R-21ATP - Sharp Home Appliance Service Manual (repair manual). Page 8

6

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.

TEST PROCEDURE

CONDITION

PROBLEM

POSSIBLE CASE

AND 

DEFECTIVE PARTS

Home fuse or circuit 
breaker blows when 
power cord is plugged into 
wall outlet.

Fuse M10A 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 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 
p r o p e r l y   w h e n  
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

HIGH VOLTAGE TRANSFORMER

H.V. RECTIFIER ASSEMBLY

HIGH VOLTAGE CAPACITOR

THERMAL CUT-OUT

1ST. INTERLOCK SWITCH

LATCH SWITCH

FUSE M10A

HIGH VOLTAGE 

FUSE

NOISE FILTER

TOUCH CONTROL PANEL

KEY UNIT

EXCEED MAX. HEATING TIME

RELAY (RY3)

RELAY (RY2)

FOIL PATTERN ON P.W.B.

LOW VOLTAGE

WRONG OPERATION

DIRTY OVEN CAVITY

MISADJUSTMENT SWITCH

SHORTED IN POWER CORD

OVEN LAMP OR SOCKET

COOLING FAN MOTOR

ANTENNA MOTOR

SHORT OR OPENED WIRING

MONITOR SWITCH

2ND. INTERLOCK RELAY CONTROL SWITCH