R-270KM (serv.man2) - Sharp Home Appliance Service Manual (repair manual). Page 9

R2

70WM

7 – 1

R269WM

Service Manual

 

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 Pro-
cedure"section.

IMPORTANT:

If the oven becomes inoperative because of a blown fuse 

10A in the

1st. latch switch - relay (RY1) - 2nd. interlock relay (RY2) - monitor
switch circuit, check the 1st. latch switch, relay (RY1), 2nd. interlock
relay (RY2) and monitor switch before replacing the fuse 

10A.

MAGNETRON

HIGH

VOLTAGE

TRANSFORMER

H.V.

RECTIFIER

ASSEMBLY

HIGH

VOLTAGE

WIRE

HIGH

VOLTAGE

CAPACITOR

1ST.

LATCH

SWITCH

2ND.

INTERLOCK

RELAY

CONTROL

SWITCH

MONITOR

SWITCH

TEMPERATURE

FUSE

1

20C

(OVEN)

FAN

MOTOR

TURNTABLE

MOTOR

FUSE

 10

A

TOUCH

CONTROL

PANEL

RELAY

(RY-1)

RELAY

(RY-2)

FOIL

PATERN

ON

P.W.B.

POWER

SUPPLY

CORD

SHORTED

WIRE

HARNESS

OPENED

WIRE

HARNESS

OVEN

LAMP

WALL

OUTLET

MISADJUSTMENT

SWITCH

HOME

FUSE

OR

BREAKER

BLOCKED

COOLING

FAN

BLOCKED

VENTILATION

NOISE

FILTER

KEY

UNIT

(MEMBREANE

SWITCH)

H.V.

FUSE

OFF

CONDITION

PROBLEM

CONDITION

POSSIBLE CAUSE

AND

DEFECTIVE PARTS

TEST PROCEDURE

ON

CONDITION

A B C

CK

D

E

E

E F G G H K

M N

I L J

M

RE CK CK RE CK CK CK CK CK

Home fuse blows when pow-

ersupply cord is plugged into

wall outlet.
FUSE 10A blows when

power supply cord is plug-

ged into wall outlet.
":"

does

not appear in

display but power supply cord

is plugged into wall outlet.
Display does not operate

properly when STOP/CLEAR

key is touched.
Oven does not start when

the START key is touched.

(Display appears)
Oven lamp does not light

(Display appears.)
Fan motor does not operate.

(Display appears.)
Turntable motor does not

operate. (Display appears.)
Oven or any electrical parts

does not stop when cooking

time is 0 or STOP/CLEAR

key is touched.
Oven seems to be operating

but little or no heat is pro-

duced in oven load. (Micro-

wave power level is set at

HIGH)
Oven does not seems to be

operating properly when

70%,50%, 30% or 10% is

set. (Oven operates properly

at 100%.)
Oven goes into cook cycle

bu tshuts down before end

of cooking cycle.