Read Sharp R-254M (serv.man2) Service Manual online
R-254M - 8
When troubleshooting the microwave oven, it is helpful to
follow the Sequence of Operation in performing the checks.
Many of the possible causes of trouble will require that a
specific test be performed. These tests are given a proce-
dure letter which will be found in the “Test Procedure”
section.
follow the Sequence of Operation in performing the checks.
Many of the possible causes of trouble will require that a
specific test be performed. These tests are given a proce-
dure letter which will be found in the “Test Procedure”
section.
IMPORTANT: If the oven becomes inoperative because
of a blown fuse. Check the monitored latch
switch and monitor switch before replac-
ing the F1 fuse.
switch and monitor switch before replac-
ing the F1 fuse.
TROUBLESHOOTING GUIDE
CONDITION
PROBLEM
A
B
C
D
E
E E
F G
H
I
I
J
K
L
L
M
Home fuse blows when power cord
is plugged into wall outlet.
is plugged into wall outlet.
Fuse F1 blows when power cord
is plugged into wall outlet. (Timer
off)
is plugged into wall outlet. (Timer
off)
All letters and indicators do not
appear in display when power cord
is first plugged into wall outlet.
appear in display when power cord
is first plugged into wall outlet.
Display does not operate properly
when Stop/Clear pad is touched.
(Buzzer should sound and " ; " or
time of day should appear in display.
when Stop/Clear pad is touched.
(Buzzer should sound and " ; " or
time of day should appear in display.
Oven lamp does not light, when in
operation.
operation.
Fan motor does not operate.
Turntable motor does not operate.
Oven or electrical parts does not
stop when cooking time is 0 or
Stop/Clear pad is touched.
stop when cooking time is 0 or
Stop/Clear pad is touched.
Oven seems to be operating but
little or no heat is produced in oven
load. (Microwave power level is set
at HIGH.)
little or no heat is produced in oven
load. (Microwave power level is set
at HIGH.)
Oven does not operate properly during
the variable cooking condition except
100% (HIGH) cooking condition.
the variable cooking condition except
100% (HIGH) cooking condition.
Oven goes into cook cycle but
shuts down before end of cooking
cycle.
shuts down before end of cooking
cycle.
Oven stops as soon as the oven is
started.
started.
Fan motor, oven lamp and
turntable motor do not operate at
the same time.
turntable motor do not operate at
the same time.
OFF
CONDITION
COOKING
CONDITION
TEST PROCEDURE
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
MAGNETRON
HIGH VOLTAGE TRANSFORMER
H.V. RECTIFIER
HIGH VOLTAGE CAPACITOR
MONITORED LATCH SWITCH
STOP SWITCH
MONITOR SWITCH
THERMAL CUT-OUT 125
˚C
FUSE F1
NOISE FILTER
FAN MOTOR
TURNTABLE MOTOR
POWER SUPPLY CORD
OVEN LAMP OR SOCKET
SHORTED WIRE HARNESS
OPENED WIRE HARNESS
MIS-ADJUSTMENT SWITCHES
NO POWER AT WALL OUTLET
HVT THERMOSTAT
CONTROL UNIT
KEY UNIT
RELAY RY1
RELAY RY3
FOIL PATTERN ON P.W.B.
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