R21LTF
7 – 1
R21LTF
Service Manual
CHAPTER 7.
TROUBLESHOOTING GUIDE
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 procedure letter which will be found in the "Test Procedure "section.
IMPORTANT
:
If the oven becomes inoperative because of a blown monitor fuse,
check the monitor switch, relay (RY3), primary interlock relay (RY2),
door sensing switch and secondary interlock switch before replacing
the monitor fuse. If monitor fuse is replaced, the monitor switch must
also be replaced. Use part FFS-BA033WRKZ as an assembly.
IMPORTANT
:
Whenever troubleshooting is performed with the power supply cord
disconnected. It may in, some cases, be necessary to connect the
power supply cord after the outer case has been removed, in this
event,
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Disconnect the leads to the primary of the power transformer.
5) Ensure that the leads remain isolated from other components and
oven chassis by using insulation tape.
6) After that procedure, reconnect the power supply cord.
When the testing is completed,
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Reconnect the leads to the primary of the power transformer.
5) Reinstall the outer case (cabinet).
6) Reconnect the power supply cord after the outer case is installed.
7) Run the oven and check all functions.
[1] TROUBLESHOOTING CHART
Never touch any part in the circuit with your hand or an uninsulated tool while the power supply is connected.
TEST PROCEDURE
CONDITION
PROBLEM
POSSIBLE CASE
AND
DEFECTIVE PARTS
Home fuse or circuit breaker blows when
power cord is plugged into wall outlet.
Monitor fuse blows when power cord is
plugged into wall receptacle.
.
does not appear in display when
power cord is first plugged into wall outlet.
Oven lamp does not light when door is opened.
Oven lamp does not go out when door is
closed.
Oven lamp lights but fan motor and
antenna motor do not operate.
Oven does not go into cook cycle when
START pad is touched
Oven seems to be operating but little or no
heat is produced in oven load. (Food
incompletely cooked or not cooked at all at
end of cook cycle.)
Oven goes into a cook cycle but extremely
uneven heating is produced in oven load (food).
Oven
does
not
cook
properly
when
programmed for Cooking Power 5 mode.
(Operates properly on Cooking Power 10
(HIGH) mode.)
"EE9" Maximum time is exceeded.
OFF
CONDITION
COOKING
CONDITION
ERROR MODE
MAGNETRON
POWER
T
RANSFORMER
H.V.
R
ECTIFIER
ASSEMBLY
HIGH
VOLTAGE
CAPACITOR
THERMAL
CUT-OUT
SECONDARY
INTERLOCK
SWITCH
PRIMARY
INTERLOCK
SYSTEM
MONITOR
SWITCH
MONITOR
FUSE
TOUCH
CONTROL
PANEL
KEY
UNIT
EXCEED
MAX.
HEATING
TIME
RELAY
(RY3)
FOIL
PATTERN
O
N
P
.W.B.
LOW
VOLTAGE
WRONG
OPERATION
DIRTY
O
VEN
CAVITY
NOISE
F
ILTER
SHORTED
IN
POWER
CORD
OVEN
LAMP
OR
SOCKET
COOLING
FAN
MOTOR
ANTENNA
MOTOR
SHORT
OR
OPENED
WIRING
A B
C
D
E
F
F G
H
J
K
L
M CK RE RE RE RE RE CK CK CK I
