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R1900M

5 – 1

R1900M

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 Procedure“ section.

IMPORTANT: 

If the oven becomes inoperative because of a blown fuse F10, check the monitor switches (1), (2), primary interlock relay RY1, door sensing switch
and secondary interlock switches (1), (2), before replacing the fuse F10. 

Never touch any part in the circuit with your hand or an uninsulated tool while the power supply is connected.

R1900M

5 – 2

Home

fuse

blows

when

power

cord

is

plugged

into

wall

receptacle

It

seems

that

the

output

power

is

lower

or

higher

than

the

rated

one.

"

.

"

does

not

appear

in

display

when

power

cord

is

first

plugged

into

wall

receptacle.

Oven

lamp

does

not

go

on

for

1

minute

after

door

is

opened.

Oven

lamp

and

antenna

motors

do

not

go

on

in

cook

cycle.

Oven

goes

into

a

cook

cycle

but

shuts

down

before

and

off

cooking

cycle.

Oven

does

not

go

into

cook

cycle

when

START

pad

is

touched.

Low

or

no

power

is

produced

during

cooking

condition.

(The

food

is

heated

incompletely

or

not

heated

at

all.)

Variable

cooking

does

not

operates

properly,

except

HIGH

power

functions.

Fan

motor

does

not

operate.

Exhaust

fan

does

not

operate.

Exhaust

motor

does

not

operate.

Oven

doen

not

go

into

cook

cycle

when

START

pad

on

the

door

is

touched.

OFF

CONDITION

CONDITION

PROBLEM

COOKING

CONDITION

POSSIBLE

CAUSE

A

ND

DEFECTIVE

PARTS

TEST

P

ROCEDURE

MAGNETRON(1),

(2)

POWERTRANSFORMER

(1),(2)

H.V.RECTIFIER

ASSEMBLY

(1),(2)

HIGHVOLTAGE

CAPACITOR(1),

(2)

SECONDARYINTERLOCK

SWITCH(1),

(2)

PRIMARYINTERLOCK

SYSTEM

DOORSENSING

SWITCH

MONITORSWITCH

(1),(2)

WEAKPOINT

(inNoise

filter)

MAGNETRONTEMP.

FUSE(1),

(2)

OVENTEMPERATURE

FUSE

OVENLAMP

OR

SOCKET

FANMOTORS

EXHAUSTFAN

EXHAUSTMOTOR

FUSEF10

(1),(2)

WEAKPOINTS

(forFan

motors)

WEAKPOINT

(forExhaust

fanm

otor)

EXHAUSTTHERMISTOR

MAGNETRONTHERMISTOR

NOISEFILTER

KEYUNITS

POWERUNIT

RELAYUNIT

CONTROLUNIT

SWITCHUNIT.

AIRFLOW

BLOCKED

LOOSEWIRING

SHORTIN

POWERSUPPLY

CORD

NOPOWER

AT

OUTLET

LOWPOWER

SUPPLYVOLTAGE

AB

C

D

E

F

F

G

J

KK

H

I

I

M

L

O

Q

R

P

N

Weak

point

(in

noise

filter)

blows

when

power

c

ord

is

p

lugged

into

wall

receptacle.

R1900M

5 – 3

SPECIFICATION OF ERROR

When a basic performance and the function are ruined

Displaying  and heating stop

EE0, EE1, EE2, EE3, EE8

When the dangers of the state of the high temperature and the ignition, etc. are 
foreseen

Displaying  and heating stop

EE7

When you mistake the setting of the heating time

Operation stop

EE9

When neither the power supply nor the environmental condition are proper

Operation stop

EE4, EE5, EE6

When informing of the exchange time of parts

Display Only

CC1, CC2, CC3, CC4



–

MG1 exchange time information

Using time of MG1

MG1



–

MG2 exchange time information

Using time of MG2

MG2



–

Exhaust Fan motor exchange time information Using time of Exhaust motor

Exhaust motor



–

T/C unit exchange time information

Using number of times of RY2/RY3

Relay unit

A

TEST PROCEDURE

POSSIBLE CAUSE

AND

DEFECTIVE PARTS

B D C E

F H I K L M

R P S S T

EE0
EE0
EE0
EE0
EE0
EE0
EE0

EE1

EE1

EE2

EE2

EE3

EE3

EE3

EE4
EE5

EE6
EE6

EE60

EE7

EE7
EE7

EE8

EE8

EE8

EE8
EE8

EE8
EE8
EE8
EE8

EE9

Magnetron

1and

/or

2

Power

transformer

1

&

2

High

voltage

capacitor

1

and

/or

2

H.V.rectifier

assembly

1

and/or

2

Secondary

interlock

switch

1

a

nd/or

Primary

interlock

Fuse

12A

1

and/or

2

Weak

points

for

F

an

motors

(DC24V)

Magnetron

temp.

fuse

1

and/or

2

Magnetron

thermistor

1

and/or

2

Exhaust

thermistor

Fan

m

otors

Exhaust

motor

Antenna

motor

1

a

nd/or

2

Air

flow

blocked

Low

or

High

power

supply

voltage

No

load

or

small

load

operation

Loose

wiring

Exceeding

of

maxmum

cooking

time

Burned

food

Relay

unit

Control

unit

Antenna

sensor

(1)

(Upper)

Antenna

sensor

(2)

(Lower)

Microwave

sensor

Frequency

of

power

supply

is

high.

EE 1

Failer of high voltage circuit 1

EE 2

Failer of high voltage circuit 2

EE 3

Failer of high voltage circuit 1&2

EE 4

Too high of input voltage(+13%)

EE 5

Too low of input voltage(-13%)

EE 7

Food burned (temp., too high)

EE 8

Melted contacts of relays

EE 9

Over maximum cooking time

EE 10

EEPROM error

EE 11

Life end of magnetron 1

EE 21

Life end of magnetron 2

EE 31

Life end of magnetron 1&2

EE 81

Life end of relays RY2/RY3

EE 83

Over Current error

EE 14

MG1 Cooling Fan lock judge

EE 24

MG2 Cooling Fan lock judge

EE 44

Exhaust motor lock judge

EE 54

Life end of exhaust motor

EE 15

MG1 antenna rotation error

EE 25

MG2 antenna rotation error

EE 35

MG1/2 antenna rotation error

EE 16

MG1 thermistor open

EE 26

MG2 thermistor open

EE 17

MG1 temperature, too high

EE 27

MG2 temperature, too high

EE 18

Magnetron 1

EE 28

Magnetron 2

EE 38

Magnetron 1& 2

EE 29

Exhaust thermistor open/short

EE 19

No food

EE 39
EE 60

Small food
Not correct frequency

Error history

display

Usual error

display

Content of error