SHARP KB5121K, KB-5121KS, KB-5121KK, KB-5121KW Service Manual
SERVICE MANUAL
COOK TOP
WITH
MICROWAVE DRAWER
KB-5121KS
KB-5121KS/K/W
S15R256KB5121
KB-5121KS pictured
MODELS
KB-5121KK
KB-5121KW
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..)
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
SHARP ELECTRONICS CORPORATION
This document has been published to be used for after sales service only. The contents are subject to change without notice.
1
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.
(c) Before turning on microwave power for any service test or inspection within the microwave generating
compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment, integrity,
and connections.
(d) Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation and
transmission systems shall be repaired, replaced, or adjusted by procedures described in this manual before
the oven is released to the owner.
(e) A microwave leakage check to verify compliance with the 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.
2
WARNING TO SERVICE PERSONNEL
Range units contain circuitry capable of producing very high voltage and current, contact
with following parts
(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.
may result in a severe, possibly fatal, electrical shock.
KB-5121KS/K/W
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.
1
KB-5121KS/K/W
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
ATTENTION!!!
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.
2
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
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.
O
C (68OF) in the center of the oven cavity.
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.
3
KB-5121KS/K/W
NOTES
4
SERVICE MANUAL
KB-5121KS/K/W
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.
PRODUCT DESCRIPTION
POWER CONNECTION
ANTI-TIP DEVICE
SCHEMATICS
TEST PROCEDURE
TOUCH CONTROL PANEL
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
WIRING DIAGRAM
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
Δ
exposure, by themselves, or when they are damaged, loosened or
removed.
SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
PARTS LIST
5
KB-5121KS/K/W
COOK TOP 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,
MICROWAVE DRAWER SPECIFICATION
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
6
POWER CONNECTION
Red wires
Green wires
White wires (nutral)
Black wires
Conduit connector
(not supplied)
Appliance
conduit & wires
Power supply
Red wires
White wires (nutral)
Black wires
Green wire
(ground)
Conduit connector
(not supplied)
Appliance
conduit & wires
Power supply
KB-5121KS/K/W
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.
Figure 1
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.
2
In the junction box connect the appliance and residence cable
wires as shown in Figure 4.
Figure 4
3-WIRE CONNECTION
Screw
240V
Screw
180˚
208V
Figure 2 Figure 3
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.
When local codes permit connecting the cabinet-grounding conductor to the neutral (white) wire.
1 Disconnect the power supply.
2
In the junction box connect the appliance and residence cable
wires as shown in Figure 5.
Figure 5
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.
7
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
Figure 6
Back of unit
Figure 7
cooktop glass bracket
to top of Anti-Tip bracket
Anti-Tip bracket
Lossen screws to adjust
countertop
thickness +1/16"
from bottom of
Figure 8
8
KB-5121KS/K/W
KB-5121KS
9
KB-5121KS/K/W
N
WHT *3
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.
HOT SURFACE
LIGHT
SWITCHES
BLU
BLK
BLU
BLU
BLK
BLU
BLK
2b
1b
YLW
YLW
YLW
BLK
YLW
BLK
2b
1b2b
1b2b
1b RR
YLW
BLU
YLW
BRN
BRN
BLU
LR
RF
LF
WHT
L1
BLK
L
NOISE FILTER BOARD
RESISTOR 470 kW 1/2W
LINE CROSS CAPACITOR 1.0 "F250V
NOISE SUPRESSION COIL
MICROWAVE DRAWER
LINE BYPASS CAPACITOR
0.0033 "F250V
SECONDARY INTELOCK SWITCH
DOOR
BLK
SENSING
SWITCH
WHT
WHT
WHT
WHT
WHT
WHT
BRN
CAPACITOR
1.00 "F
AC 2300V
BRN
HUMIDITY
SENSOR
FAN MOTOR
STIRRER MOTOR
OVEN LAMP
BRN
FM
SM
OL
BRN
HV RECTIFIE
GRN
BLK
ORG
ORG
R
WHT
M1
M3
F3
F2
F1
C5 C3
RED
N.O.
RED
ORG
COM
WHT
MONITOR SWITCH
CONTROL
WHT
YLW
WHT
YLW
HOT SURFACE LIGHT
1a
PROTECTOR
2a
RED
WHT
LINE BYPASS CAPACITOR
0.0033 "F 250V
CONTROL UNIT
RY7
RY6
RY3
RY2
PRIMARY INTERLOCK
POWERTRANSFORMER
RED
VOLTAGE SWITCH
BLK
MAGNETRO
N
Schematic-Off Condition
COOK TOP
BLK
L1/
P2
P
RED
RED
ORG
ORG
RED
CONTROL
YLW
LEFT FRONT
SURFACE
ELEMENT
PROTECTOR
RED
L2
L
THERMAL
CUT-OUT
THERMAL
CUT-OUT
COM
BLK
BLK
1a
2a
RED
OVEN
MG
4
4
2
WHT
2
P1
RED
2
ORG
YLW
H1/
P1/
H2/
L2/
RED
RED
GRN
502
502
1
WHT
B3
B1
WHT
L1/
P2
P
YLW
INDICATOR LIGHT
WHT
501
1
502
3
RED
RED
E1
E2
N2
N3
N4
N5
M6
M7
BRN
M4
M5
BLK
P1/
4
WARMER
SURFACE
ELEMENT
2
1a
PROTECTOR
2a
YLW
RED
501
3
SWITCHING POWER SUPPLY UNIT
RED
MICROWAVE DRAWER
DOOR OPEN-CLOSE
MOTOR
RED
N1
ORG
DM
BLU
YLW
BLK
DOOR
POSITION
SWITCH
FRONT
GRY
DOOR
POSITION
SWITCH
REAR
BLK
BLK
A6
LOW VOLTAGE
TRANSFORMER
A4
A1
A2
H1/
4
P1/
4
ELEMENT
2
BRN
2
L2/
P1
RELAY
BLK
BLK
YLW*2
YLW
LEFT REAR
SURFACE
H2/
FUSE
20A
RED
BRN
BRN
BLK
RED
RED
INSIDE
1a
2a
RED
YLW
44aS2S1
P1B /
4
BRN
2
P1
BLK *3
CONTROL
YLW
INDICATOR LIGHT
RED
RED
RED *3
L1
L2
RED
BLK
ORG
BLK
CONTROL
4
WHT
YLW
YLW
WHT
YLW
4
RIGHT REAR
SURFACE
ELEMENT
2
1a
PROTECTOR
2a
BLK
P1
RED
YLW
L1/
P2
P2
WHT
P
YLW*2
H1/
P1A/
4A
YLW
RIGHT FRONT
SURFACE
ELEMENT
P1/
OUTSIDE
PROTECTOR
YLW
H2/
2
L2/
RED
WHT
L2
RED
RED
RED
BLK
BLK
L1
YLW
RY8
C7
COOLING FAN
DC MOTOR
DM
E3
BLK
CONTROL UNIT
10
COOK TOP SCHEMATIC (DETAIL)
KB-5121KS/K/W
BLK
BLK *3
BLK
L1
ORG
CONTROL
P2
BLK
YLW
L1/
P2
CONTROL
YLW
RED
WHT
S2S1
4
4a
P
YLW*2
H1/
4
WHT
P1B /
4
RED
YLW
P1A/
4A
RIGHT FRONT
SURFACE
ELEMENT
YLW
YLW
INSIDE
OUTSIDE
P1/
4
WHT
YLW
BLK
YLW
RIGHT REAR
SURFACE
ELEMENT
P1/
4
WARMER
SURFACE
ELEMENT
2
1a
2
INDICATOR LIGHT
1a
PROTECTOR
PROTECTOR
1a
PROTECTOR
YLW
2a
BRN
2a
2a
H2/
2
BLK
L2
RED
RED
RED
WHT
RED
RED *3
RED
RED
2
P1
L2/
P1
YLW
L2
RED
RED
RED
N
WHT *3
BLK
ORG
BLK
BLK
BLK
BLU
BLK
BLU
BLK
BLU
BLU
HOT SURFACE
LIGHT
SWITCHES
L1/
P2
CONTROL
L1/
P2
CONTROL
2b
2b
P
YLW
H1/
4
BLK
BLK
YLW
P1/
4
YLW
LEFT FRONT
SURFACE
ELEMENT
2
INDICATOR LIGHT
1a
PROTECTOR
P
P1/
4
WHT
YLW
LEFT REAR
SURFACE
ELEMENT
2
1a
YLW*2
H1/
4
WHT
YLW
PROTECTOR
YLW
HOT SURFACE LIGHT
1b RR
YLW
BRN
1b2b
YLW
BLU
1b2b
YLW
BLK
1b
YLW
YLW
BRN
BLU
LR
BLK
YLW
WHT
2a
BRN
2a
H2/
2
RED
L2/
P1
RED
RED
L2
H2/
L2/
2
P1
RED
WHT
RF
WHT
LF
11
KB-5121KS/K/W
MICROWAVE DRAWER SCHEMATIC (DETAIL)
L1
BLK
L
RESISTOR 470 kW 1/2W
LINE CROSS CAPACITOR 1.0 " F250V
NOISE SUPRESSION COIL
LINE BYPASS CAPACITOR
0.0033 "F250V
SECONDARY INTELOCK SWITCH
HUMIDITY
SENSOR
FAN MOTOR
OVEN LAMP
BRN
DOOR
SENSING
SWITCH
FM
SM
OL
BRN
GRN
BLK
ORG
RED
ORG
BRN
WHT
WHT
WHT
WHT
WHT
WHT
CAPACITOR
1.00 "F
AC 2300V
BLK
BRN
STIRRER MOTOR
NOISE FILTER BOARD
LINE BYPASS CAPACITOR
0.0033 "F 250V
WHT
M1
M3
F3
F2
RED
ORG
F1
C5 C3
N.O.
COM
RY7
RY6
RY3
RY2
MONITOR SWITCH
POWER TRANSFORMER
RED
BLK
FUSE
20A
CONTROL UNIT
PRIMARY INTERLOCK
RELAY
RED
VOLTAGE SWITCH
BRN
BRN
RED
RED
ORG
ORG
RED
L
CUT-OUT
CUT-OUT
COM
RED
2
OVEN
THERMAL
MG
THERMAL
GRN
RED
WHT
501
1
501
3
SWITCHING POWER SUPPLY UNIT
RED
502
502
3
502
1
RED
WHT
E1
B3
RED
RED
E2
MICROWAVE DRAWER
DOOR OPEN-CLOSE
MOTOR
RED
N1
ORG
N2
DM
BLU
N3
YLW
N4
N5
BLK
DOOR
POSITION
SWITCH
FRONT
M6
GRY
M7
BRN
DOOR
POSITION
SWITCH
REAR
M4
BLK
M5
BLK
A6
LOW VOLTAGE
TRANSFORMER
A4
A1
A2
COOLING FAN
DC MOTOR
YLW
RY8
C7
CONTROL UNIT
DM
E3
BLK
HV RECTIFIE
WHT
MAGNETRO
N
B1
WHT
R
12
TEST PROCEDURES
KB-5121KS/K/W
PROCEDURE
LETTER
A 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 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.
COMPONENT TEST
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KB-5121KS/K/W
TEST PROCEDURES
PROCEDURE
LETTER
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.
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.
C RELAY TEST
COMPONENT 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. 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
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TEST PROCEDURES
KB-5121KS/K/W
PROCEDURE
LETTER
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.
D DEFROST 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
(3) The oven is in Defrost cooking condition.
(4) The oven will operate as follows
(5) If improper operation is indicated, the control unit is probably defective and should be checked.
COMPONENT TEST
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.
WEIGHT 1ST STAGE 2ND STAGE 3RD. STAGE
LEVEL TIME LEVEL TIME LEVEL TIME
0.5lb 60% 20sec. 40% 20sec. 30% 45sec.
E 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 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.
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KB-5121KS/K/W
TEST PROCEDURES
PROCEDURE
LETTER
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.
F AH 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 95
(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.
COMPONENT TEST
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
o
F (35oC).
unit .
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.
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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.
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