Sharp KB-5121KS,KB-5121KK,KB-5121KW Service Manual

KB-5121KS/K/W

WARNING TO SERVICE PERSONNEL:

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. Sharp Electronics Corporation cannot be responsible, nor assume any liability, for injury or damage of any kind arising from the use of this manual.

Microwave ovens contain circuitry capable of producing very high voltage and current. Contact with the following parts may result in a severe, possibly fatal, electrical shock. (High Voltage Capacitor, High Voltage Power Transformer, High Voltage Rectifier and Heat sink etc., and Magnetron, High Voltage Harness etc..)

S15R256KB5121

KB-5121KS KB-5121KK KB-5121KW

COOK TOP

WITH

MICROWAVE DRAWER

MODELS

SERVICE MANUAL

TABLE OF CONTENTS

Page PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO

AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY ................... INSIDE FRONT COVER

BEFORE SERVICING ...................................................................................................... INSIDE FRONT COVER

WARNING TO SERVICE PERSONNEL ............................................................................................................... 1

MICROWAVE MEASUREMENT PROCEDURE..................................................................................................... 3

FOREWORD AND WARNING................................................................................................................................5

PRODUCT SPECIFICATIONS............................................................................................................................... 6

POWER CONNECTION .........................................................................................................................................7

ANTI-TIP DEVICE ................................................................................................................................................. 8

CONTROL LAYOUT ..............................................................................................................................................9

SCHEMATICS ..................................................................................................................................................... 10

TEST PROCEDURES.......................................................................................................................................... 13

TOUCH CONTROL PANEL ASSEMBLY ............................................................................................................. 24

COOK TOP/MICROWAVE DRAWER DISASSEMBLY ........................................................................................ 32

WIRINGDIAGRAMS ........................................................................................................................................... 39

PRINTED WIRING BOARDS ............................................................................................................................... 44

PARTS LIST ........................................................................................................................................................ 47

PACKING AND ACCESSORIES ......................................................................................................................... 55

This document has been published to be used for after sales service only. The contents are subject to change without notice.

SHARP ELECTRONICS CORPORATION

KB-5121KS pictured

KB-5121KS/K/W

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

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 SHARP ELECTRONICS CORPORATION immediately @1-800-237-4277.

If the unit operates with the door open, service person should 1) tell the user not to operate the oven and

2) contact SHARP ELECTRONICS CORPORATION and Food and Drug Administration's Center for Devices and Radiological Health immediately.

Service personnel should inform SHARP ELECTRONICS CORPORATION of any certified unit found with emissions in excess of 4mW/cm2. The owner of the unit should be instructed not to use the unit until the oven has been brought into compliance.

KB-5121KS/K/W

WARNING TO SERVICE PERSONNEL

Range units 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, Heating Elements, etc.. Read the Service Manual carefully and follow all instructions.

Before Servicing

1. Disconnect the power source, and then remove unit.

2. Open the drawer and keep it open.

3. Discharge high voltage capacitor.

WARNING: RISK OF ELECTRIC SHOCK.

DISCHARGE THE HIGH-VOLTAGE CAPACITOR BEFORESERVICING.

The high-voltage capacitor remains charged about 60 seconds after the oven has been switched off. Wait for 60 seconds and then short-circuit the connection of the highvoltage capacitor (that is the connecting lead of the highvoltage 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 source, and then remove neccessary covers.

2. Open the drawer and keep 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 source.

When the testing is completed,

1. Disconnect the power source, and then remove covers.

2. Open the drawer and keep it open.

3. Discharge high voltage capacitor.

4. Reconnect the leads to the primary of the power transformer.

5. Reinstall the covers.

6. Reconnect the power source.

7. Run the unit and check all functions.

After repairing

1. Reconnect all leads removed from components during testing.

2. Reinstall the covers.

3. Reconnect the power supply cord.

4. Run the oven and check all functions.

Microwave ovens should not be operated empty. To test for the presence of microwave energy within a cavity, place a cup of cold water on the oven tray, close the drawer 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 re-examine 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 a microwave leakage test should be carried out.

KB-5121KS/K/W

ATTENTION!!!

SAFE SERVICING PRACTICES

To avoid personal injury and/or property damage, it is important that Safe Servicing Practices be obser ved. The following are some limited examples of safe practices:

1. DO NOT attempt a product repair if you have any doubts as to your ability to complete it in a safe and satisfactory manner.

2. Before servicing or moving an appliance:

• Disconnect the power source by tripping the circuit breaker to the

OFF position, then disconnecting the wiring.

3. Never interfere with the proper operation of any safety device.

4. USE ONLY REPLACEMENT PARTS CATALOGED FOR THIS APPLIANCE. SUBSTITUTIONS MAY DEFEAT COMPLIANCE WITH SAFETY STANDARDS SET FOR HOME APPLIANCES.

5. GROUNDING : The standard color coding for safety ground wires is GREEN , or GREEN with YELLOW STRIPES . Ground leads are not to be used as current carrying conductors. It is EXTREMELY important that the service technician reestablish all safety grounds prior to completion of service. Failure to do so will create a hazard.

6. Prior to returning the product to service, ensure that:

• All electrical connections are correct and secure

• All electrical leads are properly dressed and secured away from sharp edges,

high-temperature components, and moving parts

• All non-insulated electrical terminals, connectors, heaters, etc. are adequately

spaced away from all metal parts and panels

• All safety grounds (both internal and external) are correctly and securely

connected

• All panels are properly and securely reassembled

KB-5121KS/K/W

MICROWAVE MEASUREMENT PROCEDURE

A. Requirements:

1) 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/cm2 at any point 5cm or more from the external surface of the oven.

2) Safety interlock switches: Primary interlock relay switch shall prevent microwave radiation emission in excess of the requirement as above mentioned. Secondary interlock relay and door sensing switch shall prevent microwave radiation emission in excess of 5 mW/cm2 at any point 5cm or more from the external surface of the oven.

B. 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 load of 275±15 ml (9.8 oz) of tap water initially at 20±5

C (68OF) 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.

3) Set the cooking control on Full Power Cooking Mode.

4) Close the drawer 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.

C. Leakage test:

Closed-drawer leakage test (microwave measurement):

1) Grasp the probe of the survey instrument and hold it perpendicular to the gap between the drawer 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 drawer 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 drawer, pull the drawer 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/cm2, and that the primary interlock switch/secondary interlock relay does turn the oven OFF before any door movement.

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

KB-5121KS/K/W

NOTES

KB-5121KS/K/W

SHARP ELECTRONICS CORPORATION

SHARP PLAZA, MAHWAH,

NEW JERSEY 07430-2135

SERVICE MANUAL

COOK TOP

WITH

MICROWAVE DRAWER

KB-5121KS / KB-5121KK / KB-5121KW

FOREWORD

This Manual has been prepared to provide Sharp Electronics Corp. Service Personnel with Operation and Service Information for the SHARP COOK TOP WITH MICROWAVE DRAWER, KB-5121KS/JK/ JW.

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.

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. (C) The door packing is not damaged. (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.

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.

PRODUCT DESCRIPTION

POWER CONNECTION ANTI-TIP DEVICE

SCHEMATICS

TEST PROCEDURE

TOUCH CONTROL PANEL

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE

WIRING DIAGRAM

PARTS LIST

KB-5121KS/K/W

ITEM DESCRIPTION

Power Output 1000 watts (IEC TEST PROCEDURE)

Operating frequency of 2450MHz

Cooking Cavity Dimensions Width 17-11/32

Height 5-7/8"

1.0 Cubic Feet Depth 17-1/8"

Control Complement Touch Navigation System

Clock ( 1:00 - 12:59 ) Timer (0 - 99 min. 99 seconds)

Microwave Power for Variable Cooking

Repetition Rate;

P-HI ................................................. Full power throughout the cooking time

P-90 .................................................................... approx. 90% of Full Power

P-80 .................................................................... approx. 80% of Full Power

P-70 .................................................................... approx. 70% of Full Power

P-60 .................................................................... approx. 60% of Full Power

P-50 .................................................................... approx. 50% of Full Power

P-40 .................................................................... approx. 40% of Full Power

P-30 .................................................................... approx. 30% of Full Power

P-20 .................................................................... approx. 20% of Full Power

P-10 .................................................................... approx. 10% of Full Power

P-0 ..................................................... No power throughout the cooking time

Kitchen Timer, Cooktop Warm, Stop/Clear, Start, Start, Minute Plus, OPEN, CLOSE.

Oven Cavity Light Yes

Safety Standard UL Listed FCC Authorized

DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J

MICROWAVE DRAWER SPECIFICATION

ITEM DESCRIPTION

Power Requirements 120 /208 - 120/240Volts / 46/50 Amperes

60 Hertz Single phase, 3 wire grounded

Cook Top Heating Elements Two 6" - 1200W

One 8" - 2000W

One 6"/9" - 1200/2400W One 6" - 100W

Control Complement Touch Navigation System

Clock ( 1:00 - 12:59 ) Timer (0 - 99 min. 99 seconds)

Kitchen Timer, Cooktop Warm, Stop/Clear,

COOK TOP SPECIFICATION

KB-5121KS/K/W

POWER CONNECTION

Note: This appliance must be properly grounded

Attention Installer: This appliance must be hard wired (direct

wired) into an approved junction box. A plug and receptacle is NOT permitted on this product.

SELECTING

208 OR 240 VOLT CONNECTION

This appliance can be set for 208V or 240V. The voltage setting for your appliance is pre-set at 240V from the factory. Follow these steps to change the voltage setting.

1 ecnailppa eht fo edis tfel eht no hctiws egatlov eht etacoL

(facing the front). See Figure 1.

2 Remove the screw and rotate the switch plate 180˚ as indicated

in the Figure 2.

3 Reinsert the switch plate and replace screw as indicated

in Figure 3. The voltage setting is indicated by the visible marking.

180˚

240V

208V

Screw

Figure 1

Figure 2 Figure 3

4-WIRE CONNECTION

When installing to a 4-wire electrical system, new construction, mobile home and recreational vehicle or when local codes do not permit grounding through neutral.

1 Disconnect the power supply.

In the junction box connect the appliance and residence cable

wires as shown in Figure 4.

Red wires

Green wires

White wires (nutral)

Black wires

Conduit connector

(not supplied)

Appliance

conduit & wires

Power supply

Figure 4

3-WIRE CONNECTION

When local codes permit connecting the cabinet-grounding conductor to the neutral (white) wire.

1 Disconnect the power supply.

In the junction box connect the appliance and residence cable wires as shown in Figure 5.

Red wires

White wires (nutral)

Black wires

Green wire

(ground)

Conduit connector

(not supplied)

Appliance

conduit & wires

Power supply

REINSTALL JUNCTION BOX COVER

Do not shorten the ﬂexible conduit. The conduit strain relief clamp (supplied by installer) must be securely attached to the junction box and the ﬂexible conduit must be securely attached to the clamp. If the ﬂexible conduit will not ﬁt with the junction box, do not install the appliance until a clamp of proper size has been obtained.

Figure 5

KB-5121KS/K/W

ADJUST ANTI-TIP BRACKET

Measure the thickness of the counter. See Figure 6. Locate the Anti-Tip Bracket on the backside of the appliance. See Figure 7. Loosen screws and adjust space between the glass cooktop and bracket to match the counter thickness plus 1/16”. See Figure 8. Tighten the screws to secure the bracket at the correct counter height dimension.

Measure thickness

Back of unit

Anti-Tip bracket

Lossen screws to adjust

countertop

thickness +1/16"

from bottom of

cooktop glass bracket

to top of Anti-Tip bracket

Figure 6

Figure 7

Figure 8

KB-5121KS/K/W

KB-5121KS

KB-5121KS/K/W

Schematic-Off Condition

NOTES:

1. Circuits / wire colors are subject to change without notice.

2. Terminal that is located on the right side on lamp sockets back view

must be connected to neutral wire.

HUMIDITY

SENSOR

NOISE SUPRESSION COIL

RESISTOR 470 kW 1/2W

LINE CROSS CAPACITOR 1.0 "F250V

LINE BYPASS CAPACITOR

0.0033 "F250V

LINE BYPASS CAPACITOR

0.0033 "F 250V

FUSE 20A

FAN MOTOR

OVEN LAMP

MONITOR SWITCH

PRIMARY INTERLOCK

RELAY

STIRRER MOTOR

CONTROL UNIT

MICROWAVE DRAWER

COOK TOP

SWITCHING POWER SUPPLY UNIT

INSIDE

OUTSIDE

CONTROL

RIGHT FRONT

SURFACE

ELEMENT

44aS2S1

H2/

P1/

CONTROL

L2/

PROTECTOR

CONTROL

INDICATOR LIGHT

HOT SURFACE LIGHT

HOT SURFACE

LIGHT

SWITCHES

H1/

CONTROL

LEFT REAR

SURFACE

ELEMENT

H1/

L1/

1b RR

1b2b

OVEN

THERMAL

CUT-OUT

THERMAL

CUT-OUT

SECONDARY INTELOCK SWITCH

MICROWAVE DRAWER

DOOR OPEN-CLOSE

MOTOR

DOOR

POSITION

SWITCH

FRONT

DOOR

POSITION

SWITCH

REAR

COOLING FAN

DC MOTOR

DOOR SENSING SWITCH

PROTECTOR

LEFT FRONT

SURFACE

ELEMENT

PROTECTOR

RIGHT REAR

SURFACE

ELEMENT

PROTECTOR

WARMER

SURFACE

ELEMENT

LOW VOLTAGE

TRANSFORMER

YLW

BLU

YLW

BLK

YLW

BRN

YLW

BLU

YLW

BLK

BLU

BRN

BLK

BLU

BLK

BLU

BLK

BLU

WHT

YLW

BLK

YLW

BRN

RED

WHT

P1/

BLK

YLW

WHT

RED

YLW*2

BLK

ORG

BLK

YLW

WHT

YLW*2

ORG

BLK

YLW

WHT

WHT *3

P1A/

RED

YLW

RED

YLW

RED

BRN

RED

WHT

RED

RED *3

BLK

BLK *3

P1B /

RED RED

BLK

YLW

RY8

COM

RED

ORG

RED

RY7

RY2

RY3

RY6

ORG

COM

N.O.

RED ORG

RED

WHT

WHT WHT

BLK

ORG

RED

BRN

HV RECTIFIE

MAGNETRO

CAPACITOR

1.00 "F AC 2300V

POWERTRANSFORMER

VOLTAGE SWITCH

RED

BRN

C5 C3

GRN

WHT

BLK

BRN

502

RED

GRN

WHT

RED

BLU

BLK

YLW

ORG

RED

GRY

BRN

BLK

WHT

RED

501

BRN

BLK

RED

WHT

BLK

YLW

WHT

YLW

P1/

YLW

RED

P1/

WHT

NOISE FILTER BOARD

BLK

RED

L1/

H1/

H2/

L2/

BLK

RED

BLK

KB-5121KS/K/W

COOK TOP SCHEMATIC (DETAIL)

INSIDE

OUTSIDE

CONTROL

RIGHT FRONT SURFACE ELEMENT

S2S1

H2/ 2

P1/ 4

CONTROL

L2/ P1

PROTECTOR

CONTROL

INDICATOR LIGHT

HOT SURFACE LIGHT

HOT SURFACE LIGHT SWITCHES

H1/ 4

CONTROL

LEFT REAR SURFACE ELEMENT

H1/ 4

L1/ P2

1b RR

1b2b

PROTECTOR

LEFT FRONT SURFACE ELEMENT

PROTECTOR

RIGHT REAR SURFACE ELEMENT

PROTECTOR

WARMER SURFACE ELEMENT

YLW YLW

BLU

YLW BLK

YLW BRN

YLW BLU

YLW

BLK

BLU

BRN

BLK BLU

WHT

WHT YLW

BLK

YLW

BRN

RED

WHT

P1/ 4

BLK YLW

WHT

RED

RED RED

YLW*2

BLK ORG

BLK

YLW

WHT

YLW*2

ORG

BLK

BLK YLW

WHT

WHT *3

P1A/ 4A

RED YLW

RED

YLW

RED RED

RED

BRN

RED WHT

RED

RED *3

BLK

BLK *3

P1B / 4

RED

BLK

YLW

WHT YLW

P1/ 4

YLW

RED

P1/ 4

WHT

L1/ P2

H1/ 4

H2/ 2

L2/ P1

BLK

RED

BLK

KB-5121KS/K/W

MICROWAVE DRAWER SCHEMATIC (DETAIL)

HUMIDITY

SENSOR

NOISE SUPRESSION COIL

RESISTOR 470 kW 1/2W

LINE CROSS CAPACITOR 1.0 " F250V

LINE BYPASS CAPACITOR

0.0033 "F250V

LINE BYPASS CAPACITOR

0.0033 "F 250V

FUSE 20A

FAN MOTOR

OVEN LAMP

MONITOR SWITCH

PRIMARY INTERLOCK

RELAY

STIRRER MOTOR

CONTROL UNIT

SWITCHING POWER SUPPLY UNIT

OVEN

THERMAL

CUT-OUT

THERMAL

CUT-OUT

SECONDARY INTELOCK SWITCH

MICROWAVE DRAWER

DOOR OPEN-CLOSE

MOTOR

DOOR

POSITION

SWITCH

FRONT

DOOR

POSITION

SWITCH

REAR

COOLING FAN

DC MOTOR

DOOR SENSING SWITCH

LOW VOLTAGE

TRANSFORMER

RY8

COM

RED

ORG

RED

RY7

RY2

RY3

RY6

ORG

COM

N.O.

RED ORG

RED

WHT WHT

BLK

ORG

RED

BRN

HV RECTIFIE

MAGNETRO

CAPACITOR

1.00 "F AC 2300V

POWER TRANSFORMER

VOLTAGE SWITCH

RED

BRN

C5 C3

GRN

WHT

BLK

BRN

502

RED

GRN

WHT

RED

BLU

BLK

YLW

ORG

RED

GRY

BRN

BLK

WHT

RED

501

BRN

BLK

RED

WHT

BLK

YLW

NOISE FILTER BOARD

BLK

RED

KB-5121KS/K/W

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT 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 and Keyboard Unit and Power Unit, and troubleshooting by unit replacement is described according to the symptoms indicated.

Before testing,

1) Disconnect the power source, and then disassemble as per "COOK TOP/MICROWAVE DRAWER DISASSEMBLY" page 32.

2) Open the drawer 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.

1. Keyboard Unit. NOTE ;

1) Check Keyboard unit connection before replacement.

2) Reconnect all leads removed from components during testing.

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

4) Reconnect the power source after the outer case is installed.

5) Run the oven and check all functions.

The following symptoms indicate a defective keyboard 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 Keyboard unit is defective.

1) Disconnect the power source, and then remove outer case.

2) Open the door and block it open.

3) Discharge high voltage capacitor.

4) Replace the Keyboard unit.

5) Reconnect all leads removed from components during testing.

6) Re-install the covers.

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

8) 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 Keyboard unit test (Procedure J) to determine if control unit is faulty.

2-1 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.

2-2 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 source, and then disassemble as per "COOK TOP/MICROWAVE DRAWER

DISASSEMBLY" page 32.

2) Open the drawer and block it open.

3) Discharge high voltage capacitor.

A TOUCH CONTROL PANEL ASSEMBLY TEST

KB-5121KS/K/W

1. Disconnect the power source, and then disassemble as per "COOK TOP/MICROWAVE DRAWER DISASSEMBLY" page 32.

2. Open the drawer 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 covers and check voltage between Pin Nos. 1 and 3 of the 2 pin connector (CN-B) on the power unit with an A.C. voltmeter. The meter should indicate 116 or 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.

RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS

RY1 Approx. 18V D.C. Oven lamp / Stirrer motor

RY2 Approx. 18V D.C. Power transformer

RY3 Approx. 18V D.C. Oven common relay RY4 Approx. 18V D.C. Top heater

RY5 Approx. 24V D.C. Fan motor (Microwave)

RY6 Approx. 24V D.C. Fan motor (Oven)

RY7 Approx. 24V D.C. Oven lamp (Oven) RY8 Approx. 24V D.C. Door lock motor (Oven)

RY9 Approx. 24V D.C. Convection motor

RY10 Approx. 24V D.C. Warmer (Cook top)

RY11 Approx. 24V D.C. Switching power supply RY-B Approx. 24V D.C. Bottom heater

RY-C Approx. 24V D.C. Convection heater

C RELAY TEST

4) Reconnect all leads removed from components during testing.

5) Re-install the covers.

6) Reconnect the power source after the outer case is installed.

7) Run the oven and check all functions.

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT TEST

B KEYBOARD UNIT TEST

1. Disconnect the power source, and then disassemble as per "COOK TOP/MICROWAVE DRAWER DISASSEMBLY" page 32.

2. Open the drawer and block it open.

3. Discharge high voltage capacitor.

4. If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the wire harness and connectors are making good contact between the control unit and the keyboard, verify that the door sensing switch operates properly; that is the contacts are closed when the door is closed and open when the door is open.

5. Remove the old keyboard unit and install the new keyboed unit (as the normal keyboard unit).

6. Reconnect the wire harness to the keyboard unit.

7. If the control unit responds by clearing with a beep when the stop/clear pad is touched, the old keyboard unit 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 keyboed unit is at fault.

8. Reconnect all leads removed from components during testing.

9. Re-install the covers.

10.Reconnect the power source after the outer case is installed.

11.Run the oven and check all functions.

KB-5121KS/K/W

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT TEST

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

(1) Place one cup of water in the center of the turntable tray in the oven cavity. (2) Close the door, touch the Stop/Clear (M) pad and touch the Defrost pad on the LCD. Then touch the

Steaks/Chops pad on the LCD. And touch the number pad 5 on the LCD. (Now, weight 0.5lb is set.)

And then touch the start pad on the LCD. (3) The oven is in Defrost cooking condition. (4) The oven will operate as follows

WEIGHT 1ST STAGE 2ND STAGE 3RD. STAGE

LEVEL TIME LEVEL TIME LEVEL TIME

0.5lb 60% 20sec. 40% 20sec. 30% 45sec.

(5) If improper operation is indicated, the control unit is probably defective and should be checked.

D DEFROST TEST

8. Reconnect all leads removed from components during testing.

9. Re-install the covers.

10. Reconnect the power source after the cabinets are installed.

11. Run the drawer and check all function.

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 source, and then disassemble as per "COOK TOP/MICROWAVE

DRAWER DISASSEMBLY" page 32.

2) Open the drawer and block it open.

3) Discharge high voltage capacitor.

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

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

6) Examine the touch control transformer with a tester for the presence of layer short-circuit (check the primary coil resistance which is approximately 60Ω ± 10%). If any abnormal condition is detected, replace the touch control transformer.

7) Reconnect all leads removed from components during testing.

8) Re-install the covers.

9) Reconnect the power source after the outer case is installed.

10) 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 source, and then disassemble as per "COOK TOP/MICROWAVE DRAWER

DISASSEMBLY" page 32.

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) Follow the troubleshooting guide given below for repair.

E PROCEDURES TO BE TAKEN WHEN THE FUSE ON THE PRINTED WIRING BOARD (PWB) IS

OPEN.

KB-5121KS/K/W

STEPS OCCURRENCE CAUSE OR CORRECTION

1 The rated AC voltage is not present between Check supply voltage and oven power cord.

Pin Nos. 1and 3 of the 2-pin connecter (CN-B).

2 The rated AC voltage is present at primary Touch control transformer or secondary circuit defective.

side of touch control transformer. Check and replace touch control transformer or power

unit .

8) Reconnect all leads removed from components during testing.

9) Re-install the covers.

10) Reconnect the power source after the cabinets are installed.

11) Run the oven and check all functions.

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT 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 95

F (35oC).

(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 conventional surface unit. Refer to the “INSTALLATION INSTRUCTIONS” of the operation manual.

(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.

(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) 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 (7.2 oz) 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 UPER MICROWAVE OVEN pad, pad, pad, START MINUTE PLUS pad and the

SENSOR LOAD pad on the LCD. And touch the number pad 4 once. Now, the oven is in the sensor

cooking condition, and "20BIT" and "MICRO" will appear in the display. (5) The oven will operate for the first 16 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 16 seconds, microwave energy is produced. If ERROR is displayed or the oven does not turn off, replace the AH sensor or check the control unit, refer to explanation below.

TESTING METHOD FOR AH 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 source, and then disassemble as per "COOK TOP/MICROWAVE DRAWER DISASSEMBLY" page 32.

2) Open the drawer and block it open.

3) Discharge high voltage capacitor.

4) Remove the AH sensor.

F AH SENSOR TEST

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Sharp KB-5121KS,KB-5121KK,KB-5121KW Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual