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12
R-4G75(W)M
R-4G75(B)M
R-4G75(B)M
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
An open circuit thermal cut-out (MG) indicates that magnetron has overheated, this may be due to
restricted ventilation, cooling fan failure or a fault condition within the magnetron or HV circuit.
restricted ventilation, cooling fan failure or a fault condition within the magnetron or HV circuit.
An open circuit thermal cut-out (OVEN) indicates that the foods in the oven may catch fire, this may be due
to over heating produced by unproper setting of the cooking timer or failure of the control panel.
to over heating produced by unproper setting of the cooking timer or failure of the control panel.
An open circuit thermal cut-out (GRILL) indicates that the oven cavity has overheated, this may be due to
no load operation.
no load operation.
CARRY OUT 3D CHECKS
If the fuse 13A is blown, there could be shorts or grounds in electrical parts or wire harness. Check them
and replace the defective parts or repair the wire harness.
and replace the defective parts or repair the wire harness.
CARRY OUT 4R CHECKS
CAUTION: Only replace fuse 13A with the correct value replacement
G
BLOWN FUSE 13A
H
BLOWN FUSE M8A
CARRY OUT 3D CHECKS
1. If the fuse M8A is blown when the door is opened, check the primary latch switch, monitor switch and
monitor resistor.
If the fuse M8A is blown by incorrect door switching replace the defective switch(s) and the fuse M8A.
If the fuse M8A is blown by incorrect door switching replace the defective switch(s) and the fuse M8A.
2. If the fuse M8A is blown, there could be a short in the asymmetric rectifier or there is a ground in wire
harness. A short in the asymmetric rectifier may have 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.
magnetron, power 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 with the correct value replacement.
I
NOISE FILTER TEST
CARRY OUT 3D CHECKS
Disconnect the leads from the terminals of
the noise filter.
Using an ohmmeter, check between the ter-
minals as described in the following table.
the noise filter.
Using an ohmmeter, check between the ter-
minals as described in the following table.
MEASURING POINTS
INDICATION OF OHMMETER
Between N and L
Approx. 680K ohm
Between terminal N and WHITE
Short circuit
Between terminal L and RED
Short circuit
R1: 10M ohm
±
20%
R2: 680K ohm
±
20%
L(min)
Cx
±
20%
Cv
±
20%
1.0mH
0.22
µ
F
0.0047
µ
F
RED
WHT
L
L
R1
L
F6.3A
R2
N
Cx
Cy
M8A
J
MONITOR RESISTOR TEST
If incorrect readings are obtained, replace the noise filter unit.
CARRY OUT 4R CHECKS
CARRY OUT 3D CHECKS
Disconnect the leads from the monitor resistor.
Using an ohmmeter and set on a low range.
Check between the terminals of the monitor resistor as described in the following table.
Using an ohmmeter and set on a low range.
Check between the terminals of the monitor resistor as described in the following table.
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