Chapter 7. Troubleshooting Guide; Troubleshooting Chart - Sharp R-21LCF Service Manual

R21LCF
CHAPTER 7.
R21LCF
TROUBLESHOOTING GUIDE
Never touch any part in the circuit with your hand or an uninsulated tool while the power supply is connected.
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, primary interlock relay (RY1), 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.

[1] TROUBLESHOOTING CHART

T E S T P R OC E DUR E
P OS S IB LE C AS E
DE F E C T IV E P AR T S
P R OB LE M
C ONDIT ION
Home fus e or circuit breaker blows when
power cord is plugged into wall outlet.
OF F
C ONDIT ION
Monitor fus e blows when power cord is
plugged into wall outlet.
Oven lamp does not light, and fan motor
and antenna motor do not operate.
Oven does not go into cook cycle when
Light Up Dial turned.
Oven s eems to be operating but little or
no heat is produced in oven load. (F ood
C OOK ING
incompletely cooked or not cooked at all
C ONDIT ION
at end of cook cycle.)
O ven goes
extremely uneven heating is produced in
oven load (food).
AND
into a cook cycle but
Service Manual
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.
A B C D E F F G
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H I J K L R E R E R E R E R E C K C K C K