Frigidaire GLBM188HB, GLBM188HS, PLBMV188HC Service Manual

Page 1

OVER THE RANGE MICROWAVE OVEN

SERVICE MANUAL

Models GLBM188HB

GLBM188HS PLBMV188HC

This service manual is intended for use by persons having electrical and mechanical training and a level of knowledge of these subjects generally considered acceptable in the appliance repair trade. Electrolux Home Products cannot be responsible, nor assume any liability, for injury or damage of any kind arising from the use of this manual.

! ATTENTION !

Part # 316439268Publication # 5995526885 October 2008

Page 2

CONTENTS

SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

CHAPTER 1

WARNING TO SERVICE PERSONNEL. . . . . . . . . . . . . . . . . . . . . 4

[1] Before Servicing [2] When Testing Is Completed [3] After Repairing

CHAPTER 2.

MICROWAVE MEASUREMENT PROCEDURE. . . . . . . . . . . . . . 5

[1] Requirements [2] Preparation For Testing [3] Leakage Test CHAPTER 3.

FOREWORD AND WARNING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

[1] Foreword [2] Warning [3] Danger CHAPTER 4.

PRODUCT DESCRIPTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

 [1]Specications

CHAPTER 5.

GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

[1] Grounding Instructions pg. 8 [2] Oven Diagram pg. 8 [3] Control Panel pg. 9 CHAPTER 6.

OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

[1] Description Of Operating Sequence Off Condition pg. 10 Cooking Condition pg. 10 Power Level pg. 10 Power Output Reduction pg. 10 Ventilation Methods pg. 10 Sensor Cooking Condition pg. 11 Cooking Sequence pg. 11 [2] Oven Schematic pg. 12 [3] Description And Function Of Components Door Open Mechanism pg. 13 Door Sensing Switch pg. 13 Secondary Interlock Switch pg. 13 Monitor Switch pg. 13 Cavity Thermal Cut Out pg. 13 Turntable Motor pg. 13 Cooling Fan Motor pg. 13 Hood Fan Motor pg. 13 Thermostat [60° C ON] pg. 13 Antenna [Stirrer] Motor pg. 13 Cook Top Lamp pg. 13 CHAPTER 7.

TROUBLESHOOTING GUIDE. . . . . . . . . . . . . . . . . . . . . . . . . . 14

[1] Troubleshooting Chart pg. 15 CHAPTER 8.

TEST PROCEDURES. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 16

[1] Magnetron Assembly Test pg. 16 [2] Power Transformer Test pg. 16

 [3]HighVoltageRectierTest  pg.16

[4] High Voltage Capacitor Test pg. 17 [5] Thermal Cutout and Temperature Fuse Test pg. 17 [6] Secondary Interlock Switch Test pg. 17 [7] Primary Interlock System Test pg. 18 [8] Monitor Switch Test pg. 18 [9] Blown Monitor Fuse Test pg. 18 [10] Hood Thermostat Test pg. 19 [11] Hood Fan Motor Test pg. 19 [12] Touch Control Panel Assembly Test pg. 19 [13] Key Unit Test pg. 21 [14] Relay Test pg. 21 [15] Open PWB Fuse Procedures pg. 22 [16] Humidity Sensor Test pg. 22 [17] Noise Filter Test pg. 24

CHAPTER 9.

TOUCH CONTROL PANEL ASSEMBLY. . . . . . . .. . . . . . . 25

[1] Outline Of Touch Control Panel Assy. pg. 25 [2] Humidity Sensor Circuit pg. 26 [3] Servicing For Touch Control Panel pg. 27 CHAPTER 10.

PRECAUTIONS FOR USING LEADFREE SOLDER . . . . . . . . . . . 28

CHAPTER 11. COMPONENT REPLACEMENT AND

ADJUSTMENT PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

[1] Warnings pg. 29 [2] Adjustments With Oven Installed pg. 29 [3] Removal Of Oven From Wall pg. 29 [4] Hood Louver Removal pg. 30 [5] Outer Case Removal pg. 30 [6] Power Transformer Removal pg. 30 [7] Hood Fan Motor, Hood Duct Oven Lamp Socket, and Humidity Sensor Removal pg. 30 [8] Magnetron Removal pg. 31

 [9]HighVoltageRectierand

Capacitor Removal pg. 31 [10] Hood Fan Thermostat Removal pg. 32 [11] Cooling Fan Removal pg. 32 [12] Turntable Motor Removal pg. 33 [13] Antenna (Stirrer) Motor Removal pg. 33 [14] Stirrer Cover and Antenna Installation pg. 33 [15] Oven Lamp Removal pg. 33 [16] Positive Lock Connector Removal pg. 33 [17] Right Panel Assembly and Power Unit Removal pg. 33 [18] Door Switch Removal pg. 34 [19] Door Switch Adjustment pg. 34 [20] Door Replacement pg. 34 [21] Door Disassembly pg. 35 [22] Cooktop Lamp Socket Removal pg. 36

CHAPTER 12.

CIRCUIT DIAGRAMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

[1] Pictorial Diagram pg. 37 [2] Power Unit Circuit pg. 38 [3] Keypad Unit and Display Circuit pg. 39 [4] Printed Wiring Board (PWB) pg. 40

PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Page 2

Page 3

GLBM188HB

ServiceManual



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.

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 Federal Performance Standard should be

performed on each oven prior to release to the owner.

Before servicing an operative unit, perform a microwave emission check as per the Microwave Measurement Procedure outlined in this service manual. If microwave emissions level is in excess of the specified limit, contact ELECTROLUX HOME PRODUCTS, INC. immediately.

If the unit operates with the door open, service person should 1) tell the user not to operate the oven and 2) contact ELECTROLUX HOME PRODUCTS, INC. and Food and Drug Administration's Center for Devices and Radiological Health immediately.

Service personnel should inform ELECTROLUX HOME PRODUCTS, INC. of any certified unit found with emissions in excess of 4mW/cm . The owner of the unit should be instructed not to use the unit until the oven has been brought into compliance.

BEFORE SERVICING

Page 3

Page 4

GLBM188HB

ServiceManual



CHAPTER 1. WARNING TO SERVICE PERSONNEL

Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts may result in a severe, possibly fatal, electrical shock.

(Example)

High Voltage Capacitor, High Voltage Power Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness etc..

Read the Service Manual carefully and follow all instructions.

[1] Before Servicing

1. Disconnect the power supply cord , and then remove outer case.

2. Open the door and block it open.

3. Discharge high voltage capacitor.

WARNING: RISK OF ELECTRIC SHOCK. DISCHARGE THE HIGH-

VOLTAGE CAPACITOR BEFORE SERVICING.

The high-voltage capacitor remains charged about 60 seconds after the oven has been switched off. Wait for 60 seconds and then shortcircuit the connection of the high-voltage capacitor (that is the connecting lead of the high-voltage rectifier) against the chassis with the use of an insulated screwdriver.

Whenever troubleshooting is performed the power supply must be disconnected. It may, in some cases, be necessary to connect the power supply 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.

4) Disconnect the leads to the primary of the power transformer.

5) Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.

6) After that procedure, reconnect the power supply cord.

[2] 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.

[3] After repairing

1. Reconnect all leads removed from components during testing.

2. Reinstall the outer case (cabinet).

3. Reconnect the power supply cord after the outer case is installed.

4. Run the oven and check all functions.

Microwave ovens should not be run empty. To test for the presence of microwave energy within a cavity, place a cup of cold water on the oven turntable, close the door and set the power to HIGH and set the microwave timer for two (2) minutes. When the two minutes has elapsed (timer at zero) carefully check that the water is now hot. If the water remains cold carry out Before Servicing procedure and reexamine the connections to the component being tested.

When all service work is completed and the oven is fully assembled, the microwave power output should be checked and microwave leakage test should be carried out.

Don't Touch ! Danger High Voltage

Page 4

Page 5

GLBM188HB

ServiceManual



CHAPTER 2. MICROWAVE MEASUREMENT PROCEDURE

[1] Requirements:

1. Microwave leakage limit (Power density limit):

Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven should not exceed 1mW/ cm2 at any point 5cm or more from the external surface of the oven, measured prior to acquisition by a purchaser, and thereafter (through the useful life of the oven), 5 mW/cm

at any point 5cm or more from the external surface of the oven.

2. Safety interlock switches:

Primary interlock relay and door sensing switch shall prevent microwave radiation emission in excess of the requirement as above mentioned. Secondary interlock switch shall prevent microwave radiation emission in excess of 5 mW/cm

at any point 5cm or more from the external surface

of the oven.

[2] Preparation for testing:

Before beginning the actual measurement of leakage, proceed as follows:

1. Make sure that the actual instrument is operating normally as specified in its instruction booklet.

Important:

Survey instruments that comply with the requirement for instrumentation as prescribed by the performance standard for microwave ovens, 21 CFR

1030.10(c)(3)(i), must be used for testing.

2. Place the oven tray in the oven cavity.

3. Place the load of 275±15 ml (9.8 oz) of tap water initially at 20±5°C (68°F) in the center of the oven cavity.

The water container shall be a low form of 600 ml (20 oz) beaker with an inside diameter of approx. 8.5 cm (3-1/2 in.) and made of an electrically nonconductive material such as glass or plastic.

The placing of this standard load in the oven is important not only to protect the oven, but also to insure that any leakage is measured accurately.

4. Set the cooking control on Full Power Cooking Mode.

5. Close the door and select a cook cycle of several minutes. If the water begins to boil before the survey is completed, replace it with 275 ml of cool water.

[3] Leakage test:

Closed-door leakage test (microwave measurement):

1. Grasp the probe of the survey instrument and hold it perpendicular to the gap between the door and the body of the oven.

2. Move the probe slowly, not faster than 1 in./sec. (2.5 cm/sec.) along the gap, watching for the maximum indication on the meter.

3. Check for leakage at the door screen, sheet metal seams and other accessible positions where the continuity of the metal has been breached (eg., around the switches, indicator, and vents).

While testing for leakage around the door, pull the door away from the front of the oven as far as is permitted by the closed latch assembly.

4. Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater than 4mW/cm

NOTE: After servicing, record data on service invoice and microwave leakage report.

Page 5

Page 6

GLBM188HB

ServiceManual



CHAPTER 3. FOREWORD AND WARNING

[1] FOREWORD

This Manual has been prepared to provide Electrolux Home Products Service Personnel with Operation and Service Information for the ELECTROLUX OVER THE RANGE MICROWAVE OVENS, PLBMV188HC, GLBM188HS and GLBM188HB.

It is recommended that service personnel carefully study the entire text of this manual so that they will be qualified to render satisfactory customer service.

Check the interlock switches and the door seal carefully. Special attention should be given to avoid electrical shock and microwave radiation hazard.

[2] WARNING

Never operate the oven until the following points are ensured.

(A) The door is tightly closed.

(B) The door brackets and hinges are not defective.

(D) The door is not deformed or warped.

(E) There is not any other visible damage with the oven.

Servicing and repair work must be carried out only by trained service personnel.

[3] DANGER

Certain initial parts are intentionally not grounded and present a risk of electrical shock only during servicing. Service personnel - Do not contact the following parts while the appliance is energized;

High Voltage Capacitor, Power Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness;

If provided, Vent Hood, Fan assembly, Cooling Fan Motor.

All the parts marked “ “on parts list are used at voltages more than 250V.

Removal of the outer wrap gives access to voltage above 250V.

All the parts marked “*“on parts list may cause undue microwave exposure, by themselves, or when they are damaged, loosened or removed.

Page 6

Page 7

GLBM188HB

ServiceManual



CHAPTER 4. PRODUCT DESCRIPTION

[1] SPECIFICATIONS

ITEM DESCRIPTION

Power Requirements

120 Volts / 14.3 Amperes 60 Hertz Single phase, 3 wire grounded

Power Output

1000 W nominal of RF microwave energy (IEC Test procedure) Operating frequency of 2450 MHz

Case Dimensions

Width 29 15/16" Height 17 1/16" Depth 18 15/32" (Not including the door handle)

Cooking Cavity Dimensions (1.8 Cubic feet)

Width 22 1/2" NOTE: Internal capacity is calculated by measuring maximum width, depth and height. Height 10 1/16" Actual capacity for holding food is less.

Depth 14 31/32" Hood lamp 20W x 2 incandescent Hood fan Approx. 300 C.F.M.

Control Complement

Touch Control System

Clock (1:00 - 12:59)

Timer (0 - 99 minutes 99 seconds)

Microwave Power for Variable Cooking

Repetition Rate;

Full power throughout the cooking time

Approx. 90% of FULL Power

Approx. 80% of FULL Power

Approx. 70% of FULL Power

Approx. 60% of FULL Power

Approx. 50% of FULL Power

Approx. 40% of FULL Power

Approx. 30% of FULL Power

Approx. 20% of FULL Power

Approx. 10% of FULL Power

No power throughout the cooking time

Light Hi/Lo/Off pad

Vent Hi/Lo/Off pad

Sensor Cook pad

Sensor Reheat pad

Auto Cook pad

Auto Defrost pad

Timer on-off pad

User Pref pad

Keep Warm pad

Melt Soften pad

Snacks Menu pad

Popcorn pad

Veggies pad

Baked Potato pad

Power level pad

Turntable on-off pad

STOP/Clear pad

START/Enter pad

Add 30 Sec pad

Number pads

(Quick start pads) Oven Cavity Light 20W x 1 incandescent light bulb

Safety Standard

UL Listed.

FCC Authorized

DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J Weight Approx. 61 lbs.

Page 7

Page 8

GLBM188HB

ServiceManual



CHAPTER 5. GENERAL INFORMATION

[1] GROUNDING INSTRUCTIONS

This oven is equipped with a three prong grounding plug. It must be plugged into a wall receptacle that is properly installed and grounded in accordance with the National Electrical Code and local codes and ordinances.

In the event of an electrical short circuit, grounding reduces the risk of electric shock by providing an escape wire for the electric current.

WARNING:

Improper use of the grounding plug can result in a risk of electric shock.

Electrical Requirements

The oven is equipped with a 3-prong grounding plug. DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE GROUNDING PIN FROM THE PLUG.

The power supply cord and plug must be connected to a separate 120 Volt AC, 60 Hz, 15 Amp. or more dedicated line, using a grounded receptacle. The receptacle should be located inside the cabinet directly above the Microwave Oven/Hood system mounting location.

[2] OVEN DIAGRAM

1. OVEN

1. Microwave oven door with see-through window

2. Door hinges

3. Waveguide cover: DO NOT REMOVE.

4. Turntable motor shaft

5. Microwave oven light

It will light when microwave oven is operating or door is open.

6. Rack holders

7. Safety door latches

The microwave oven will not operate unless the door is securely closed.

8. Handle

9. Light Hi/Lo/Off pad

Press the Light Hi/Lo/Off pad once for high, twice for low and three times to turn off the light.

10.Vent Hi/Lo/Off pad

Press the Vent Hi/Lo/Off pad once for high speed, twice for low speed and three times to turn off the fun.

11.Control panel

12.Time display: Digital display, 99 minutes, 99 seconds

13.Ventilation openings

14.Removable turntable

The turntable will rotate clockwise or counterclockwise.

Only remove for cleaning.

15.Removable turntable support

First, carefully place the turntable support in the motor shaft in the center of the microwave oven floor. Then, place the turntable on the turntable support securely.

16.Rack for 2-level cooking/ reheating

17.Light cover

18.Grease filters

19.Menu label

3-Pronged Plug

Grounded Receptacle Box

Grounding Pin

3-Pronged Receptacle

BOTTOM VIEW

FRONT VIEW

(Front of microwave oven)

(Rear of microwave oven)

5 7

9 10

Page 8

Page 9

5 – 2

[3] CONTROL PANEL

Page 9

Page 10

GLBM188HB

ServiceManual



CHAPTER 6. OPERATION

[1] DESCRIPTION OF OPERATING SEQUENCE

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

1. OFF CONDITION

Closing the door activates the door sensing switch and secondary interlock switch. (In this condition, the monitor switch contacts are opened.)

When oven is plugged in, 120 volts A.C. is supplied to the control unit. (Figure O-1).

1. The display will show “ENJOY YOUR OVEN PRESS CLEAR”.

To set any program or set the clock, you must first touch the Clear

Off pad. The display will clear, and “ : " will appear

2. COOKING CONDITION

Program desired cooking time touching the NUMBER pads. When the START pad is touched, the following operations occur:

1. The contacts of relays are closed and components connected to the relays are turned on as follows.

(For details, refer to Figure O-2)

2. 120 volts A.C. is supplied to the primary winding of the power transformer and is converted to about 3.3 volts A.C. output on the filament winding, and approximately 2000 volts A.C. on the high voltage winding.

3. The filament winding voltage heats the magnetron filament and the H.V. winding voltage is sent to a voltage doubler circuit.

4. The microwave energy produced by the magnetron is channelled through the waveguide into the cavity feed box, and then into the cavity where the food is placed to be cooked.

5. Upon completion of the cooking time, the power transformer, oven lamp, etc. are turned off, and the generation of microwave energy is stopped. The oven will revert to the OFF condition.

6. When the door is opened during a cook cycle, monitor switch, door sensing switch, secondary interlock switch, and primary interlock relay are activated with the following results. The circuits to the antenna motor, the cooling fan motor, the turntable motor, and the high voltage components are de-energized, and the digital read-out displays the time still remaining in the cook cycle when the door was opened.

7. The monitor switch is electrically monitoring the operation of the secondary interlock switch and door sensing switch is mechanically associated with the door so that it will function in the following sequence.

1) When the door opens from a closed position, the primary inter-

lock relay, door sensing switch and secondary interlock switch open their contacts, and then the monitor switch contacts close.

2) When the door is closed from the open position, the monitor

switch contacts open first. Then the contacts of the secondary interlock switch and door sensing switch close. And contacts of the relay (RY1) open.

If the secondary interlock switch and primary interlock relay (RY2) fail with the contacts closed when the door is opened, the closing of the monitor switch contacts will form a short circuit through the monitor fuse, secondary interlock switch, relay (RY1) and primary interlock relay (RY2), causing the monitor fuse to blow.

3. POWER LEVEL P-0 to P-90 COOKING

When Variable Cooking Power is programmed, the 120 volts A.C. is

supplied to the power transformer intermittently through the contacts of relay (RY2) which is operated by the control unit within an interval sec-

ond time base. Microwave power operation is as follows:

NOTE: The ON/OFF time ratio does not correspond with the percent-

age of microwave power, because Approx. 2 seconds are needed for heating of the magnetron filament.

4. POWER OUTPUT REDUCTION

If the oven is set for over 40 minutes at 80%, 90% or 100% power level, after the first 40 minutes the power level will automatically adjust itself to 70% power to avoid overcooking.

5. VENTILATION METHODS HOT AIR EXHAUST

1. VERTICAL VENTING

For this venting method, hot air rising from the conventional range below is drawn in by the hood fan motor through the grease filters at the right and left sides of the base cover, up through the right and left sides of the oven cavity, then discharged vertically at rear center top of the oven, into the customer's vent system.

RELAY CONNECTED COMPONENTS

RY1 Oven lamp / Fan motor / Antenna motor RY2 Power transformer

RY3 Turntable motor

VARI-MODE ON TIME OFF TIME

100% power 32 sec. 0 sec. Approx. 90% power 30 sec. 2 sec. Approx. 80% power 26 sec. 6 sec. Approx. 70% power 24 sec. 8 sec. Approx. 60% power 22 sec. 10 sec. Approx. 50% power 18 sec. 14 sec. Approx. 40% power 16 sec. 16 sec. Approx. 30% power 12 sec. 20 sec. Approx. 20% power 8 sec. 24 sec. Approx. 10% power 6 sec. 26 sec. 0% power 0 sec. 32 sec.

HOOD FANMOTOR

AIR FLOW

HOOD INTAKE DUCT

TO DUCT

GREASE FILTER

Page 10

Page 11

GLBM188HB

2. HORIZONTAL VENTING

The air handing is the same as VERTICAL VENTING except that the final air discharge is directed horizontally out from the top rear of the oven into the customer's vent system.

3. RE-CIRCULATION (INSIDE VENTING)

The air handing is the same as VERTICAL VENTING except that the final air discharge is directed horizontally through the upper front of the oven into the kitchen. In this case, the charcoal filter must be used which have already been installed in the oven.

6. SENSOR COOKING CONDITION

Using the SENSOR function, food is cooked without figuring time, power level or quantity. When the oven senses enough steam from the food, it relays the information to its microprocessor which will calculate the remaining cooking time and power level needed for best results. When the food is cooked, water vapor is developed. the sensor “senses” the vapor and its resistance increase gradually. When the resistance reaches the value set according to the menu, supplementary cooking is started. The time of supplementary cooking is determined by experiment with each food category and inputted into the LSI. An example of how sensor works: (Potatoes)

1. Potatoes at room temperature. Vapor is emitted very slowly.

2. Heat Potatoes. Moisture and humidity is emitted very rapidly. You

can smell the aroma as it cooks.

6.1. Cooking Sequence.

1. Operate the oven in sensor cooking mode by referring to the operation manual.

NOTE: The oven should not be operated on Sensor Cooking immedi-

ately after plugging in the unit. Wait two minutes before cooking on Sensor Cooking.

2. The coil of shut-off relays (RY1 and RY3) are energized, the oven lamp, turntable motor and cooling fan motor are turned on, but the power transformer is not turned on.

3. After about 32 seconds, the relay (RY2) is energized.

The power transformer is turned on, microwave energy is produced and first stage is started.

The 32 seconds is the cooling time required to remove any vapor from the oven cavity and sensor.

NOTE: During this first stage, do not open the door or touch Clear Off

pad.

4. When the sensor detects the vapor emitted from the food, the display switches over to the remaining cooking time and the timer counts down to zero.

At this time, the door may be opened to stir food, turn it or season, etc.

5. When the timer reaches zero, an audible signal sounds.The shutoff relay (RY1 and RY3) and relay (RY2) are generalized and the power transformer, oven lamp, etc. are turned off.

6. Opening the door or touching the STOP CLEAR pad, the time of day will reappear on the display and the oven will revert to an OFF condition.

HOOD FANMOTOR

AIR FLOW

HOOD INTAKE DUCT

TO DUCT

GREASE FILTER

HOOD FANMOTOR

AIR FLOW

HOODEXHAUST LOUVER

CHARCOAL FILTER

HOOD INTAKE DUCT

IC R OW AV E

MICROWAVE

HUMIDITY SENSOR

Page 11

Page 12

GLBM188HB

[2] OVEN SCHEMATIC

Figure O-1. Oven Schematic-Off Condition

Figure O-2. Oven Schematic-Cooking Condition

SCHEMATIC

NOTE: CONDITION OF OVEN

1. DOOR CLOSED

2. CLOCK APPEARS ON DISPLAY

SCHEMATIC

NOTE: CONDITION OF OVEN

1. DOOR CLOSED.

2. COOKING TIME PROGRAMMED.

3. VARIABLE COOKING CONTROL "P-HI".

4. START PAD TOUCHED.

NOTE: " " indicates components with potentials above 250

BLK

RED

MAGNETRON TEMP.FUSE

WHT

6 3 2 4 5 1

RY5

HOOD FAN MOTOR

WHT

RY6

RY7

BLK

WHT

BRN

WHT

N. O.

OVEN LAMP RELAY

COM.

GRY

CONTROL UNIT

DOOR UNIT

WHT

ANTENNA

MOTOR

YLW

WHT

YLW

RED

N.C

RED

WHT

D40

20W

RED

GRN

DOOR SENSING

SWITCH

WHT

RY1

BRN

VRS1

RY8

HUMIDITY SENSOR

BLK

PRIMARY INTERLOCK RELAY

LOW VOLTAGE TRANSFORMER

RY2

COM.

N.O.

BLK B

BRN

RY3

TURNTABLE MOTOR RELAY

CN-L

CN-J

CN-G

FAN

MOTOR

WHT

YLW

GRY

WHT

MONITOR

SWITCH

WHT

GRY

SECONDARY INTERLOCK SWITCH

OVEN LAMP

20W

TURNTABLE

MOTOR

TTM

ATM

COM.

HIGH VOLTAGE RECTIFIER

HIGH VOLTAGE CAPACITOR

0.94uF 2300VAC

POWER TRANSFORMER

NOTES:

1. Circuits subject to change without notice

2. The neutral wire(White or Gray wire) must be connected to the prescribed tab terminal of the lamp socket.

3. Only certain models use the humidity sensor.

4. The neutral wire(White/Gray wire) must be connected to the winding end tab terminal of the power transformer primary winding.

5. Only PLBMZ189HC has the earth wire.

MAGNETRON

POWER UNIT

145ºC

60ºC

120ºC

150ºC

OVEN THERMAL CUT OUT

HOOD FAN THERMOSTAT

High

Low

COOK TOP LAMP

N.O.

*NOTE 2

*NOTE 3

*NOTE 2

*NOTE 5

*NOTE 4

GRN

CN-M

CN-N

CN-D

GND

120V AC 60Hz

COM

N.O.

RED

YLW

BLK BLK

PPL

BLK

WHT WHT

NOISE SUPRESSION COIL 1.0mH

LINE BYPASS CAPACITOR

3300pF 250V

FUSE

20A

LINE BYPASS CAPACITOR

3300pF 250V

NOISE FILTER UNIT

RED

BLK

GRY

ORG

SWITCH UNIT

BLK

RED

MAGNETRON TEMP.FUSE

WHT

6 3 2 4 5 1

RY5

HOOD FAN MOTOR

WHT

RY6

RY7

BLK

WHT

BRN

WHT

N. O.

OVEN LAMP RELAY

COM.

GRY

CONTROL UNIT

DOOR UNIT

WHT

ANTENNA

MOTOR

YLW

WHT

YLW

RED

N.C.

RED

WHT

D40

20W

RED

GRN

DOOR SENSING

SWITCH

WHT

RY1

BRN

RED RE

VRS1

RY8

HUMIDITY SENSOR

BLK

PRIMARY INTERLOCK RELAY

LOW VOLTAGE TRANSFORMER

RY2

COM.

N.O.

BLK BLK

BRN

RY3

TURNTABLE MOTOR RELAY

CN-L

CN-J

CN-G

FAN

MOTOR

WHT

YLW

GRY

WHT

MONITOR

SWITCH

WHT

GRY

SECONDARY INTERLOCK SWITCH

OVEN LAMP

20W

TURNTABLE

MOTOR

TTM

ATM

COM.

HIGH VOLTAGE RECTIFIER

HIGH VOLTAGE CAPACITOR

0.94uF 2300VAC

POWER

TRANSFORMER

NOTES:

1. Circuits subject to change without notice

2. The neutral wire(White or Gray wire) must be connected to the prescribed tab terminal of the lamp socket.

3. Only certain models use the humidity sensor.

4. The neutral wire(White/Gray wire) must be connected to the winding end tab terminal of the power transformer primary winding.

5. Only PLBMZ189HC has the earth wire.

MAGNETRON

POWER UNIT

145ºC

60ºC

120ºC

150ºC

OVEN THERMAL CUT OUT

HOOD FAN THERMOSTAT

High

Low

COOK TOP LAMP

N.O.

*NOTE 2

*NOTE 3

*NOTE 2

*NOTE 5

*NOTE 4

GRN

CN-M

CN-N

CN-D

GND

120V AC 60Hz

COM

N.O.

RED

YLW

BLK BLK

PPL

BLK

WHT WHT

NOISE SUPRESSION COIL 1.0mH

LINE BYPASS CAPACITOR

3300pF 250V

FUSE

20A

LINE BYPASS CAPACITOR

3300pF 250V

NOISE FILTER UNIT

RED

BLK

GRY

ORG

SWITCH UNIT

Page 12

Page 13

GLBM188HB

[3] DESCRIPTION AND FUNCTION OF COMPONENTS

1. DOOR OPEN MECHANISM

The door is opened by pulling the door handle, refer to the Figure D-1.

Figure D-1. Door Open Mechanism.

2. DOOR SENSING SWITCH, SECONDARY INTERLOCK SWITCH

The secondary interlock switch is mounted in the lower position of the latch hook, the door sensing switch in the primary interlock system is mounted in the upper position of the latch hook is mounted on upper position of the latch hook. They are activated by the latch heads on the door. When the door is opened, the switches interrupt the circuit to all components. A cook cycle cannot take place until the door is firmly closed thereby activating both interlock switches. The primary interlock system consists of the door sensing switch and primary interlock relay located on the control circuit board.

3. MONITOR SWITCH

The monitor switch is activated (the contacts opened) by the latch head on the door while the door is closed. The switch is intended to render the oven inoperative, by means of blowing the monitor fuse, when the contacts of the primary interlock relay (RY2) and secondary interlock switch fail to open when the door is opened.

Functions:

1. When the door is opened, the monitor switch contact close (to the ON condition) due to their being normally closed. At this time the primary interlock relay (RY2), secondary interlock switch are in the OFF condition (contacts open) due to their being normally open contact switches. And the contacts of relay (RY1) are in the ON condition (contacts close).

2. As the door goes to a closed position, the monitor switch contacts are first opened and then the door sensing switch and the secondary interlock switch contacts close. (On opening the door, each of these switches operate inversely.)

3. If the door is opened, and the primary interlock relay (RY2) and secondary interlock switch contacts fail to open, the monitor fuse blows simultaneously with closing of the monitor switch contacts.

CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE TEST

THE DOOR SENSING SWITCH, PRIMARY INTERLOCK RELAY (RY2), RELAY (RY1), SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH FOR PROPER OPER-

ATION. (REFER TO CHAPTER “TEST PROCEDURE”).

NOTE: MONITOR FUSE AND MONITOR SWITCH ARE REPLACED

AS AN ASSEMBLY.

4. THERMAL CUT-OUT (CAVITY)

This thermal cut-out is located on the top of the oven cavity. It is designed to prevent damage to the oven unit if the food in the oven catches fire due to overheating produced by improper setting of cooking time or failure of control unit. Under normal operation, the thermal cut-out remains closed. However, the thermal cut-out will open at 293°F (145°C) causing the oven to shut down.

5. TURNTABLE MOTOR

The turntable motor rotates the turntable located on the bottom of the oven cavity, so that the foods on the turntable cook evenly during cooking. Turntable will turn in either direction. The turntable motor can be turned off by touching TURNTABLE ON/OFF pad.

6. COOLING FAN MOTOR

The cooling fan motor drives a blade which draws external cool air. This cool air is directed through the air vanes surrounding the magnetron and cools the magnetron. This air is channelled through the oven cavity to remove steam and vapors given off from the heating foods. It is then exhausted through the exhausting air vents at the oven cavity.

7. HOOD FAN MOTOR

The hood fan motor is a two-speed, single-phase, double pole induction type, requiring a hood fan capacitor. It is located outside the upper rear part of the oven cavity, is to remove, from around the oven, hot air rising from the conventional electric or gas range over which it is installed. This air is then expelled either vertically or horizontally through the customer supplied duct system, or discharged back into the kitchen. The automatically operation is medium speed. The manual operation is a three speed (Low/ High).

7.1. THERMOSTAT (60°C ON)

This thermostat is located on the right base plate. It is designed to automatically turn on the hood fan motor whenever the hot air rising from the conventional range below causes the temperature at the thermostat to rise to 140°F (60°C) or higher, thus removing this hot air from around microwave oven. When the temperature around the thermostat drops to 113°F (45°C) or lower, the thermostat shuts off the hood fan motor.

8. ANTENNA MOTOR

The motor drives the stirrer fan to stir the microwave radiation from the waveguide.

9. COOK TOP LAMP

The cook top lamp is mounted at the lamp mounting angle on the base cover. Touch the Light pad once for high, twice for low and four times to turn off the light.

Secondary Interlock Switch

Monitor Switch

Latch Hook

Door

Latch Heads

Door Sensing Switch

Page 13

Page 14

GLBM188HB

ServiceManual



CHAPTER 7. 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, relay (RY1) primary interlock relay (RY2), door sensing switch and secondary interlock switch before replacing the monitor fuse. If the monitor fuse is replaced, the monitor switch must also be replaced. Use part FFS-BA042WRKZ 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.

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.

Page 14

Page 15

GLBM188HB

[1] TROUBLESHOOTING CHART

CK = Check / RE = Rep

lace

POSSIBLE CASE AND

DEFECTIVE PARTS

PROBLEM

TEST PROCEDURE

COND

TION

ONDI

TION

IDLE

NDI

ION

LOW VOL

T AGE

P O WE

R AT O

UTLET

SHORTED IN POWER

OPENED OR SHOR

TE D W

IRING

O D M

O T

O R CAPAC

T O

R O

N PWB

COO

K TOP LAMP

O R SOCKET

T URNT

ABLE

O F

F CO

NDITIO

ANTENNA MOTOR

TURNT

AB LE MOTOR

F A N

M OTOR

OVEN LAM

P OR SO

CKET

FUS

E ON P

.W.B.

RELAY ( RY-5

)

RELAY (

R Y

-7,

R Y

-8)

R E L

(RY-6)

RELAY (

R Y

-3)

RE LAY (RY-2)

RELAY (

R Y

)

KE Y UNIT (

DOO

CONT

ROL UNIT

D F

MOTOR

HOO

D T

HERM

OSTA

T 60º

C ON

M ONITOR FUSE

ONITOR SWITCH

P R IMARY

INTE

R LOCK

S YSTE

SECON

DARY INTERLOCK S

W ITCH

TEMPERATU

RE FU

S E OR THERM

A L CUT-OUT

HIGH VOLTAGE CAPACIT

O R

H.V. RE

CTIFIE

P OW

E R TRA

NSF

O RME

MAGNETRON

NOI

FILTER

SENSO

TION

HU MIDI

T Y S

E NSOR

MICROWAVE

COOKING

CONDITION

Home fuse blows when power cord is plugged into wall receptacle.

Monitor fuse blows when power cord is plugged into wall receptacle.

Display does not illuminate when power cord is first plugged into wall receptacle.

Display does not operate properly when STOP/CLEAR key is touched. (The time of day should appear on the display with beep sound during normal condition.)

Oven lamp does not light with door is opened.

Hood fan motor operates when power cord is first plugged into wall receptacle.

Temperature of oven base seems more than 140ºF (60ºC) because of operation of the range below. But hood fan motor does not turn on automatically. (Normally, food fan motor should be operating at mid speed.)

Cook top lamp does not turn on when LIGHT pad is pressed.

Hood fan motor does not rotate at all with touched VENT pad.

Speed of the hood fan motor does not change when the VENT pad is touched for this function.

Oven lamp does not light in cook cycle. (But it does light when door is opened.)

Fan motor does not operate. (Oven lamp and turntable motor operate.)

Turntable motor does not operate (Oven lamp lights and fan motor 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).

Variable cooking does not operate properly except Cooking Power 100% mode.

Function of AUTO DEFROST does not operate properly.

Antenna motor does not operate. (Other parts operate.)

Oven goes into AUTO DEFROST but food is not defrosted well.

The oven stops and "ERROR" is displayed or does not end during Sensor Cooking condition. (Oven does not shut off after a cup of water is boiling by Sensor Cooking.)

Oven stops at 32 seconds after starting.

Page 15

Page 16

GLBM188HB

ServiceManual



CHAPTER 8. TEST PROCEDURES

[1] A: MAGNETRON ASSEMBLY TEST

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. To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check across the magnetron filament leads should indicate less than 1 ohm.

5. To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament leads and chassis ground. This test should indicate an infinite resistance. If there is little or no resistance the magnetron is grounded and must be replaced.

6. Reconnect all leads removed from components during testing.

7. Reinstall the outer case (cabinet).

8. Reconnect the power supply cord after the outer case is installed.

9. Run the oven and check all functions.

1. MICROWAVE OUTPUT POWER

The following test procedure should be carried out with the microwave oven in a fully assembled condition (outer case fitted).

HIGH VOLTAGES ARE PRESENT DURING THE COOK CYCLE, SO EXTREME CAUTION SHOULD BE OBSERVED.

Power output of the magnetron can be measured by performing a water temperature rise test. This test should only be used if above tests do not indicate a faulty magnetron and there is no defect in the following components or wiring: silicon rectifier, high voltage capacitor and power transformer. This test will require a 16 ounce (453cc) measuring cup and an accurate mercury thermometer or thermocouple type temperature tester. For accurate results, the following procedure must be followed carefully:

1. Fill the measuring cup with 16 oz. (453cc) of tap water and measure the temperature of the water with a thermometer or thermocouple temperature tester. Stir the thermometer or thermocouple through the water until the temperature stabilizes. Record the temperature of the water.

2. Place the cup of water in the oven. Operate oven at 100% POWER selecting more than 60 seconds cook time. Allow the water to heat for 60 seconds, measuring with a stop watch, second hand of a watch or the digital read-out countdown.

3. Remove the cup from the oven and again measure the temperature, making sure to stir the thermometer or thermocouple through the water until the maximum temperature is recorded.

4. Subtract the cold water temperature from the hot water temperature. The normal result should be 29.2 to 54.2°F(16.2 to 30.1°C) rise in temperature. If the water temperatures are accurately measured and tested for the required time period the test results will indicate if the magnetron tube has low power output (low rise in water temperature) which would extend cooking time or high power output (high rise in water temperature) which would reduce cooking time. Because cooking time can be adjusted to compensate for power output, the magnetron tube assembly should be replaced only if the water temperature rise test indicates a power output well beyond the normal limits. The test is only accurate if the power supply line voltage is 120 volts and the oven cavity is clean.

[2] B: POWER TRANSFORMER TEST

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. Disconnect the primary input terminals and measure the resistance of the transformer with an ohmmeter. Check for continuity of the coils with an ohmmeter. On the R x 1 scale, the resistance of the primary coil should be less than 1 ohm and the resistance of the high voltage coil should be approximately 85 ohms; the resistance of the filament coil should be less than 1 ohm.

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

(HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO MEASURE THE FILAMENT AND HIGH VOLTAGE.)

[3] C: HIGH VOLTAGE RECTIFIER TEST

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. Isolate the rectifier from the circuit. Using the highest ohm scale of the meter, read the resistance across the terminals and observe, reverse the leads to the rectifier terminals and observe meter reading. If a short is indicated in both directions, or if an infinite resistance is read in both directions, the rectifier is probably defective and should be replaced.

5. Reconnect all leads removed from components during testing.

Page 16

Page 17

GLBM188HB

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

NOTE: Be sure to use an ohmmeter that will supply a forward bias voltage of more than 6.3 volts.

[4] D: HIGH VOLTAGE CAPACITOR TEST

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. If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads and check for short or open between the terminals using an ohmmeter.

Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate continuity for a short time and should indicate an open circuit once the capacitor is charged. If the above is not the case, check the capacitor with an ohmmeter to see if it is shorted between either of the terminals and case. If it is shorted, replace the capacitor.

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

[5] E: THERMAL CUT-OUT AND TEMPERATURE FUSE TEST

1. CAVITY THERMAL CUT-OUT TEST

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. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the temperature of the thermal cut-out reaches approximately 293°F(145°C). An open thermal cut-out indicates overheating of the oven, exchange the oven thermal cut-out and check inside of oven cavity and for improper setting of cooking time or operation of control unit. Check for restricted air flow through the vent holes of the oven cavity, especially the cooling fan and air guide.

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

2. MAGNETRON TEMPERATURE FUSE TEST

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. A continuity check across the magnetron temperature fuse terminals should indicate a closed circuit unless the temperature of the magnetron temperature fuse reaches approximately 302°F(150°C). An open magnetron temperature fuse indicates overheating of the magnetron. Check for restricted air flow to the magnetron, especially the cooling fan air guide.

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE, REPLACE TEMPERATURE FUSE.

[6] F: SECONDARY INTERLOCK SWITCH TEST

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. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal of the switch. The meter should indicate an open circuit with the door open and a closed circuit with the door closed. If improper operation is indicated, replace the secondary interlock switch.

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

Page 17

Page 18

GLBM188HB

8. Run the oven and check all functions.

[7] G: PRIMARY INTERLOCK SYSTEM TEST

1. DOOR SENSING SWITCH

1. Disconnect the power supply cord, and then remove outer case.

2. Open the door and block it open.

3. Discharge high voltage capacitor.

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

NOTE: NOTE: If the door sensing switch contacts fail in the open position and the door is closed, the cooling fan motor, stirrer motor and oven light

will be activated by RY1.

2. PRIMARY INTERLOCK RELAY (RY2)

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. Disconnect two (2) wire leads from the male tab terminals of the Primary Interlock Relay. Check the state of the relay contacts using a ohmmeter. The relay contacts should be open. If the relay contacts are closed, replace the circuit board entirely or the relay itself.

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

[8] H: MONITOR SWITCH TEST

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. Before performing this test, make sure that the second-

ary interlock switch and the primary interlock relay are

operating properly, according to the above Switch Test

Procedure. Disconnect the wire lead from the monitor

switch (COM) terminal. Check the monitor switch operation by using the ohmmeter as follows. When the door is open, the meter should indicate a closed circuit. When

the monitor switch actuator is pushed by a screw driver through the lower latch hole on the front plate of the oven cavity with the door opened (in this condition the plunger of the monitor switch is pushed in), the meter should indicate an open circuit. If improper operation is indicated, the switch may be defective. After testing the monitor switch, reconnect the wire lead to the monitor switch (COM) terminal and check the continuity of the monitor circuit.

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

[9] I: BLOWN MONITOR FUSE TEST

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. If the monitor fuse is blown when the door is opened, check the secondary interlock switch, primary interlock relay (RY2), relay (RY1) and monitor

switch according to the “TEST PROCEDURE” for those switches before replacing the blown monitor fuse.

CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE, TEST THE SECONDARY INTERLOCK SWITCH, PRIMARY INTERLOCK RELAY,

DOOR SENSING SWITCH AND MONITOR SWITCH FOR PROPER OPERATION.

SCREW DRIVER

Black

White/ Gray

MONITOR SWITCH

SECONDARY INTERLOCK SWITCH

OHMMETER

Page 18

Page 19

GLBM188HB

If the monitor fuse is blown by improper switch operation, the monitor fuse and monitor switch must be replaced with “monitor fuse and monitor

switch assembly” part number FFS-BA042WRKZ, even if the monitor switch operates normally. The monitor fuse and monitor switch assembly is comprised of a 20 ampere fuse and switch.

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

[10] J: HOOD THERMOSTAT TEST

1. THERMOSTAT (60°C ON)

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. A continuity check across the thermal cut-out terminals should indicate an open circuit unless the temperature of the thermal cut-out reaches approximately 140°F(60°C) or more. At that temperature, the contacts will close. The thermal cut-out opens automatically at approximately 113°F(45°C).

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

[11] K: HOOD FAN MOTOR TEST

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. If the motor does not turn, touch the Vent Hi/ Lo/ Off pad once (set hood fan motor power “HIGH”) and check voltage between pins “1” and “2” (Blue and Black wires) of the 6 pin connector. If 120 Volts appear and the hood capacitor is good, replace the hood fan assembly. If 120 Volts does not appear, check the motor circuit. The resistance values of motor terminals are as follows:

5. Reconnect all leads removed from components during testing.

6. Reinstall the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

[12] L: TOUCH CONTROL PANEL ASSEMBLY TEST

The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter and ohmmeter.

In this service manual, the touch control panel assembly is divided into three units, Control Unit (Display unit), Key Unit and Power Unit, and troubleshooting by unit replacement is described according to the symptoms indicated.

Before testing,

1) Disconnect the power supply cord, and then disassemble as per “HOOD LOUVER REMOVAL”, “REMOVAL OF OVEN FROM WALL” and “OUTER CASE REMOVAL”.

2) Open the door and block it open.

3) Discharge high voltage capacitor.

Resistance between;

WHT(1) AND GRY(4) = 0shorted) BLK(2) AND GRY(4) = 32 WHT(1) AND BLK(2) = 32 BLK(2) AND RED(3) = 14 RED(3) AND YLW(6) =11 ORG(5) AND YLW(6) = 6

1 2 3

4 5

REDBLKWHT

YLWORG

GRY

146

HOODFAN CAPACITOR

GRY

ORG

WHT

BLK

RED

YLW

6-PIN CONNECTOR OF HOOD FAN MOTOR

Page 19

Page 20

GLBM188HB

4) Disconnect the leads to the primary of the power transformer.

5) Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.

6) After that procedure, re-connect the power supply cord.

1. Key Unit

1) Check Key unit connection before replacement.

2) Reconnect all leads removed from components during testing.

3) Re-install the covers (outer case cabinet and control unit cover).

4) Reconnect the power supply cord after the covers (outer case cabinet and control unit cover) are installed.

5) Run the oven and check all functions.

The following symptoms indicate a defective key unit.

a) When touching the pads, a certain pad produces no signal at all.

b) When touching a number pad, two figures or more are displayed.

c) When touching the pads, sometimes a pad produces no signal.

If the key unit is defective.

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) Remove the control unit cover.

5) Replace the key unit (FPC + key sheet).

6) Reconnect all leads removed from components during testing.

7) Re-install the covers (outer case cabinet and control unit cover).

8) Reconnect the power supply cord after the covers (outer case cabinet and control unit cover) are installed.

9) Run the oven and check all functions.

2. Control Unit.

The following symptoms indicate a defective control unit. Before replacing the control unit, perform the Key unit test (Procedure M) to determine if control unit is faulty.

1) In connection with indicators

a) At a certain digit, all or some segments do not light up.

b) At a certain digit, brightness is low.

c) Only one indicator does not light.

d) The corresponding segments of all digits do not light up; or they continue to light up.

e) Wrong figure appears.

f) A certain group of indicators do not light up.

g) The figure of all digits flicker.

2) Other possible problems caused by defective control unit.

a) Buzzer does not sound or continues to sound.

b) Clock does not operate properly.

c) Cooking is not possible.

3) Power Unit or Touch Control Transformer

a) Fan motor, stirrer motor, oven lamp or electrical parts do not turn on or do not turn off.

b) Digital display on the control unit does not show anything.

When testing is completed,

1) Disconnect the power supply cord, and then disassemble as per “HOOD LOUVER REMOVAL”, “REMOVAL OF OVEN FROM WALL” and “OUTER CASE REMOVAL”.

2) Open the door and block it open.

3) Discharge high voltage capacitor.

4) Reconnect all leads removed from components during testing.

5) Re-install the covers (outer case cabinet and control unit cover).

6) Reconnect the power supply cord after the covers are installed.

7) Run the oven and check all functions.

Page 20

Page 21

GLBM188HB

[13] KEY UNIT (FPC) TEST

1) Disconnect the power supply cord, and then disassemble

as per “HOOD LOUVER REMOVAL”, “REMOVAL OF OVEN FROM WALL” and “OUTER CASE REMOVAL”.

2) Open the door and block it open.

3) Discharge high voltage capacitor.

4) Disconnect the leads to the primary of the power trans-

former.

5) Remove the control unit cover.

6) Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.

7) After that procedure, re-connect the power supply cord.

8) If the display fails to clear when the Clear Off pad is depressed, first verify the flat ribbon cable is making good

contact, verify that the door sensing switch (stop switch) operates properly; that is the contacts are closed when the door is closed and open when

the door is open. If the door sensing switch (stop switch) is good, disconnect the flat ribbon cable that connects the key unit to the control unit and make sure the door sensing switch is closed (either close the door or short the door sensing switch connector). Use the Key unit matrix indicated

on the control panel schematic and place a jumper wire between the pins that correspond to the Clear Off pad making momentary contact. If the control unit responds by clearing with a beep the key unit (FPC) is faulty and must be replaced. If the control unit does not respond, it is faulty and

must be replaced. If a specific pad does not respond, the above method may be used (after clearing the control unit) to determine if the control unit or key pad is at fault.

9) Disconnect the power supply cord and then remove outer case.

10)Open the door and block it open.

11)Discharge high voltage capacitor.

12)Remove the control unit cover.

13)Reconnect all leads removed from components during testing.

14)Re-install the covers (outer case cabinet and control unit cover).

15)Reconnect the power supply cord after the covers (outer case cabinet and control unit cover) are installed.

16)Run the oven and check all functions.

[14] N: RELAY TEST

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. Disconnect the leads to the primary of the power transformer.

5. Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.

6. After that procedure, re-connect the power supply cord.

7. Remove the outer case and check voltage between Pin No. 1 of the 3 pin connector (A) and the oven side terminal of the relay RY1 on the control unit with an A.C. voltmeter.

The meter should indicate 120 volts, if not check oven circuit.

RY1 and RY2 Relay Test

These relays are operated by D.C. voltage

Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation.

DC. voltage indicated ----------------------------- Defective relay.

DC. voltage not indicated ------------------------ Check diode which is connected to the relay coil. If diode is good, control unit is defective.

8. If any abnormal condition is defected, replace the control unit.

9. Disconnect the power supply cord and then remove outer case.

10.Open the door and block it open.

11.Discharge high voltage capacitor.

RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS

RY1 Approx. 24.0V D.C. Oven lamp / Fan motor / Antenna motor RY2 Approx. 24.0V D.C. Power transformer RY5 Approx. 24.0V D.C. Hood motor (HIGH/LOW selection) RY6 Approx. 24.0V D.C. Hood motor

RY7, RY8 Approx. 24.0V D.C. Cook top lamp (HIGH/LOW selection)

RY3 Approx. 24.0V D.C. Turntable motor

G6G7G8G9G10G11G12G13

Power

Level

User Pref

Baked

Potato

Timer

On-Off

Vent

Hi/Lo/Off

Sensor

Reheat

Auto

Defrost

Keep Warm

Melt

Soften

Light

Hi/Lo/Off

Veggies

Popcorn

Snacks

Auto

Cook

Sensor

Cook

START ENTER

Turn

Table

On/Off

STOP

CLEAR

Add

30 Sec.

Page 21

Page 22

GLBM188HB

12.Reconnect all leads removed from components during testing.

13.Re-install the outer case (cabinet).

14.Reconnect the power supply cord after the outer case is installed.

15.Run the oven and check all functions.

[15] O: PROCEDURES TO BE TAKEN WHEN THE FUSE ON THE PRINTED WIRING BOARD (PWB) IS OPEN.

To protect the electronic circuits, this model is provided with a fuse added to the primary on the PWB.

1. Fuse check and repairs.

1) Disconnect the power supply cord.

2) Remove the covers.

3) Open the door and block it open.

4) Discharge high voltage capacitor.

5) If the Fuse is blown, replace power unit.

6) Make a visual inspection of the varistor. Check for burned damage. If the varistor has been burned, replace the power unit.

7) Examine the touch control transformer with a tester for the presence of layer short-circuit (check the primary coil resistance which is approximately

110Ω±10%). If any abnormal condition is detected, replace the power unit.

8) Reconnect all leads removed from components during testing.

9) Re-install the covers.

10)Reconnect the power supply cord after the covers are installed.

11)Run the oven and check all functions.

2. Follow the troubleshooting guide given below, if indicator does not light up after above check and repairs are finished.

1) Disconnect the power supply cord.

2) Remove the covers.

3) Open the door and block it open.

4) Discharge high voltage capacitor.

5) Disconnect the leads to the primary of the power transformer.

6) Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.

7) After that procedure, re-connect the power supply cord.

8) Follow the troubleshooting guide given below for repair.

9) Disconnect the power supply cord, and then remove the covers.

10)Open the door and block it open.

11)Discharge high voltage capacitor.

12)Reconnect all leads removed from components during testing.

13)Re-install the covers.

14)Reconnect the power supply cord after the covers are installed.

15)Run the oven and check all functions.

[16] P: HUMIDITY SENSOR TEST

Checking the initial sensor cooking condition

WARNING: The oven should be fully assembled before following procedure.

1) The oven should be plugged in at least two minutes before sensor cooking.

2) Room temperature should not exceed 35°C.

3) The unit should not be installed in any area where heat and steam are generated. The unit should not be installed, for example, next to a conven-

tional surface unit. Refer to the “INSTALLATION Instructions”.

4) Exhaust vents are provided on the back of the unit for proper cooling and air flow in the cavity. To permit adequate ventilation, be sure to install so

as not to block these vents. There should be some space for air circulation.

5) Be sure the exterior of the cooking container and the interior of the oven are dry. Wipe off any moisture with a dry cloth or paper towel.

STEPS OCCURRENCE CAUSE OR CORRECTION

The rated AC voltage is not present between Pin No. 1 of the 3-pin connector (A) and the oven side terminal of the relay RY1

Check supply voltage and oven power cord.

The rated AC voltage is present at primary side of touch control trans-

former.

Touch control transformer or secondary circuit defective. Check and replace the power unit.

Page 22

Page 23

GLBM188HB

6) The Sensor works with food at normal storage temperature. For example, chicken pieces would be at refrigerator temperature and canned soup at room temperature.

7) Avoid using aerosol sprays or cleaning solvents near the oven while using Sensor settings. The sensor will detect the vapor given of by the spray and turn off before food is properly cooked.

8) After the oven is started on sensor cooking condition, if the sensor has not detected the vapor of the food, ERROR will appear and the oven will shut off.

Water load cooking test

WARNING: The oven should be fully assembled before following procedure.

Make sure the oven has been plugged in at least two minutes before checking sensor cook operation. The cabinet should be installed and screws tightened.

1) Fill approximately 200 milliliters of tap water in a 1000 milliliter measuring cup.

2) Place the container on the center of tray in the oven cavity.

3) Close the door.

4) Touch the Timer On-Off pad once, the POWER LEVEL pad twice and the START pad once. And touch the number pads 1 once and the number pad 2 once. Now, the oven is in the sensor cooking condition, and “AH10” and “COOK” will appear in the display.

5) The oven will operate for the first 32 seconds, without generating microwave energy.

NOTE: ERROR will appear if the door is opened or STOP/CLEAR pad is touched during first stage of sensor cooking.

6) After approximately 32 seconds, microwave energy is produced.

If ERROR is displayed or the oven does not turn off, replace the humidity sensor or check the control unit, refer to explanation below.

1. TESTING METHOD FOR HUMIDITY SENSOR AND/OR CONTROL UNIT

To determine if the sensor is defective, the simplest method is to replace it with a new replacement sensor.

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) Remove the humidity sensor.

5) Install the new humidity sensor.

6) Reconnect all leads removed from components during testing.

7) Re-install the outer case (cabinet).

8) Reconnect the power supply cord after the outer case is installed.

9) Reconnect the oven to the power supply and check the sensor cook operation as follows:

a) Fill approximately 200 milliliters of tap water in a 1000 milliliter measuring cup.

b) Place the container on the center of tray in the oven cavity.

c) Close the door.

d) Touch the Timer On-Off pad once, the POWER LEVEL pad twice and the START pad once. And touch the number pads 1 once and the num-

ber pad 2 once.

e) The control panel is in automatic Sensor operation.

f) The oven turns off automatically, and the time for detecting moisture will be displayed.

If new sensor dose not operate properly, the problem is with the control unit, and refer to explanation below.

2. CHECKING CONTROL UNIT

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) Disconnect the sensor connector that is mounted to control panel.

5) Then connect the dummy resistor circuit (see fig.) to the sensor connector of control panel.

6) Disconnect the leads to the primary of the power transformer.

7) Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.

8) After that procedure, re-connect the power supply cord.

9) Check the sensor cook operation proceed as follows:

a) Close the door. Touch the Timer On-Off pad once, the POWER LEVEL pad twice and the START pad once. And touch the number pads 1 once

and the number pad 2 once.

b) The control panel is in the sensor cooking operation.

c) After approximately 41 seconds, push plunger of select switch for more than 3 seconds. This condition is same as judgement by humidity sen-

sor.

Page 23

Page 24

GLBM188HB

d) After approximately 3 seconds, the display shows “X X. X X “ which is the time for detecting moisture.

If the above is not the case, the control unit is probably defective.

If the above is proper, the humidity sensor is probably defective.

10)Disconnect the power supply cord, and then remove outer case.

11)Open the door and block it open.

12)Discharge high voltage capacitor.

13)Disconnect the dummy resistor circuit from the sensor connector of control panel.

14)Carry out necessary repair.

15)Reconnect all leads removed from components during testing and repairing.

16)Re-install the outer case (cabinet).

17)Reconnect the power supply cord after the outer case is installed. Run the oven and check all functions.

18)Carry out “Water load cooking test” again and ensure that the oven works properly.

R1,R2:22Ω±1% 1/2W

R3:4.3kΩ±?5% 1/4W

R4:1MΩ±5% 1/4W

Sensor Dummy Resistor Circuit

[17] Q: NOISE FILTER TEST

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. Disconnect the leads to the primary of the power transformer.

5. Using an ohmmeter, check between the terminals as described in the following table.

If incorrect readings are obtained, replace the noise filter.

6. Reconnect all leads removed from components during testing.

7. Reinstall the outer case (cabinet).

8. Reconnect the power supply cord after the outer case is installed.

9. Run the oven and check all functions.

MEASURING POINT INDICATION OF OHMMETER Between N and H Approx. 470 KΩ Between terminal N and LOAD Short circuit. Between terminal L and LOAD Short circuit.

Plunger

COM

R3 R4

F-1 F-2

F-3

To connector (F) on Control Unit.

CONNECTOR

MONITOR FUSE

NOISE FILTER

NOISE SUPPRESSION COIL

LINE CROSS CAPACITOR

LINE BYPASS

CAPACITOR

0.0033μF / 250V

LINE BYPASS

CAPACITOR

0.0033μF / 250V

LOADLOAD

RESISTOR

470 K

Page 24

Page 25

GLBM188HB

ServiceManual



CHAPTER 9. TOUCH CONTROL PANEL ASSEMBLY

[1] OUTLINE OF TOUCH CONTROL PANEL

The touch control section consists of the following units.

(1) Key unit

(2) Control Unit (Display unit)

(3) Power unit

The principal functions of these units and the signals communicated among them are explained below.

1. Key unit

The key unit is composed of a matrix, signals generated in the LSI are sent to the key unit. When a key pad is touched, a signal is completed through the key unit and passed back to the LSI to perform the function that was requested.

2. Control Unit (Display unit) and Power Unit

Control unit consists of LSI, IC, reset circuit, indicator circuit, power source circuit, relay circuit, buzzer circuit, synchronizing signal circuit, key unit circuit and humidity sensor circuit.

1) IC1 (LSI)

This is a microcomputer, responsible for controlling the entire control unit.

2) IC2

This is the IC to amplify the signal from the humidity sensor.

3) IC3

This is the IC to drive the Fluorescent Display (VFD).

4) Reset Circuit

This circuit generates a signal which resets the LSI (IC1) to the initial state when power is supplied.

5) Indicator Circuit

Indicator element is Fluorescent Display. Basically, a Fluorescent Display is triode having a cathode, a grid and an anode. Usually, the cathode of a Fluorescent Display is directly heated and the filament serves as cathode. The Fluorescent Display has 8-digits, 16segments are used for displaying figures.

6) Power Source Circuit

This circuit generates voltages necessary in the control unit from the AC line voltage. In addition, the synchronizing signal is available in order to compose a basic standard time in the clock circuit.

7) Relay Circuit

A circuit to drive the magnetron, fan motor, antenna motor, hood motor and light the oven lamp and cook top lamp.

8) Buzzer Circuit

The buzzer is responsive to signals from the LSI to emit audible sounds (key touch sound and completion sound).

9) Synchronizing Signal Circuit

The power source synchronizing signal is available in order to compose a basic standard time in the clock circuit. It accompanies a very small error because it works on commercial frequency.

10)Door Sensing Switch

A switch to “tell” the LSI if the door is open or closed.

11)Humidity Sensor Circuit

This circuit detects moisture of the cooking food to allow its automatic cooking.

Symbol Voltage Application

VC -5V LSI(IC1)

Page 25

Page 26

GLBM188HB

[2] HUMIDITY SENSOR CIRCUIT

1. Structure of Humidity Sensor

The humidity sensor includes two thermistors as shown in the illustration. One thermistor is housed in the closed vessel filled with dry air while another in the open vessel. Each sensor is provided with the protective cover made of metal mesh to be protected from the external airflow.

2. Operational Principle of Humidity Sensor

The figure below shows the basic structure of a humidity sensor. A bridge circuit is formed by two thermistors and two resistors (R1 and

R2). The output of the bridge circuit is to be amplified by the opera-

tional amplifier.

Each thermistor is supplied with a current to keep it heated at about 150°C (302°F), the resultant heat is dissipated in the air and if the two thermistors are placed in different humidity conditions they show different degrees of heat conductivity leading to a potential difference between them causing an output voltage from the bridge circuit, the intensity of which is increased as the humidity of the air increases. Since the output is very minute, it is amplified by the operational amplifier.

3. Detector Circuit of Humidity Sensor Circuit

This detector circuit is used to detect the output voltage of the humidity circuit to allow the LSI to control sensor cooking of the unit. When the unit is set in the sensor cooking mode, 32 seconds clearing cycle occurs than the detector circuit starts to function and the LSI observes the initial voltage available at its P65 terminal. With this voltage given, the switches SW1 to SW5 in the LSI are turned on in such a way as to

change the resistance values in parallel with P58 ~ P62 of IC2. Chang-

ing the resistance values results in that there is the same potential at both F-3terminalof the humidity sensor and P66 terminal of the LSI.

The voltage of P65 terminal will indicate about -2.5V. This initial balancing is set up about 32 seconds after the unit is put in the Sensor

Cooking mode. As the sensor cooking proceeds, the food is heated to generate moisture by which the resistance balance the bridge circuit is deviated to increase the voltage available at P65 terminal of the LSI. Then the LSI observes that voltage at P65 terminal and compares it

with its initial value, and when the comparison rate reaches the preset value (fixed for each menu to be cooked), the LSI causes the unit to stop sensor cooking; thereafter, the unit goes in the next operation

automatically. When the LSI starts to detect the initial voltage at P65

terminal 32 seconds after the unit has been put in the Sensor Cooking mode, if it is not possible to balance, of the bridge circuit due to discon- nection of the humidity sensor, ERROR will appear on the display and

the cooking is stopped.

1)Humidity sensor circuit

Ventilation opening for sensing

Sensing part (Open vessel)

Sensing part (Closed vessel)

Thermistors

Operational amplifier

Output voltage

S : Thermistor

open vessel

C : Thermistor

closed vessel

Humidity (g/m )

t volta

humidity vs, output voltage characteristic

SW1

SW2

SW3

SW4

SW5

P70

P71

P72

P73

P74

LSI

(IC1)

P66

P65

620k

300k

150k

75k

37.4k

47k

10k

0.01uF

0.1uF

0.01

VA : -15V

R50

C60

C61

C62

F-2

1.8k

F-1

F-3

3.57k

3.32k

VC : -5V

0.1

C. Thermistor in

closed vessel

S. Thermistor in

open vessel

R58

R59

R50

R51

360k

R53

R52

R54

R55

D61

D60

R60

R61

R62

R57

IC2

Page 26

Page 27

GLBM188HB

[3] SERVICING FOR TOUCH CONTROL PANEL

1. Precautions for Handling Electronic Components

This unit uses CMOS LSI in the integral part of the circuits. When handling these parts, the following precautions should be strictly followed. CMOS LSI have extremely high impedance at its input and output terminals. For this reason, it is easily influenced by the surrounding high voltage power source, static electricity charge in clothes, etc. and sometimes it is not fully protected by the built-in protection circuit.

In order to protect CMOS LSI.

1) When storing and transporting, thoroughly wrap them in aluminium foil. Also wrap all PW boards containing them in aluminium foil.

2) When soldering, ground the technician as shown in the figure and use grounded soldering iron and work table.

2. Servicing of Touch Control Panel

We describe the procedures to permit servicing of the touch control panel of the microwave oven and the precautions you must take when doing so. To perform the servicing, power to the touch control panel is available either from the power line of the oven itself or from an external power source.

1. Servicing the touch control panel with power supply of the oven:

CAUTION: THE HIGH VOLTAGE TRANSFORMER OF THE MICRO-

WAVE OVEN IS STILL LIVE DURING SERVICING AND PRESENTS A HAZARD.

Therefore, before checking the performance of the touch control panel,

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) Disconnect the leads to the primary of the power transformer.

5) Ensure that these leads remain isolated from other components

and oven chassis by using insulation tape.

6) After that procedure, re-connect the power supply cord.

After checking the performance of the touch control panel,

1) Disconnect the power supply cord.

2) Open the door and block it open.

3) Re-connect the leads to the primary of the power transformer.

4) Re-install the outer case (cabinet).

5) Re-connect the power supply cord after the outer case is

installed.

6) Run the oven and check all functions.

a) On some models, the power supply cord between the touch

control panel and the oven itself is so short that the two can't be separated. For those models, check and repair all the controls (sensor-related ones included) of the touch control panel while keeping it connected to the oven.

b) On some models, the power supply cord between the touch

control panel and the oven proper is long enough that they may be separated from each other. For those models, it is possible to check and repair the controls of the touch control panel while keeping it apart from the oven proper; in this case you must short both ends of the door sensing switch (on PWB) of the touch control panel with a jumper, which activates an operational state that is equivalent to the oven door being closed. As for the sensor-related controls of the touch control panel, checking them is possible if dummy resistor(s) with resistance equal to that of the controls are used.

2. Servicing the touch control panel with power supply from an external power source:

Disconnect the touch control panel completely from the oven proper, and short both ends of the door sensing switch (on PWB) of the touch control panel, which brings about an operational state that is equivalent to the oven door being closed. Connect an external power source to the power input terminal of the touch control panel, then it is possible to check and repair the controls of the touch control panel; it is also possible to check the sensor-related controls of the touch control panel by using the dummy resistor(s).

3. Servicing Tools

Tools required to service the touch control panel assembly.

1) Soldering iron: 60W

(It is recommended to use a soldering iron with a grounding terminal.)

2) Oscilloscope: Single beam, frequency range: DC - 10MHz type or more advanced model.

3) Others: Hand tools

4. Other Precautions

1) Before turning on the power source of the control unit, remove the aluminium foil applied for preventing static electricity.

2) Connect the connectors of the key unit to the control unit being sure that the lead wires are not twisted.

3) After aluminium foil is removed, be careful that abnormal voltage

due to static electricity etc. is not applied to the input or output terminals.

4) Attach connectors, electrolytic capacitors, etc. to PWB, making sure that all connections are tight.

5) Be sure to use specified components where high precision is required.

approx. 1M ohm

Page 27

Page 28

GLBM188HB

ServiceManual



CHAPTER 10. PRECAUTIONS FOR USING LEAD-FREE SOLDER

Employing lead-free solder

The “Main PWB” of this model employs lead-free solder. This is indicated by the “LF” symbol printed on the PWB and in the service manual. The suffix letter indicates the alloy type of the solder.

Example:

Using lead-free wire solder

When repairing a PWB with the “LF” symbol, only lead-free solder should be used. (Using normal tin/lead alloy solder may result in cold soldered joints and damage to printed patterns.)

As the melting point of lead-free solder is approximately 40°C higher than tin/lead alloy solder, it is recommend that a dedicated bit is used, and that the iron temperature is adjusted accordingly.

Soldering

As the melting point of lead-free solder (Sn-Ag-Cu) is higher and has poorer wet ability, (flow), to prevent damage to the land of the PWB, extreme care should be taken not to leave the bit in contact with the PWB for an extended period of time. Remove the bit as soon as a good flow is achieved. The high content of tin in lead free solder will cause premature corrosion of the bit. To reduce wear on the bit, reduce the temperature or turn off the iron when it is not required.

Leaving different types of solder on the bit will cause contamination of the different alloys, which will alter their characteristics, making good soldering more difficult. It will be necessary to clean and replace bits more often when using lead-free solder. To reduce bit wear, care should be taken to clean the bit thoroughly after each use.

Indicates lead-free solder of tin, silver and copper

Page 28

Page 29

GLBM188HB

ServiceManual



CHAPTER 11. COMPONENT REPLACEMENT AND ADJUSTMENT PROCE-

DURE

[1] WARNINGS

Please refer to “OVEN PARTS, CABINET PARTS, CONTROL PANEL PARTS, DOOR PARTS”, when carrying out any of the following removal procedures:

[2] THE FOLLOWING ADJUSTMENTS OR COMPONENT REPLACEMENT CAN BE PERFORMED WITHOUT REMOVING THE OVEN FROM THE WALL

1. Cook top lamps, sockets and grease filter.

2. Oven lamp, base cover and lamp glass assembly.

3. Turntable motor.

4. Hood louver.

5. Control panel assembly or components

6. Stirrer cover and stirrer antenna.

[3] REMOVAL OF OVEN FROM WALL (Two persons recommended to remove the oven)

1. Disconnect the power supply cord, and uncoil the power supply cord.

2. Remove the turntable tray and support from the oven cavity.

3. While supporting the front of the oven, unfasten the two (2) screws holding the oven to the unit mounting plate.

4. While supporting the oven, remove the two (2) screws holding the oven (outer case cabinet) to the top cabinet.

5. Remove the oven from the unit mounting plate and pull the power cord out of the wall cabinet.

6. The oven is now free and can be placed on the work surface selected for servicing the oven.

7. Installation is the reverse of this procedure.

Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts may result in severe, possibly fatal, electric shock. (Example) High Voltage Capacitor, Power Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness etc..

WARNING:

Avoid possible exposure to microwave energy. Please follow the instructions below before operating the oven.

WARNING AGAINST HIGH VOLTAGE:

1. Disconnect the power supply cord.

2. Visually check the door and cavity face plate for damage (dents, cracks, signs of arcing etc.).

Carry out any remedial work that is necessary before operat-

ing the oven.

Do not operate the oven if any of the following conditions exist;

1. Door does not close firmly.

2. Door hinge, support or latch hook is damaged.

3. The door gasket or seal is damaged.

4. The door is bent or warped.

5. There are defective parts in the door interlock system.

6. There are defective parts in the microwave generating and transmission assembly.

7. There is visible damage to the oven.

Do not operate the oven:

1. Without the RF gasket (Magnetron).

2. If the wave guide or oven cavity are not intact.

3. If the door is not closed.

4. If the outer case (cabinet) is not fitted.

To prevent an electric shock, take the following precautions.

1. Before wiring,

1) Disconnect the power supply cord.

2) Open the door block it open.

3) Discharge the high voltage capacitor and wait for 60 seconds.

2. Do not let the wire leads touch to the following parts;

1) High voltage parts: Magnetron, High voltage transformer, High voltage capacitor and High voltage rectifier assembly.

2) Hot parts: Oven lamp, Magnetron, Power transformer and Oven cavity.

WARNING FOR WIRING

3) Sharp edge: Bottom plate, Oven cavity, Waveguide flange, Chassis support and other metallic plate.

4) Movable parts (to prevent a fault) Fan blade, Fan motor, Switch, Switch lever, Open button.

3. Do not catch the wire leads in the outer case cabinet.

4. Insert the positive lock connector until its pin is locked and make sure that the wire leads do not come off even if the wire leads are pulled.

5. To prevent an error function, connect the wire leads correctly, referring to the Pictorial Diagram.

Page 29

Page 30

GLBM188HB

[4] HOOD LOUVER REMOVAL

1. Disconnect the power supply cord.

2. Open the oven door and block it open.

3. Remove the one (1) screw holding the outer case cabinet to the oven cavity front face plate (the position is front/ center on the outer case cabinet).

4. Remove the two (2) screws holding the hood louver to the oven cavity.

5. Remove the hood louver from the over by pushing the right and left tabs of the hood louver.

6. Now, the hood louver is free.

[5] OUTER CASE REMOVAL

Remove the oven from the wall and proceed as follows;

1. Disconnect the power supply cord.

2. Open the door and block it open.

3. Remove the one (1) screw holding the outer case cabinet to the oven cavity front face plate (the position is front/ center on the outer case cabinet).

4. Remove six (6) screws holding the rear stay to the hood fan motor or the oven, and remove it.

5. Remove the six (6) screws from the rear of the outer case cabinet.

6. Slide the outer case cabinet back about 1 inch (3 cm) to free it from retaining clips on the cavity face plate.

7. Disconnect the three (3) pin connector of the power supply cord from the wiring harness and remove the power supply cord together with the outer case.

8. Discharge high voltage capacitor.

CAUTION: 1) DISCONNECT OVEN FROM POWER SUPPLY

BEFORE REMOVING OUTER CASE.

2) DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING.

[6] POWER TRANSFORMER REMOVAL

1. Removal

1. Disconnect the power supply cord, remove the oven from wall, and remove outer case. (Refer to procedure of “REMOVAL of OVEN FROM WALL” and “OUTER CASE REMOVAL”.) And proceed as follows.

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Disconnect filament leads of transformer from the magnetron and capacitor.

5. Disconnect high voltage leads of capacitor from the transformer.

6. Remove one (1) screw holding the capacitor holder to fan duct and remove the capacitor.

7. Disconnect wire leads from transformer.

8. Remove three (3) screws holding the deflector to the cavity face plate and remove the deflector.

9. Remove three (3) screws holding the base cover to the cavity face plate and one (1) screw holding the base cover to the cavity back plate, and remove the base cover.

10.Remove two (2) screws holding the transformer to right base plate.

2. Re-install

1. Install by sliding the transformer on the right base plate with its primary terminals toward the fan duct.

2. Secure the transformer with two (2) screws to right base plate.

3. Re-connect wire leads (primary and high voltage) to the transformer and filament leads of transformer to magnetron and high voltage capacitor. Refer to “PICTORIAL DIAGRAM”.

4. Re-install the capacitor.

5. Re-install the base cover and the deflector.

6. Re-install the outer case and check that oven is operating properly.

CAUTION: MAKE SURE THE WIRE LEADS NEVER TOUCH THE

FAN BLADE.

[7] HOOD FAN MOTOR, HOOD DUCT, OVEN LAMP SOCKET AND HUMIDITY SENSOR REMOVAL

1. Disconnect the power supply cord and remove the oven from wall and remove outer case. (Refer to procedure of “Removal of Oven from Wall” and “Outer Case Removal”.)

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Remove the hood louver refer to procedure of HOOD LOUVER REMOVAL.

5. Remove two (2) screws holding the chassis support right to the rear and face of the oven cavity flanges.

6. Remove two (2) screw holding the chassis support left to the rear flange and face of the oven cavity flanges.

7. Remove the both chassis support.

8. Remove the wire tie holding the hood fan harness to the hood duct by cutting it.

9. Disconnect the 6-pin connector of the hood fan motor from the main wire harness located at the right edge of the hood duct. Remove one (1) screw holding the hood intake duct to right base plate. Remove one (1) screw holding the hood duct to the hood intake duct right. And remove the hood intake duct right.

Release the snap band from the cavity top plate.

10.Disconnect the two (2) grounding wire from the chassis support left.

11.Now, the hood fan motor is free.

Hood louver

Screw

Outer case cabinet

Screw

Page 30

Page 31

GLBM188HB

12.Remove the one (1) screw holding the noise filter assembly to the fan duct.

13.Disconnect the connector CN-F and CN-D from the control unit.

14.Remove one (1) screw holding the hood duct to the oven cavity top plate.

15.Remove the one (1) screw holding the hood duct to the fan duct.

16.Release the 6-pin connector and the 3-pin connector of the main

harness A from the hood duct.

17.Disconnect the control harness A from the control harness B.

18.Disconnect the connector of control harness A from the cavity face

plate.

19.Remove the hood duct from the oven cavity by lifting it up.

20. Release the snap band of control harness A from the hood duct.

21.Release the harness of the sensor assembly and the control har- ness A from four(4) wire holders of the hood duct.

22.Remove two (2) screws holding the sensor assembly to the hood duct.

23.Now, the sensor assembly is free.

24.Lift the oven lamp cover up and remove the oven lamp cover from hood duct.

25.Remove the oven lamp (Refer to the procedure of “Oven lamp removal”).

26.Disconnect the wire leads from the oven lamp socket.

27.Rotate the oven lamp socket to remove from hood duct.

28.Now, the oven lamp socket is free.

NOTE: When the hood fan motor is reinstalled, hold the hood

fan motor harness at the right edge of the hood duct with one wire tie.

Top view of the microwave oven

[8] MAGNETRON REMOVAL

1. Disconnect the power supply cord, remove the oven from wall and remove outer case (Refer to procedure of “Removal of Oven from Wall” and “Outer Case Removal”.)

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Remove two (2) screws holding the chassis support right to the rear and face of the oven cavity flanges.

5. Remove the one (1) screw holding the noise filter assembly to the fan duct.

6. Disconnect the wire leads from the fan motor.

7. Disconnect the high voltage wire leads of the high voltage rectifier

assembly from the magnetron.

8. Disconnect the filament lead of the transformer from the magne-

tron.

9. Remove the one(1) screw holding the hood duct to the fan duct and remove the one (1) screw holding the oven cavity top plate to the fan duct.

10.Remove the one(1) screw holding the right base plate to the fan duct and remove the fan duct assembly

11.Remove the power transformer from the right base plate, referring to “POWER TRANSFORMER REMOVAL“.

12.Carefully remove four (4) mounting screws holding the magnetron to waveguide. When removing the screws hold the magnetron to

prevent it from falling.

13.Remove the magnetron from the unit with care so the magnetron

tube should not be hit by any metal object around the tube.

CAUTION: CAUTION: WHEN REPLACING THE MAGNETRON, BE

SURE THE R.F. GASKET IS IN PLACE AND MOUNTING SCREWS ARE TIGHTENED SECURELY.

[9] HIGH VOLTAGE RECTIFIER AND HIGH VOLTAGE CAPACITOR REMOVAL

1. Disconnect the power supply cord, remove the oven from wall and remove outer case (Refer to procedure of “Removal of Oven from Wall” and “Outer Case Removal”.)

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Disconnect the high voltage wire leads with high voltage rectifier

from the magnetron.

5. Disconnect filament lead of the transformer from high voltage

capacitor.

6. Disconnect high voltage wire from capacitor.

7. Remove one (1) screw holding capacitor holder and high voltage rectifier to the fan duct.

8. Disconnect the high voltage rectifier assembly from the high voltage capacitor and remove one (1) screw holding the voltage recti-

fier assembly to the capacitor holder.

9. Now, the high voltage rectifier assembly is free.

10.Remove capacitor from the holder.

11.Now, the high voltage capacitor is free.

CAUTION: WHEN REPLACING THE HIGH VOLTAGE RECTIFIER

ASSEMBLY, THE GROUND SIDE TERMINAL MUST BE SECURED FIRMLY WITH A GROUNDING SCREW.

Hood fan duct

Wire tie

Hood fan motor

Hood fan motor harness

Wire tie

Page 31

Page 32

GLBM188HB

[10] HOOD FAN THERMOSTAT (60ºC ON) REMOVAL

1. Disconnect the power supply cord, remove the oven from wall and

remove outer case (Refer to procedure of “Removal of Oven from Wall” and “Outer Case Removal”.

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Disconnect the wire leads from the hood fan thermostat (60°C ON).

5. Remove one (1) screw holding the thermostat (60°C ON) to the right base plate.

6. Remove the hood fan thermostat (60°C ON) from the right base

plate.

7. Now, the hood fan thermostat (60°C ON) is free.

[11] COOLING FAN MOTOR REMOVAL

1. REMOVAL

1. Disconnect the power supply cord, remove the oven from wall and

remove outer case (Refer to procedure of “Removal of Oven from Wall” and “Outer case Removal”.)

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Remove two (2) screws holding the chassis support right to the rear and face of the oven cavity flange.

5. Remove the one(1) screw holding the noise filter assembly to the fan duct.

6. Disconnect the wire leads from the fan motor.

7. Disconnect the high voltage wire leads of the high voltage rectifier

assembly from the magnetron.

8. Disconnect the filament lead of the transformer from the magnetron.

9. Remove the one(1) screw holding the hood duct to the fan duct and remove the one (1) screw holding the oven cavity top plate to

the fan duct.

10.Remove the one (1) screw holding the right base plate to the fan duct and remove the fan duct assembly

11.Remove the fan blade from the fan motor shaft according the fol-

lowing procedure.

12.Hold the edge of the rotor of the fan motor by using a pair of groove

joint pliers.

CAUTION: * Make sure that any pieces do not enter the gap

between the rotor and the stator of the fan motor. Because the rotor is easy to be shaven by pliers and metal pieces may be produced.

* Do not touch the pliers to the coil of the fan motor

because the coil may be cut or damaged.

* Do not disfigure the bracket by touching with the

pliers.

13.Remove the fan blade from the shaft of the fan motor by pulling and rotating the fan blade with your hand.

14.Now, the fan blade will be free.

CAUTION: Do not re-use the removed fan blade because the hole

(for shaft) may be larger than normal.

15.Remove the two (2) screws holding the fan motor to the fan duct.

16.Now, the fan motor is free.

2. INSTALLATION

1. Install the fan motor to the fan duct with the two (2) screws.

2. Install the fan blade to the fan motor shaft according to the following

procedure.

3. Hold the center of the bracket which supports the shaft of the fan motor on the flat table.

4. Apply the screw lock tight into the hole (for shaft) of the fan blade.

5. Install the fan blade to the shaft of fan motor by pushing the fan blade with a small, light weight, ball peen hammer or rubber mallet.

CAUTION: * Do not hit the fan blade strongly when installed

because the bracket may be transformed.

* Make sure that the fan blade rotates smoothly after

installed.

* Make sure that the axis of the shaft is not slanted.

6. Install the fan duct to the oven cavity, base plate right and hood duct with the three (3) screws.

7. Connect the high voltage wire leads with high voltage rectifier from

the magnetron, referring to the pictorial diagram.

8. Connect filament lead of the transformer from high voltage capaci-

tor, referring to the pictorial diagram.

9. Connect high voltage wire from capacitor, referring to the pictorial

diagram.

10.Connect the wire leads to the fan motor, referring to the pictorial

diagram.

11.Refer to procedure of “Outer case Removal“. And reverse their procedure. And re-install the outer case.

Thermostat (60ºC ON)

Right Base plate

Gap

Bracket

Stator

Coil

Shaft

Axis

Stator

Rotor

These are the positions that should be pinched with pliers.

Shaft

Table

Center of bracket

Rear View

Side View

Rotor

Groove joint pliers

Page 32

Page 33

GLBM188HB

[12] TURNTABLE MOTOR REMOVAL

1. Disconnect the power supply cord.

2. Open the door and block it open.

3. Remove the three(3) screws holding the deflector to the cavity face plate.

4. Remove the four (4) screws holding the base cover to the oven cavity.

5. Remove the base cover from the oven cavity by pulling down and

moving to the left slightly.

6. Disconnect the wire leads from the turntable motor.

7. Remove one (1) screw holding turntable motor to the oven cavity.

8. Now the turntable motor is free.

[13] ANTENNA MOTOR REMOVAL

1. Disconnect the power supply cord and remove the oven from wall

and outer case. (Refer to procedure of “Removal of Oven from Wall” and Outer case Removal”)

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Remove the hood duct from the oven cavity, referring to the proce-

dure of “HOOD FAN MOTOR, HOOD DUCT AND OVEN LAMP SOCKET REMOVAL”.

5. Disconnect the wire leads from the antenna motor.

6. Remove the one (1) screw holding the antenna motor to the waveguide of the oven cavity.

7. Remove the antenna motor from the waveguide.

8. Now, the antenna motor is free.

9. When installing the antenna motor, the shaft of antenna motor must

be inserted to the antenna shaft. Refer to the procedure of “STIRRER COVER AND STIRRER FAN INSTALLATION”.

[14] STIRRER COVER AND STIRRER ANTENNA INSTALLATION

1. Put the stirrer antenna fan on the wave guide to match the stirrer

antenna shaft to the center of the stirrer hole.

2. Insert the shaft of stirrer antenna to the shaft of stirrer antenna

motor.

3. Rotate the antenna holder to lock at the cavity top plate.

4. Insert the cutout of stirrer cover to the tabs on the ceiling.

5. Install the stirrer cover to the oven cavity, and secure it by one

canoe clip

[15] OVEN LAMP REMOVAL

1. Disconnect the power supply cord.

2. Remove the hood louver from the oven. (Refer to procedure of

“HOOD LOUVER REMOVAL”)

3. Lift the oven lamp cover up.

4. Now, the oven lamp and the socket are found.

5. Screw the oven lamp off from the lamp socket.

6. Now, the oven lamp is free.

[16] POSITIVE LOCK CONNECTOR (NO-CASE TYPE) REMOVAL

1. Disconnect the power supply cord and remove the oven from wall

and outer case. (Refer to procedure of “Removal of Oven from Wall” and Outer case Removal”)

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Push the lever of positive lock£ connector.

5. Pull down on the positive lock£ connector.

CAUTION: WHEN CONNECTING THE POSITIVE LOCK£ CONNEC-

TORS TO THE TERMINALS, INSTALL THE POSITIVE LOCK£ SO THAT THE LEVER FACES YOU.

Positive lock£, connector

[17] RIGHT PANEL ASSEMBLY AND POWER UNIT REMOVAL

1. Disconnect the power supply cord.

2. Open the door and block it open.

3. Remove the hood louver from the oven. (Refer to procedure of

“HOOD LOUVER REMOVAL”)

4. Remove one (1) screw holding the right panel to the oven cavity front face plate.

5. Release the right panel from the oven cavity front face plate by lifting it up.

6. Disconnect the wire leads from the relays RY1 and RY2.

7. Disconnect the connectors CN-A, CN-B, CN-C, CN-D, CN-E and CN-F from the control unit.

8. Remove the right panel assembly from the oven.

9. Now, the right panel assembly is free.

10.Remove four (4) screws holding the power unit to the key fixing plate and right panel.

11.Now, the power unit is free.

Shaft

Stirrer Antenna

Stirrer Cover

Canoe Clip

Terminal

Push

Pull down

Lever

Positive lock¨ connector

Page 33

Page 34

GLBM188HB

[18] DOOR SENSING SWITCH, SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH REMOVAL

1. REMOVAL

1. Disconnect the power supply cord and remove the oven from wall

and remove outer case. (Refer to procedure of “Removal of Oven from Wall” and “Outer case Removal”)

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Remove the control panel assembly, referring to the procedure of “CONTROL PANEL ASSEMBLY, CONTROL UNIT AND KEY UNIT REMOVAL”.

5. Remove the two (2) screws holding the latch hook to the oven cav-

ity front flange.

6. Remove the latch hook from the oven cavity front flange.

7. Disconnect the wire leads of each switch.

8. Remove each switch from the latch hook by pushing the one (1) stopper tub holding each switch.

9. Now, each switch is free.

2. REINSTALL

1. Re-install each switch in its place. The secondary interlock switch is in the lower position, door sensing switch is in the upper position

and the monitor switch is in the middle position.

2. Re-connect wire leads to each switch. Refer to pictorial diagram.

3. Secure the latch hook (with two (2) mounting screws) to oven cavity

front flange.

4. Make sure that the monitor switch is operating properly and check continuity of the monitor circuit. Refer to chapter “Test Procedure” and “Adjustment procedure”.

[19] DOOR SENSING SWITCH, SECONDARY INTERLOCK SWITCH, AND MONITOR SWITCH ADJUSTMENT

1. Adjustment

1. Disconnect the power supply cord and remove the oven from wall

and remove outer case. (Refer to procedure of “Removal of Oven from Wall” and “Outer case Removal”)

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Remove the right panel assembly, referring to the procedure of “RIFGT PANEL ASSEMBLY AND POWER UNIT REMOVAL”.

If the door sensing switch, secondary interlock switch and monitor switch do not operate properly due to a misadjustment, the following adjustment should be made.

5. Loosen the two (2) screws holding latch hook to the oven cavity

front flange.

6. With door closed, adjust latch hook by moving it back and forth, and up and down. In and out play of the door allowed by the upper and lower position of the latch hook should be less than 0.5mm. The vertical position of the latch hook should be adjusted so that the door sensing switch, secondary interlock switch are activated with the door closed. The horizontal position of the latch hook should be adjusted so that the monitor switch is activated with the

door closed.

7. Secure the screws with washers firmly.

8. Check all of the switches operation. If any switch has not activated with the door closed, loosen screw and adjust the latch hook posi-

tion.

2. After adjustment, check the following.

1. In and out play of door remains less than 0.5mm when in the latched position. First check upper position of latch hook, pushing

and pulling upper portion of door toward the oven face.

Then check lower portion of the latch hook, pushing and pulling

lower portion of the door toward the oven face. Both results (play in

the door) should be less than 0.5mm.

2. The door sensing switch, and secondary interlock switch interrupt the circuit before the door can be opened.

3. Monitor switch contacts close when door is opened.

4. The contact of door sensing switch and secondary interlock switch open within 1.2mm gap between right side of cavity face plate and

door when door is open.

5. Re-install outer case and check for microwave leakage around door with an approved microwave survey meter. (Refer to Microwave Measurement Procedure.)

Figure C-1. Latch Switch Adjustments

[20] DOOR REPLACEMENT

1. REMOVAL

1. Disconnect the power supply cord and remove the oven from wall

and remove outer case. (Refer to procedure of “Removal of Oven from Wall” and “Outer case Removal”)

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Remove the hood louver from the oven. (Refer to the procedure of

“HOOD LOUVER REMOVAL”.)

5. Insert a putty knife (thickness of about 0.5mm) into the gap A between the door stopper and the choke cover as shown in Figure C-3 to free engaging parts.

6. Lift up the door stopper.

7. Now, the door stopper is free from the door assembly.

Secondary Interlock Switch

Monitor Switch

Latch Hook

Door

Latch Heads

Door Sensing Switch

Page 34

Page 35

GLBM188HB

8. Lift up the door assembly to release the upper and lower door hinge pins from the upper and lower oven hinges.

9. Now, the door assembly is free.

NOTE: When the individual parts are replaced, refer to “Door Disas-

sembly”.

2. REINSTALL

1. On re-installing door, insert the lower oven hinge to lower door

hinge pin.

2. Insert the upper oven hinge to the upper door hinge pin.

3. Shut the door (close the contacts of interlock switches).

4. Make sure upper and lower oven hinges are inserted into the upper an lower door hinge pins.

5. Make sure the door is parallel with oven face lines (left and upper side lines) and door latch heads pass through latch holes correctly.

6. Re-install the door stopper to the door assembly.

7. Re-install the hood louver to the oven cavity front face plate.

NOTE: After any service to the door;

1) Make sure that door sensing switch and secondary

interlock switch are operating properly. (Refer to chap-

ter “Test Procedures”.).

2) An approved microwave survey meter should be used

to assure compliance with proper microwave radiation emission limitation standards.

3. After any servicing, make sure of the following:

1. Door latch heads smoothly catch latch hook through latch holes

and that latch head goes through center of latch hole.

2. Deviation of door alignment from horizontal line of cavity face plate is to be less than 1.0mm.

3. Door is positioned with its face pressed toward cavity face plate.

4. Re-install outer case and check for microwave leakage around

door with an approved microwave survey meter. (Refer to Micro- wave Measurement Procedure.)

NOTE: The door on a microwave oven is designed to act as an

electronic seal preventing the leakage of microwave energy from oven cavity during cook cycle. This function does not require that door be air-tight, moisture (conden-

sation)-tight or light-tight. Therefore, occasional appear-

ance of moisture, light or sensing of gentle warm air movement around oven door is not abnormal and do not of themselves indicate a leakage of microwave energy from oven cavity.

Figure C-2. Door Replacement and adjustment

[21] DOOR DISASSEMBLY

1. Disconnect the power supply cord and remove the oven from wall and remove outer case. (Refer to procedure of “Removal of Oven from Wall” and “Outer case Removal”)

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Remove the hood louver from the oven cavity. (Refer to the procedure of “HOOD LOUVER REMOVAL”.)

5. Remove door assembly, refer to “Door Replacement”. Replace-

ment of door components are as follows:

6. Place door assembly on a soft cloth with latches facing up.

NOTE: Note: As the engaging part of choke cover and door frame are

provided at 16 places, do not force any particular part.

CHOKE COVER

7. Insert a putty knife (thickness of about 0.5mm) into the gap A

between the choke cover and door stopper and between the choke

cover and the door frame as shown Figure C-3 to free engaging

parts.

8. Pry the choke cover by inserting a putty knife in order shown in Figure C-3.

9. Now choke cover is free from door panel and door frame.

LATCH SPRING, LATCH HEAD AND DOOR PANEL

10.Release the latch spring from the tab of the latch head and tab of the door panel.

11.Release the latch head from the door panel.

12.Now, the latch spring, latch head and door panel are free.

DOOR FRAME

13.Remove eight (8) screws holding the door panel to the door frame assembly.

14.Release the door frame assembly from the door panel.

NOTE: NOTE: It is easier to release the engaging parts of the upper

or lower door hinge pin side at first.

15.Now, door frame assembly is free.

Figure C-3. Door Disassembly

DISPLAY UNIT

16.Remove two (2) screws holding the control unit cover to the door flame assembly.

17.Release the control unit cover from the door flame assembly.

18.Disconnect the connect CN-J from the display unit.

Upper Oven Hinge

Lower Oven Hinge

Upper Door Hinge Pin

Door assembly

RE-INSTALL

Hood Louver

Latch Heads

Lower Door Hinge Pin

Choke Cover

Door Frame

Door Stopper

Putty Knife

Page 35

Page 36

GLBM188HB

19.Disconnect the connector CN-G from the switch unit.

20.Remove the six (6) screws holding the display unit to the key fixing frame.

21.Now the display unit is free.

[22] COOK TOP LAMP SOCKET REMOVAL

1. Disconnect the power supply cord.

2. Remove the three (3) screws holding the deflector to the base cover.

3. Remove the four (4) screws holding the base cover to the oven cavity.

4. Pull down and slide to left the base cover. And remove the base cover from the cavity back plate.

5. Disconnect the wire leads from the lamp socket.

6. Screw the oven lamp off the lamp socket.

7. Screws the lamp socket off the lamp mounting angle.

8. Now, the lamp socket is free.

Page 36

Page 37

GLBM188HB

ServiceManual



CHAPTER 12. CIRCUIT DIAGRAMS

[1] Pictorial Diagram

Figure S-1. Pictorial Diagram

DOOR SENSING SWITCH

MONITOR SWITCH

SECONDARY INTERLOCK SWITCH

POWER TRANSFORMER

CN-C

RY1

CN-B

CN-A

BRN

PPL

BLK

2 3 4 5 6 7 8 7

BLK RED

RED

GRN

RED

GRN

YLW WHT

WHT/WHT

RED

GRY/GRY

5 4 3 2 1

GRY ORG BRN

Control harness B

CN-D

BLK/BLK

BLK

WHT

GRY/WHT

GRY

RY2

MAGNETRON

H.V. CAPACITOR

BLK

WHT/GRY

CN-F

HUMIDITY SENSOR

BLK

RED

BLK

BRN

MAGNETRON TEMP.FUSE

WHT

1 3

6 3 2 4 5 1

RY5

HOOD FAN MOTOR

WHT

RY6

RY7

BLK

WHT

BRN

WHT

N. O.

OVEN LAMP RELAY

COM.

GRY

CONTROL UNIT

DOOR UNIT

WHT

ANTENNA

MOTOR

YLW

WHT

YLW

RED

WHT

D40

20W

RED

GRN

DOOR SENSING

SWITCH

WHT

RY1

BRN

RED

VRS1

RY8

HUMIDITY SENSOR

BLK

PRIMARY INTERLOCK RELAY

LOW VOLTAGE TRANSFORMER

RY2

COM.

N.O.

RED

BLK

BLK BRN

RY3

TURNTABLE MOTOR RELAY

CN-L

CN-J

CN-G

FAN

MOTOR

WHT

YLW

GRY

WHT

MONITOR

SWITCH

WHT

GRY

SECONDARY INTERLOCK SWITCH

OVEN LAMP

20W

TURNTABLE

MOTOR

TTM

ATM

COM.

HIGH VOLTAGE RECTIFIER

HIGH VOLTAGE CAPACITOR

0.94uF 2300VAC

POWER TRANSFORMER

NOTES:

1. Circuits subject to change without notice

2. The neutral wire(White or Gray wire) must be connected to the prescribed tab terminal of the lamp socket.

3. Only certain models use the humidity sensor.

4. The neutral wire(White/Gray wire) must be connected to the winding end tab terminal of the power transformer primary winding.

5. Only PLBMZ189HC has the earth wire.

MAGNETRON

POWER UNIT

145ºC

60ºC

120ºC

150ºC

OVEN THERMAL CUT OUT

HOOD FAN THERMOSTAT

High

Low

COOK TOP LAMP

N.O.

*NOTE 2

*NOTE 3

*NOTE 2

*NOTE 5

*NOTE 4

GRN

CN-M

CN-N

CN-D

GND

120V AC 60Hz

COM

N.O.

RED

YLW

BLK BLK

PPL

BLK

WHT WHT

NOISE SUPRESSION COIL 1.0mH

LINE BYPASS CAPACITOR

3300pF 250V

FUSE

20A

LINE BYPASS CAPACITOR

3300pF 250V

NOISE FILTER UNIT

RED

BLK

GRY

ORG

SWITCH UNIT

ORG : ORANGE

BLK : BLACK BRN : BROWN

PNK : PINK

RED : RED YLW : YELLOW

PPL : PURPLE

BLU : BLUE

GRY : GRAY WHT : WHITE

LEAD WIRE COLOR CODE

GRN : GREEN

Page 37

Page 38

GLBM188HB

[2] Power Unit Circuit

Figure S-2. Power Unit Circuit

<NOTE> IF NOT SPECIFIED

: 1SS355 or HSU119 or KDS160

: DTA143EKA or KRA101S

: 0.01uF / 50V

: 1/10W, ±5%

CN-E

B2P-VH-B

DOOR SW

CN-T

B6B-XH-A

CN-D

B11B-PASK-1

IC-1

SUB RST

SUB INT

SCK

D41

C100

RY2

DU24D1-1P(M)-R-CF

RY7

G5NB-1A DC24V

RY6

G5NB-1A DC24V

RY3

G5NB-1A DC24V

RY5

G5SB-14 DC24V

RY8

G5NB-1A DC24V

COM

MOTOR

RUN

CAPACITOR

MICRO

HL Low

HL High

HM Low

HM High

OL/FM/AM

SENSOR

AC120V

60Hz

CN-A

CN-B

CN-C

FUSE

2.5A

VRS1

S10K300

CN-F

B3B-EH

TTM

6.8u/230V

C40

R20

R10

R11

R12

R13

R14

CF1

C11

P15

P16

P27

P50

P51

P52

P53

P54

P30

P31

P32

P33

P34

P35

P36

P37

P75 P76 P77 P40 P41 P42 P43 P44 P45 P46 P47 P10 P11 P12 P13 P14

SCK1

SO1

SI1

P03 TXD1 RXD1

INT0

P20

RESET

P22

P21

VDD TEST XOUT

XIN

VSS

P74

P73

P72

P71

P70

P67

P66

P65

P64

P63

P62

P61

P60

AVDD

VAREF

P07

C62

C63

0.1u/50V

4MHz

10K

4.7K x5

Q29

Q27

Q26

Q25

Q24

Q22

Q20

C20

Q21

R51

KTA1046Y

Q31

IC-2

R54

Q10

OUT

8.2

47u/ 16V

D1 - 4: 1N4002 x4

COM

680 1/2W

KIA79L05BP

D11

D10

GND

(0V)

GND

(0V)

VSS

(-5V)

Q11

DTA143ES

KRA117S

10K

3.32KD

DTD143ES

B5P9-VH-B

B2P3-VH-B

B3P5-VH-B

C21

R62

R50

R32

(J1)

R56

HZU16B1

ZD1

1/4W

2.4K

(ZD2)

C10

ZD3

HZU3.6B2

47u/16V

15K

D60

D61

3.57KD

C60

C61

0.1u/50V

0.1u/50V 10u/35V

1000u/35V

0.1u/50V

330 1W

R61

R60

R59

R58

R57

R55

R52

R53

75KF

300K

360KF

620K

47K

150KF

1.8KF

37.4KD

R37

R36

3.3K

1.2K

0.1U/50V

10U/35V

D40

D21

D27 D26 D25

D24

D22 D20

R100

30K 1/2W

R40

R41

15K

12345

TEST

TXD

RXD

RST

4.7K

RY1

DU24D1-1P(M)-R-CF

1 3 4

8 7 6 5

Page 38

Page 39

GLBM188HB

[3] Key Unit and Display Unit Circuit

Figure S-3. Key Unit and Display Unit Circuit

<NOTE> IF NOT SPECIFIED

: 1/10W ±5%

: 0.1u/50V

: NOT INSERT PARTS( )

R93

R92

R91

R90

R89

R88

R87

R86

R85

R84

R83

R82

R81

R80

R79

R78

R77

R76

R75

R74

R73

R72

R71

R70

100K x24

KRA101S x24

C15

P15

P16

P17

SCL

SDA

P52

P53

P54

P30

P31

P32

P33

P34

P35

P36

P37

P14

P13

P12

P11

P10

P47

P46

P45

P44

P43

P42

P41

P40

P77

P76

P75

VSS

XIN

XOUT

TEST

VDD

P21

P22

RESET

P20

INT0

RXD1

TXD1

P03

SI1

SO1

SCK1

P74

P73

P72

P71

P70

P67

P66

P65

P64

P63

P62

P61

P60

AVDD

VAREF

P07

IC-3

0.1u/50V

C17

330p/50V

C16

0.1u/50V

4.7K

270K

4.7K

R222

R67

R66

R65

R64

R63

G6G7

P30

P10

P11

P12

P13

G10

P14

G11

P15

G12

P16

G13

P17

P31

P32

P33

P34

R42

C42

C42 - C46: 330pF x 5

C43

C44

C45

C46

P30

P31

P32

P33

P34

R42 - R46: 15K x 5

R43

R44

R45

R46

J11

J10

2,3

P10

P11

P12

P13

P14

P15

P16

33,34

CN-J

CN-G

(CN-K)

S11B-PASK-2

13FEL2-SRTN

VFD

(B6B-XH-A)

TEST

TXD

RXD

RST

12345

(0V) GND

(-5V) VSS

SCK

R17

R16

R15

P17

P16

P15

P14

P13

P12

P11

P10

R22

R23

R21

15K

R24

15K

R25

R26

R27

R28

15K

10K

CF2

4MHz

R18

R19

4.7K x3

4.7K x2

SUB INT

SUB RST

Q70

Q71

Q72

Q73

Q74

Q75

Q76

Q77

Q78

Q79

Q80

Q81

Q82

Q83

Q84

Q85

Q86

Q87

Q88

Q89

Q90

Q91

Q92

Q93

P47

P46

P45

P44

P43

P42

P41

P40

P77

P76

P75

P74

P73

P72

P71

P70

P67

P66

P65

P64

P63

P62

P61

P60

KEY UNIT

Power

Level

User

Pref

Baked

Potato

Timer

On-Off

Vent

Hi/Lo/Off

Sensor

Reheat

Auto

Defrost

Keep

Warm

Melt

Soften

Light

Hi/Lo/Off

Veggies

Popcorn

Snacks

Auto

Cook

Sensor

Cook

START

ENTER

Turn

Table

On/Off

STOP

CLEAR

Add

30 Sec.

Page 39

Page 40

GLBM188HB

[4] Printed Wiring Board

Figure S-4. Printed Wiring Board

CN-T

JP4

JP3

C30

JP5

JP7

JP8

JP9

R50

JP10

JP11

JP12

JP13

Q10

9865

RY5

1 7

CN-B

JP15

JP16

CN-D

JP23

JP30

JP29

JP31

JP26

CN-E

RY2

C21

Q21

C100

JP22

JP21

DIP

JP32

C10

JP2

CN-F

JP1

JP6

JP18

JP19

JP17

JP20 JP24

JP25 JP27

JP28

C B

1 2

I O

CF1

RY4

RY1

RY3RY9

RY8RY7RY6

R100

CN-C

D29

CN-A

VRS1

FUSE 2.5A

Page 40

Page 41

GLBM188HB

MEMO

Page 41

Page 42

GLBM188HB

[1] OVEN PARTS

107

110

108

107

108

109

113

108

107

113

117

107

111

107

108

105

23-1

23-2

116

105

76-4

105 76-4

107

130

107

106

108

114

107

76-1

76-2

76-3

76-4

76-5

76-6

Page 42

Page 43

[1] OVE N PARTS

ELECTRIC PARTS

2 3 3 4 4 5

9 10 11 12 13 14 14 15 15 15 15 16 17 17 17 17 17 19 19

CABINET PARTS

22 23

23-1 23-2

24 25 26 27 28 29

OVEN PARTS

34 36 37 37 38 39 40 41 42 43

* 44

45 46 47 48 48 48 49 50 51 52 53 53 54 55 57 58 59 60 61 62 76

76-1 76-2 76-3 76-4 76-5 76-6

H.V rectier HV capacitor HV capacitor (Interchangeable) Turntable motor Turntable motor (Interchangeable) Antenna motor Antenna motor (Interchangeable) Thermal cut out 60C (Hood fan) Power transformer

Magnetron

Magnetron(Interchangeable)

Pri. Interlock and door sensing switches Monitor switch (D3V-1G-2C25)and fuse assembly (20A 250V) Power supply cord Lamp socket Hood motor assembly Fan motor Noise lter Noise lter (Interchangeable) Thermal cut out (Oven) Thermal cut out (Oven) (Interchangeable) Thermal cut out (Oven) (Interchangeable) Thermal cut out (Oven) (Interchangeable) Humidity sensor assembly DM 150V fuse (Magnetron) Thermal cut out (Magnetron) (Interchangeable) Thermal cut out (Magnetron) (Interchangeable) Thermal cut out (Magnetron) (Interchangeable) Thermal cut out (Magnetron) (Interchangeable) Oven light (cook top lamp, oven lamp) Oven light (cook top lamp, oven lamp) (Interchangeable)

Schematic diagram Lamp glass assembly Hood lamp glass ag black Lamp glass Lamp mounting angle Rear stay Base cover Lamp cover Fan duct Unit mounting plate

Screw; 3mm x 8mm Damper assembly Outer case cabinet [PLBMV188HC] [GLBM188HB] Outer case cabinet [GLBM188HS] Turntable HV. capacitor band Stirrer cover Stirrer antenna assembly Roller assembly TTM packing Latch hook Harness cover Fan blade Cord bushing Hood louver assembly [PLBMV188HC] Hood louver [GLBM188HS] Hood louver [GLBM188HB] Hood intake duct R Cushion Lamp lter Chassis support Deector [GLBM188HB] [PLBMV188HC] Deector [GLBM188HS] Hood duct Rack holder Barrier HVT cushion Cushion Base plate right Rack holder L Rack holder R Accessory assembly Grommet Special screw Machine screw Tap tight screw Tapping screw Washer

DESCRIPTION

NOITPIRCSED.ON

77 Hood lamp reector 78 Menu label 80 Cushion 81 Cushion 90 DHHS ground caution 91 Monitor caution 92 Filter 93 Mesh lter 94 Canoe clip 95 Rack 96 Filter 98 Control harness B [PLBMV188HC] 98 Control harness B [GLBM188HS] [GLBM188HB] 99 Cushion

130 DHHS caution

105 Screw; 4mm x 8mm [PLBMV188HC] [GLBM188HB] 105 Screw; 4mm x 8mm [GLBM188HS] 106 Screw; 3mm x 8mm 107 Screw; 4mm x 8mm 108 Screw; 4mm x 8mm 109 Screw; 4mm x 8mm 110 Screw : 4mm x 8mm 111 Screw; 4mm x 8mm 113 Screw; 3mm x 6mm 114 Special screw 116 Screw; 4mm x 8mm 117 Wire holder

[1] OVEN PARTS

SCREWS, WIRE HOLDER

Page 43

Page 44

[2] DOOR AND CONTROL P ANEL PARTS FOR PLBMV188HC

207

101

118

208

100

206

205

202

209

200

100

203

101

204

210

NOITPIRCSED.ON

[2] DOOR AND CONTROL PANEL PARTS FOR PLBMV188HC

CONTROL PANEL PARTS

30 Power unit 31 Panel sub assembly 33 Key xing plate 34 Screw; 3mm x 8mm 35 Screw; 3mm x 8mm

DOOR PARTS

56 Door stopper 63 Control unit cover

* 64 Door sub assembly * 65 Door frame assembly * 68 Latch head

69 spring

* 71 Choke cover

72 Sealer lm

73 Handle 100 Screw : 4mm x 10mm 101 Special screw 118 Screw; 4mm x 12mm 200 Door glass 202 Display unit 203 Control harness A 204 Key xing frame 205 Connector 206 Connector

Page 44

Page 45

[3] DOOR AND CONTROL PANEL PARTS FOR GLBM188HB/S

207

101

118

208

100

206

205

202

209

200

100

203

211

212

101

204

210

NOITPIRCSED.ON

207 Key sheet 208 FPC 209 Screw : 3mm x 6mm 210 Cushion

MISCELLANEOUS

88 Earth wire 89 Main wire harness

[2] DOOR AND CONTROL P ANEL PARTS FOR PLBMV188HC

Page 45

Page 46

NOITPIRCSED.ON

[3] DOO R AND CONTRO L PANE L PARTS FOR GLBM18 8 H B / S

CONTROL PANEL PARTS

30 Power unit 31 Panel [GLBM188HS] 31 Panel [GLBM188HB] 33 Key xing plate 34 Screw; 3mm x 8mm 35 Screw; 3mm x 8mm

DOOR PARTS

56 Door stopper 63 Control unit cover

* 64 Door sub assembly [GLBM188HB] * 64 Door sub assembly [GLBM188HS] * 65 Door frame [GLBM188HS] * 65 Door frame [GLBM188HB] * 68 Latch head

69 spring

* 71 Choke cover

72 Sealer lm 73 Handle [GLBM188HS]

73 Handle [GLBM188HB] 100 Screw : 4mm x 10mm 101 Screw : 4mm x 25mm 118 Screw; 4mm x 12mm 200 Door glass [GLBM188HS] 200 Door glass [GLBM188HB] 202 Display unit 203 Control harness A 204 Key xing frame 205 Connector 206 Connector 207 Key sheet [GLBM188HB] 207 Key sheet [GLBM188HS] 208 FPC 209 Screw : 3mm x 6mm 210 Cushion 211 Cushion 212 Cushion

MISCELLANEOUS

88 Earth wire

89 Main wire harness

Page 46

Page 47

[4] PACKING AND ACCESSORIES

NOITPIRCSED.ON

[4] PACKING AN D ACCESSO RIES

36 Damper assembly 38 Turntable 76 Accessory assembly 82 Cushion 84 Installation inst 85 Instruction book 86 Top template 87 Wall template 93 Mesh lter 95 Rack

GREASE FILTER(x2)

ACCESSORY ASSEMBLY

CUSHION

OPERATION MANUAL

WALL TEMPLATE

INSTALLATION INSTRUCTION

TOP TEMPLATE

TURNTABLE TRAY

TRAY PAD

TOP PAD

BOTTOM PAD

PACKING CASE

ACCESSORY HOLDER

EHP LABEL

WRAP COVER

Non-replaceable items

DOOR PROTECTOR

RACK PAD

PROTECTION SHEET

RACK

DAMPER ASSEMBLY

DOOR PAD

CABINET COVER

Page 47

Frigidaire GLBM188HB, GLBM188HS, PLBMV188HC Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual