Goldstar Ms-110yg Service Manual

BEFORE SERVICING THE UNIT, READ THE

SAFETY PRECAUTIONS

IN THIS MANUAL.

CAUTION

website: http://www.lgservice.com
e-mail : http://www.lgeservice.com/techsup.html

K

M

MICROWAVE OVEN

SERVICE MANUAL

MODEL: MS-110YG

This device is to be serviced only by properly qualified service personnel.
Consult the service manual for proper service procedures to assure continued safety operation and for precautions to be
taken to avoid possible exposure to excessive microwave energy.

PRECAUTIONS TO BE OBSERVED BEFORE AND
DURING SERVICING TO AVOID POSSIBLE
EXPOSURE TO EXCESSIVE MICROWAVE ENERGY

A) Do not operate or allow the oven to be operated with the door open.

B) Make the following safety checks on all ovens to be serviced before activating the magnetron or other

microwave source, and make repairs as necessary; (1) interlock operation, (2) proper door closing, (3)

seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening of hinges and

latches, (5) evidence of dropping or abuse.

C) Before turning on microwave power for any service test or inspection within the microwave generating

compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment,

integrity, and connections.

D) Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation

and transmission systems shall be repaired, replaced, or adjusted by procedures described in this manual

before the oven is released to the owner.

E) A microwave leakage check to verify compliance with the CSA should be performed on each oven prior to

release to the owner.

SAFETY PRECAUTIONS

(Page)

SAFETY PRECAUTIONS

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Inside front cover

SPECIFICATIONS

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1-1

CAUTIONS

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2-1

INSTALLATIONS

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3-1

OPERATING INSTRUCTIONS

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4-1

FEATURES

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4-1

CONTROL PANEL

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4-1

OPERATING SEQUENCE

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4-2

SCHEMATIC DIAGRAM

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4-3

CIRCUIT DESCRIPTION

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4-4

SERVICE INFORMATION

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5-1

TOOLS AND MEASURING INSTRUMENTS

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5-1

MICROWAVE LEAKAGE TEST

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5-1

MEASUREMENT OF MICROWAVE POWER OUTPUT

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5-3

DISASSEMBLY AND ADJUSTMENT

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5-3

INTERLOCK CONTINUITY TEST

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5-7

COMPONENT TEST PROCEDURE

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5-8

TROUBLE SHOOTING

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5-11

EXPLODED VIEW

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6-1

REPLACEMENT PARTS LIST

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7-1

SCHEMATIC DIAGRAM OF P.C.B.

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8-1

PRINTED CIRCUIT BOARD

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8-2

P.C.B. PARTS LIST

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9-1

CONTENTS

1-1

It is not recommended for commercial purposes.

ITEM

MODEL

Power Requirement

Power Output

Microwave Frequency

Magnetron

Timer

Outside Dimensions

Cavity Dimensions

Net Weight

Shipping weight

Control Complement

Accessories

DESCRIPTION

MS-110YG

120 Volts AC 60 Hz

1,500 Watts (13 A)

Single phase, 3 wire grounded

1,100 Watts full microwave power (IEC60705)

2,450 MHz

2M246

0 ~ 99 min. 99 sec.

20

7

/8” (W) x 123/8” (H) x 151/2” (D)

13

3

/8” (W) x 87/8” (H) x 141/8” (D)

33 lbs (approx.)

35 lbs (approx.)

Touch Control System

Clock : 1:00 - 12:59

Microwave Power for Variable Cooking

Power level

HIGH ----------------------------------------Full power throughout the cooking time

9 (Saute) -------------------------approx. 90% of Full power, 8 (Reheat) --------approx. 80%

7 (Med.-High) --------------------approx. 70%, 6 (Medium) --------approx. 60%

5 (Med.-Low) --------------------approx. 50%, 4 (Defrost) ---------approx. 40%

3 (Low) ---------------------------approx. 30%, 2 (Simmer)--------approx. 20%

1 (Warm)--------------------------approx. 10%

Owner's Guide & Cooking guide

Glass turntable

Rotating ring

SPECIFICATIONS

• DO NOT operate on a 2-wire extension cord during
repair and use.

• NEVER TOUCH any oven components or wiring during
operation.

• BEFORE TOUCHING any parts of the oven, always
remove the power plug from the outlet.

• For about 30 seconds after the oven stops, an electric
charge remains in the high voltage capacitor. When
replacing or checking, you must discharge the high
voltage capacitor by shorting across the two terminals
with an insulated screwdriver.

•

Remove your watches whenever working close to or

replacing the Magnetron.

• DO NOT touch any parts of the control panel circuit. A
resulting static electric discharge may damage this
P.C.B.

• NEVER operate the oven with no load.

• NEVER injure the door seal and front plate of the oven
cavity.

• NEVER put iron tools on the magnetron.

• NEVER put anything into the latch hole and the
interlock switches area.

• Proper operation of the microwave oven requires that
the magnetron be assembled to the waveguide and
cavity. Never operate the magnetron unless it is
properly installed.

• Be sure that the magnetron gasket is properly
installed around the dome of the tube whenever
installing the magnetron.

2-1

CAUTIONS

Unlike other appliances, the microwave oven is
high-voltage and high-current equipment.
Though it is free from danger in ordinary use,
extreme care should be taken during repair.

THE OVEN IS TO BE SERVICED ONLY
BY PROPERLY QUALIFIED SERVICE
PERSONNEL.

MICROWAVE RADIATION

Personnel should not be exposed to the
microwave energy which may radiate from the
magnetron or other microwave generating
device if it is improperly used or connection.
All input and output microwave connections,
waveguide, flange, and gasket must be secure
never operate the device without a microwave
energy absorbing load attached.
Never look into an open waveguide or antenna
while the device is energized.

Gasket

ANTENNA

COOLING FIN

MAGNETRON
CHASSIS GROUND

FILAMENT
TERMINALS

MAGNETRON

INSTALLATIONS

3-1

INSTALLING

1. Empty the microwave oven and clean inside it with
a soft, damp cloth. Check for damage such as
misaligned door, damage around the door or dents
inside the cavity or on the exterior.

2. Put the oven on a counter, table, or shelf that is
strong enough to hold the oven and the food and
utensils you put in it. (The control panel side of the
oven is the heavy side. Use care when handling.)

3. Do not block the vent and the air intake openings.
Blocking vent or air intake openings can cause
damage to the oven and poor cooking results.
Make sure the microwave oven legs are in place to
ensure proper air flow.

4. The oven should not be installed in any area where
heat and steam are generated, because they may
damage the electronic or mechanical parts of the
unit.
Do not install the oven next to a conventional
surface unit or above a conventional wall oven.

5. Use microwave oven in an ambient temperature
less than 104°F(40°C).

6. Place the microwave oven on a sturdy and flat
surface at least 10 cm(4 inches) from the wall.

7. Place the microwave oven as far away as possible
from TV, RADIO, COMPUTER, etc., to prevent
interference.

GROUNDING INSTRUCTIONS

For personal safety, this appliance must be fully
grounded at all times.

In the event of an electrical short circuit, grounding
reduces the risk of electrical shock.
The plug must be plugged into an outlet that is
properly installed and grounded.

BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY.

WARNING

Improper use of the grounding plug can result in a
risk of electric shock.
Do not, under any circumstances, cut or remove
the third ground prong from the power cord plug.

PREFERRED METHOD

ENSURE PROPER GROUND

EXISTS BEFORE USE

10cm

TEMPORARY METHOD
(ADAPTER PLUGS NOT
PERMITTED IN CANADA)

ALIGN LARGE
PRONGS/SLOTS

ENSURE PROPER GROUND
AND FIRM CONNECTION
BEFORE USE

FEATURES

CONTROL PANEL

4-1

OPERATING INSTRUCTIONS

Oven Front Plate

Window Door Screen

Door Seal

Control Panel

Safety Door Lock System

Turntable

Rotating Ring

Display Window

4. CLOCK. Touch this pad to enter the time of day.

5. TIMER. Touch this pad to use your microwave oven as a kitchen

timer.

6. ONE TOUCH POPCORN. Touch this pad to pop a bag of
microwave popcorn without entering a cook power or time.

7. ONE TOUCH POTATO. Touch this pad to cook up to 4 potatoes
without entering a cook power or time.

8. ONE TOUCH BEVERAGE. Touch this pad to heat up to 2 cups
of beverage without entering a cook power or time.

9. ONE TOUCH PIZZA. Touch this pad to heat up to 3 slices of
refrigerated pizza without entering a cook power or time.

10. ONE TOUCH FOOD PLATE. Touch this pad to heat a plate of

food without entering a cook power or time.

11. FROZEN ENTREE. Touch this pad to cook a 10 oz. frozen

entrée without entering a cook power or time.

12. FRESH VEGETABLE. Touch this pad to cook fresh vegetables

without entering a cook power or time.

13. BAKED GOODS. Touch this pad to heat up to

4 items without entering a cook power or time.

14. CASSEROLE. Touch this pad to heat up to 4 cups of casserole

without entering a cook power or time.

15. AUTO DEFROST. Touch this pad to meat, poultry, or fish by

entering a weight.

16.

Ez DEFROST. Touch this pad to thaw only 1lb of food

very quickly.

17. CUSTOM COOK. Touch this pad to set and execute

frequently-used, single-stage cooking programs.

18. NUMBER PADS. Touch number pads to enter cooking time,

power level, quantities, or weights.

19. TIME. Touch this pad to set a cooking time.

20. POWER. Touch this pad to set a cooking power.

21. STOP/CLEAR. Touch this pad to stop the oven or clear

entries.

22. EZ ON. It will add 30 seconds up to 3 minutes 30 seconds;
after 3 minutes 30 seconds, every touch will add 1 minute up
to 99 min 59 seconds.

23. START. Touch this pad to start all entries (except the ONE
TOUCH and EZ ON functions, which start automatically).

1. DISPLAY. The display includes a clock and
indicators that tell you time of day, cooking time settings, and
cooking functions selected.

2. MORE. Each time you touch this pad, you add 10 seconds to the
cooking time.

3. LESS. Each time you touch this pad, you
subtract 10 seconds from the cooking time.

1

4

2

3

6

9

12

15

18

21
22

5

7

8
10
11

13
14

16
17

19

20

23

OPERATING SEQUENCE

4-2

The following is a description of component functions
during oven operation.

1. SETTING THE CLOCK

ex.) To set 4:30, touch number key [4],[3], and [0].

NOTE: 1) This is a 12 hour clock.

2) Clock will operate as long as power is
applied to the oven.

2. CANCEL FUNCTION

Touch the pad whenever you need to
cancel an entry or a function currently in use.
The display will either return to the last item entered
or to the clock.

3. EZ ON

4. ONE TOUCH CONTROL

NOTE: Heat only 1 package at a time

5. TIME COOKING

6. MULTI-STAGE COOKING

7. AUTO DEFROST COOKING

9. CHILD LOCK

This oven has a CHILD LOCK feature

TO SET CHILD LOCK

Touch the pad

Touch and hold pad LOCK appear
on the display.

TO CANCEL CHILD LOCK

Touch the pad

Touch and hold pad

LOCK

disappears on the display.

10. MORE / LESS

The cook time is adjustable by MORE pad or LESS
pad

11. CUSTOM COOK

You can program the cook time and power level by
using CUSTOM COOK pad.
ex) To set cook time 10 mine 30seconds, touch

number key [1],[0],[3], and [0]

You can program your oven to switch from one power
level to another for up to 3 stages.

STOP/CLEAR CLOCK

NUMBER

STOP/CLEAR

POPCORN

NUMBER OF

CATEGORY

NUMBER OF

CATEGORY

STOP/CLEAR

STOP/CLEAR

EZ On

STOP/CLEAR

COOKING

MORE

STOP/CLEAR COOKING

LESS

STOP/CLEAR

1ST STAGE

CLOCK

STOP/

CLEAR

AUTO

DEFROST

NUMBER

OF WEIGHT

START

8. EZ DEFROST

EZ

DEFROST

STOP/CLEAR

CUSTOM

COOK

NUMBER POWER

NUMBER

START

STOP/CLEAR

TIME

NUMBER

POWER

NUMBER START

STOP/CLEAR

TIME

NUMBER POWER

NUMBER

2ND STAGE

TIME

NUMBER

POWER

NUMBER

START

STOP/CLEAR

START

START

STOP/CLEAR

To set a 2-stage cook cycle.

4-3

IMPORTANT SAFETY NOTE: THE SHADED AREAS ON THIS SCHEMATIC DIAGRAM INCORPORATE SPECIAL FEATURES

IMPORTANT FOR PROTECTION FROM MICROWAVE RADIATION, FIRE, ELECTRICAL SHOCK, AND

HAZARDS. WHEN SERVICING IT IS ESSENTIAL THAT ONLY MANUFACTURER’S SPECIFIED PARTS

BE USED FOR THE CRITICAL COMPONENTS IN THE SHADED AREAS OF THE SCHEMATIC DIAGRAM.

NOTICE: SINCE THIS IS BASIC SCHEMATIC DIAGRAM, THE VALUES OF COMPONENTS AND

SOME PARTIAL CONNECTIONS ARE SUBJECT TO CHANGE FOR IMPROVEMENT.

SCHEMATIC DIAGRAM

4-4

CIRCUIT DESCRIPTION

GENERAL DETAILS

• The low voltage transformer supplies the necessary
voltage to the micom controller when power cord is
plugged in.

• When the door is closed, the primary switch is ON, the

secondary switch is ON, and the monitor switch opens
(contact COM and NO).

WHEN SELECTING COOKING POWER
LEVEL AND TIME

• The micom controller memorizes the function you set.

• The time you set appears in the display window.

• Each indicator light turns on to indicate that the stage

has been set.

WHEN TOUCHING THE START PAD

• The coil of the relay is energized by the micom

controller.

• Power input is supplied to the high voltage transformer

through the fuse to the primary switch and relay 2.

• Turntable rotates.

• The fan motor rotates and cools the magnetron by

blowing the air (coming from the intake on the base­plate).

• The air is also directed into the oven to exhaust the

vapor in the oven through the upper plate.

• Cooking time starts counting down.

• 3.3 volts AC is generated from the filament winding of

the high voltage transformer. This 3.3 volts is applied to
the magnetron to heat the magnetron filament through
two noise-preventing choke coils.

• A high voltage of approximately 2100 volts AC is
generated in the secondary of the high voltage
transformer which is increased by the action of the high
voltage diode and charging of the high voltage
capacitor.

• The negative 4,000 Volts DC is applied to the filament
of the magnetron.

WHEN THE OVEN IS SET AT ANY LEVEL
EXCEPT MAXIMUM.

• The micom controller controls the ON-OFF time of
relay 2 by the applied signal to vary the average output
power of microwave oven as POWER LEVEL.
(refer to page 1-1)

• One complete cycle of relay 2 is 22 seconds.

WHEN THE DOOR IS OPENED DURING
COOKING

• Both the primary switch and relay 2 cut off the primary
winding voltage of the high voltage transformer.

• ON-OFF of relay 2 is coupled electrically with opening
and closing of the secondary switch.

• When the door is opened, the secondary switch is
opened and when the door is closed, the secondary
switch is closed.

• The cooking time stops counting down.

• Relay stops functioning.

• As the door is opened, if the contact of primary switch
and relay2 and/or secondary switch fail to open, the
fuse opens due to the large current surge caused by
the monitor switch activation, which in turn stops
magnetron oscillation.

L

FUSE

H.V.

TRANS-

FORMER

RELAY 2

MICOM CONTROLLER

SECONDARY
SWITCH

PRIMARY

SWITCH

MONITOR

SWITCH

N

L

FUSE

N

L

L

PRIMARY

SWITCH

RELAY 2

MICOM CONTROLLER

MONITOR

SWITCH

H.V.

TRANS-

FORMER

SECONDARY
SWITCH

5-1

CAUTIONS

• Be sure to check microwave leakage prior to
servicing the oven if the oven is operative prior to
servicing.

• The service personnel should inform the
manufacture importer, or assembler of any certified
oven unit found to have a microwave emission
level in excess of 5 mW/cm2and should repair any

unit found to have excessive emission levels at no cost
to the owner and should ascertain the cause of the
excessive leakage. The service personnel should
instruct the owner not to use the unit until the oven has
been brought into compliance.

• If the oven operates with the door open, the service
personnel should:

- Tell the user not to operate the oven.

- Contact the manufacturer.

• The service personnel should check all surface and
vent openings for microwave leakage.

• Check for microwave leakage after every servicing. The
power density of the microwave radiation leakage
emitted by the microwave oven should not exceed
4 mW/cm2. Always start measuring of an unknown field
to assure safety for operating personnel from radiation
leakage.

MEASURING MICROWAVE ENERGY
LEAKAGE

• Pour 275±15cc of 20±5°C(68±9°F) water in a beaker
which is graduated to 600 cc, and place the beaker
on the center of the turntable.

• Set the energy leakage monitor to 2,450 MHz and
use it following the manufacturer's recommended
test procedure to assure correct result.

• When measuring the leakage, always use the 2-inch
(5cm) spacer supplied with the probe.

• Operate the oven at its maximum output.

• Measure the microwave radiation using and

electromagnetic radiation monitor by holding the
probe perpendicular to the surface being measured

Move probe along shaded area

Probe scanning speed
Less than 2.5 cm/sec
( 1in/sec)

SERVICE INFORMATION

TOOLS AND MEASURING INSTRUMENTS

MICROWAVE LEAKAGE TEST

NECESSARY TOOLS

Tools normally used for TV servicing are sufficient.
Standard tools are listed below.

• Diagonal pliers

• Long nose pliers

• Phillips screwdriver

• Flat blade screwdriver

• Wrench (size 5mm)

• Nutdriver (size 5mm)

• Adjustable wrench

• Soldering iron

• Solder

• Vinyl insulation tape

• Polishing cloth

NECESSARY MEASURING INSTRUMENTS

• TESTER (VOLTS-DC, AC, Ohmmeter)

• Microwave survey meter

- Holaday HI-1500
HI-1501

- Narda 8100

8200

• Inch scale

• 600 cc non conductive material beaker (glass or plastic),
inside diameter: approx. 8.5 cm (3

1

/2

in.)

• Cylindrical and made of borosilicate glass vessel.
max. thickness: 3 mm
outside diameter: approx. 190mm
height: approx. 90mm

• Glass thermometer: 100°C or 212°F (1 deg scale)