance
range. Check the resistance across the terminals of the heating element as described in the following
table.
2. Insulation resistance.
Disconnect the wire leads to the heating element to be tested. Check the insulation resistance
between the element terminal and cavity using a 500V - 100MΩ insulation tester. The insulation
resistance should be more than 10M&ohm in the cold start.
If the results of above test 1 and/or 2 are out of above specifications, the heating element is probably
faulty and should be replaced.
CARRY OUT 4R CHECKS
TEST PROCEDURES
COMPONENT TEST
Table: Resistance of heating element
Parts name
Bottom grill heating element
Top grill heating element
R-84ST -
Resistance
Approximately 56 Ω
Approximately 106Ω
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