Sharp KB-6524PS User manual

1
KB-6525PS
KB-6525PK
KB-6525PW
In the interest of user-safety the unit should be restored to its original condition and only parts identical to those specified should
be used.
WARNINGTO 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. (HighVoltage Capacitor, High Voltage
PowerTransformer, High Voltage Rectifier, Heat sink, Magnetron, and HighVoltage Harness etc..)
S19M304KB6524
KB-6525PS/PK/PW
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.................................................................................................................3
MICROWAVE MEASUREMENT PROCEDURE.....................................................................................................4
FOREWORD AND WARNING ...............................................................................................................................5
PRODUCT SPECIFICATIONS...............................................................................................................................6
SCHEMATICS......................................................................................................................................................10
TEST PROCEDURES..........................................................................................................................................11
MICROWAVE DRAWER DISASSEMBLY.............................................................................................................22
WIRING DIAGRAMS............................................................................................................................................28
PARTS LIST .........................................................................................................................................................29
PACKING AND ACCESSORIES..........................................................................................................................34
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-6525PS pictured
KB-6524PS pictured
KB-6524PS/PK/PW

2
KB-6524PS
KB-6524PK
KB-6524PW
PRECAUTIONS TO BE OBSERVED BEFORE AND
DURINGSERVICINGTOAVOIDPOSSIBLEEXPOSURE
TO EXCESSIVE MICROWAVE ENERGY
(a) Do not operate or allow the oven to be operated with the door open.
(b) Makethefollowingsafetychecksonallovens tobe servicedbeforeactivatingthemagnetronorothermicrowave
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 compart-
ments, 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 Measure-
ment 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.
Servicepersonnel should inform SHARPELECTRONICSCORPORATIONof anycertifiedunit foundwith
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.

3
KB-6525PS
KB-6525PK
KB-6525PW
WARNINGTO SERVICE PERSONNEL
Microwave Oven 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 supply cord , and then
remove cabinet.
2. Open the drawer and keep it open.
3. Discharge high voltage capacitor.
WARNING: RISK OF ELECTRIC SHOCK.
DISCHARGETHE 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 short-circuit 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
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 supply cord.
When the testing is completed,
1. Disconnect the power supply cord, 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 supply cord.
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)
carefullycheckthatthewaterisnowhot.Ifthewaterremains
coldcarryoutBeforeServicingprocedureandre-examine
the connections to the component being tested.
When all service work is completed and the oven is fully
assembled,themicrowavepoweroutputshouldbechecked
and a microwave leakage test should be carried out.

4
KB-6524PS
KB-6524PK
KB-6524PW
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/cm2at 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/cm2at 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±5O 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.
Theplacingofthisstandardloadintheoven is important not onlytoprotecttheoven, butalsotoinsurethatanyleakage
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.

5
KB-6525PS
KB-6525PK
KB-6525PW
SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
SERVICE MANUAL
MICROWAVE DRAWERS
KB-6524PS / KB-6524PK / KB-6524PW
KB-6525PS / KB-6525PK / KB-6525PW
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp.
Service Personnel and Service Information for the MICROWAVE
DRAWERS.
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
Certaininitialpartsareintentionallynotgroundedandpresent
a risk of electrical shock only during servicing. Service
personnel - Do not contact the following parts while the ap-
pliance is energized;
HighVoltage Capacitor,PowerTransformer, 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.
Allthepartsmarked“ ”onpartslistmaycauseunduemicrowave
exposure, by themselves, or when they are damaged, loosened
or removed.
PRODUCT DESCRIPTION
SCHEMATICS
TEST PROCEDURE
MICROWAVE DRAWER
DISSASSEMBLY AND
ADJUSTMENT PROCEDURE
WIRING DIAGRAM
PARTS LIST
∆

6
KB-6524PS
KB-6524PK
KB-6524PW
ITEM DESCRIPTION
Power Requirements 120 Volts
14.5 Amperes, 1000 watts
60 Hz
Single phase, 3 wire grounded
Power Output 1000 watts (IEC TEST PROCEDURE)
Operating frequency of 2450MHz
Cooking Cavity Dimensions KB6524 Width 17-11/32 KB6525 Width 17-11/32
Height 7-7/8" Height 7-7/8"
1.2 Cubic Feet Depth 16-1/2" Depth 16-1/2"
Outside Dimensions KB6524 Width 23-7/8" KB6525 Width 30"
Height 15-9/32" Height 15-9/32"
(Including drawer handle) Depth 26-1/16" Depth 26-1/16"
Packing Case Dimensions KB6524 Width 27-11/16" KB6525 Width 34-1/2"
Height 21-1/2" Height 21-1/2"
Depth 29-1/16" Depth 29-1/16"
(Packed unit) 86 Lbs 92 Lbs
Control Complement Touch Control 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
START/MINUTE PLUS pad, Defrost pad, Number selection pad, Keep-warm
pad, Power Level pad, Timer/Clock pad, Stop/Clear pad, Sensor Reheat,
Sensor Popcorn, Sensor Cook, Open pad, Close pad, Setup/Custom Help,
On/Off, Control Lock, Reheat, Soften, Melt, Beverage center and Warm.
Oven Cavity Light Yes
Safety Standard UL Listed FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J
MICROWAVE DRAWER SPECIFICATION

7
KB-6525PS
KB-6525PK
KB-6525PW
GROUNDING INSTRUCTIONS
This oven is equipped with a three prong grounding plug.It must be
pluggedintoawallreceptaclethatisproperlyinstalledandgrounded
inaccordance with theNationalElectricalCodeand local codesand
ordinances.
Intheeventofanelectricalshortcircuit,groundingreducestheriskof
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 electrical requirements are a 120 volt 60 Hz, AC only, 15 or
20 amp. fused electrical supply. It is recommended that a separate
circuit serving only this appliance be provided.When installing this
appliance, observe all applicable codes and ordinances.
Where a two-pronged wall-receptacle is encountered, it is the
personal responsibility and obligation of the customer to contact a
qualified electrician and have it replaced with a properly grounded
three-pronged wall receptacle or have a grounding adapter prop-
erly grounded and polarized. If an extension cord must be used,
it should be a 3-wire, 15 amp. or higher rated cord. Do not drape
over a counter top or table where it can be pulled on by children or
tripped over accidentally.
NOTE:
Thedirected featuresaredisabledafter one minutewhen theoven isnot in use.Thesefeaturesareautomatically enabled
when the door is opened and closed or the STOP/ CLEAR pad is pressed.
3-Pronged
Plug
Grounded
Receptacle Box
Grounding Pin
3-Pronged Receptacle
KB-6524/6525P
(Colors may vary)
2
18
5
4
3
7
6
1Control panel
2Waveguide cover DO NOT REMOVE
3Microwave Drawer Menu Label
4Drawer sealing surfaces
5Drawer light
6Microwave Drawer guides
7Vent
8Name plate: open the Microwave Drawer fully. The label
is beyond the back wall of the microwave cavity facing
up from the flat surface.
CAUTION: DO NOT UNDER ANY CIRCUMSTANCES
CUT OR REMOVETHE ROUND GROUND-
INGPRONGFROMTHISPLUG. ALSO,"DO
NOT USE AN EXTENSION CORD".
OVEN DIAGRAM
GENERAL INFORMATION
KEY SHEET

8
KB-6524PS
KB-6524PK
KB-6524PW OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions dur-
ing oven operation.
OFF CONDITION
Closing the drawer 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. (Page 10).
1. Thedisplaywillshowflashing"EnjoyYourDrawerTouch
Clear and Touch Clock".
Tosetanyprogramorsettheclock,youmustfirsttouch
the STOP/CLEAR pad.The display will clear, and " : "
will appear.
COOKING CONDITION
Program desired cooking time by touching the NUMBER
pads. Program the power level by touching the POWER
LEVEL pad and then a Number pad.
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 Page 10)
RELAY CONNECTED COMPONENTS
RY-1 Oven lamp/stir fan motor/fan motor
RY-2 Power transformer
RY-3 Stirrer motor
RY-4 Fan motor
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
2370 volts A.C. on the high voltage winding.
3. The filament winding voltage heats the magnetron
filamentand theH.V.windingvoltageis senttoa 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 drawer is opened during a cook cycle, the
monitorswitch,doorsensingswitch,secondaryinterlock
switch, relay (RY1) and primary interlock relay are
activatedwiththefollowingresults.Thecircuitstothestir
fan motor, the cooling fan motor, and the high voltage
componentsarede-energized,theovenlampremainson,
and the digital read-out displays the time still remaining
in the cook cycle when the door was opened.
7. Themonitor switchelectricallymonitorsthe operationof
the secondary interlock switch and secondary interlock
relay and is mechanically associated with the drawer so
that it will function in the following sequence.
8. When the drawer opens from the closed position, the
primary interlock relay (RY2) and secondary interlock
switch open their contacts. And contacts of the relay
(RY1) remainsclosed.Thenthemonitorswitchcontacts
close.
9. When the drawer 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 drawer
is opened, the closing of the monitor switch contacts will
form a short circuit through the fuse, secondary interlock
switch, relay (RY1) and secondary interlock relay (RY2),
causing the fuse to blow.
POWER LEVEL P-0TO P-90 COOKING
When Variable Cooking Power is programmed, the 120
voltsA.C.issuppliedtothepowertransformerintermittently
through the contacts of relay (RY-2) which is operated by
the control unit within a 32 second time base. Microwave
power operation is as follows:
VARI-MODE ON TIME OFF TIME
Power 10(P-HI) 32 sec. 0 sec.
(100% power)
Power 9(P-90) 30 sec. 2 sec.
(approx. 90% power)
Power 8(P-80) 26 sec. 6 sec.
(approx. 80% power)
Power 7(P-70) 24 sec. 8 sec.
(approx. 70% power)
Power 6(P-60) 22 sec. 10 sec.
(approx. 60% power)
Power 5(P-50) 18 sec. 14 sec.
(approx. 50% power)
Power 4(P-40) 16 sec. 16 sec.
(approx. 40% power)
Power 3(P-30) 12 sec. 20 sec.
(approx. 30% power)
Power 2(P-20) 8 sec. 24 sec.
(approx. 20% power)
Power 1(P-10) 6 sec. 26 sec.
(approx. 10% power)
Power 0(P-0) 0 sec. 32 sec.
(0% power)
Note: TheON/OFFtimeratiodoesnotcorrespondwiththe
percentageofmicrowavepower,becauseapprox.2
seconds are needed for heating of the magnetron
filament.

9
KB-6525PS
KB-6525PK
KB-6525PW
SENSOR COOKING CONDITION
Using the SENSOR function, food is cooked without figur-
ing 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
timeandpowerlevelneededforbestresults. Whenthefood
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.
Thetimeofsupplementarycookingisdeterminedbyexperi-
ment 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.
MICROWAVE
2.Heat Potatoes. Moisture and humidity is emitted very
rapidly. You can smell the aroma as it cooks.
MICROWAVE
AH SENSOR
3.Sensor detects moisture and humidity and calculates
cooking time and variable power.
Cooking Sequence.
1. Touch one of the SENSOR pads.
NOTE: The oven should not be operated on sensor
immediately after plugging in the unit. Wait two
minutes before cooking on SENSOR.
2. The coil of shut-off relay (RY-1) is energized, but the
power transformer is not turned on.
3. After about 16 seconds, the cook relay (RY-2) is
energized. The power transformer is turned on,
microwaveenergyisproducedandfirststageisstarted.
The 16 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 drawer or
touch STOP/CLEAR pad.
4. When the sensor detects the vapor emitted from the
food,thedisplayswitchesovertotheremainingcooking
time and the timer counts down to zero.
At this time, the drawer may be opened to stir, turn or
season food.
5. Whenthetimerreacheszero,anaudiblesignalsounds.
Theshut-offrelayandcookrelayarede-energizedand
the power transformer, oven lamp, etc.are turned off.
6. OpeningthedrawerortouchingtheSTOP/CLEARpad,
the time of the day will reappear on the display and the
oven will revert to an OFF condition. When the timer
reaches zero, an audible signal sounds.

10
KB-6524PS
KB-6524PK
KB-6524PW SCHEMATIC (OFF CONDITION)
ＳＭ
ＯＬ
ＦＭ
ＲＹ１
ＲＹ２
ＲＹ３
HUMIDITY
SENSOR
NOISESUPRESSIONCOIL
RESISTOR 470kΩ1/2W
LINECROSSCAPACITOR1.0μF275V
LINEBYPASSCAPACITOR
0.0033μF250V LINEBYPASSCAPACITOR 0.0033μF250V
FUSE
20A
FANMOTOR
OVENLAMP
MONITORSWITCH
PRIMARYINTERLOCKRELAY
RECTIFIER MAGNETRON
POWERTRANSFORMAR
CAPACITOR
1.00μF
AC2300V
STIRRER
MOTOR
Ｌ
Ｎ
Ａ７Ａ５
Ａ１ Ａ３
C
１
C
５
ＣＮ２０１ 1
ＣＮ１０１ ３ ＣＮ１０１
１
ＣＮ２０１ 5
〜
CONTROLUNIT
Ｎ１
Ｎ２
Ｎ３
Ｎ４
Ｎ５
Ｎ６
Ｎ７
Ｎ８
SWITCHINGREGULATOR
OVEN THERMAL CUT-OUT 
MG THERMAL CUT-OUT 
〜 〜〜
SECONDARYINTELOCKSWITCH
ＤＭ
MICROWAVEDRAWER DOOROPEN-CLOSE MOTOR
ＲＹ４
〜
DOOR SENSING SWITCH
C４
C２
Ｆ１
Ｆ２
Ｆ３
〜
〜
〜
〜〜
〜

11
KB-6525PS
KB-6525PK
KB-6525PW
TEST PROCEDURES
PROCEDURE
LETTER COMPONENTTEST
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,
Keyboard 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 "MICROWAVE DRAWER
DISASSEMBLY" page 22.
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 covers.
4) Reconnect the power supply cord after the covers are 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 supply cord, and then remove covers.
2) Open the drawer 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 covers are 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 B) 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 supply cord, and then disassemble as per "MICROWAVE DRAWER
DISASSEMBLY" page 22.
2) Open the drawer and block it open.
3) Discharge high voltage capacitor.
A TOUCH CONTROL PANEL ASSEMBLYTEST
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc.Therefore,

12
KB-6524PS
KB-6524PK
KB-6524PW
C RELAYTEST
4) Reconnect all leads removed from components during testing.
5) Re-install the covers.
6) Reconnect the power supply cord after the covers are installed.
7) Run the oven and check all functions.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENTTEST
B KEY UNITTEST
1. Disconnect the power supply cord, and then remove outer case.
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. Ensurethattheseleadsremainisolatedfromothercomponentsandovenchassisbyusinginsulation
tape.
6. After that procedure, re-connect the power supply cord.
7. Remove the outer case and check voltage between Pin Nos.5 and 7 of the 4 pin connector (CN-A)
on the power unit with an A.C. voltmeter.
The meter should indicate 120 volts, if not check oven circuit.
RY1, RY2, RY3 and RY4 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 Checkdiodewhichisconnectedtotherelaycoil.Ifdiodeisgood,
control unit is defective.
RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS
RY1 Approx.26V D.C. Oven lamp / Common
RY2 Approx.25V D.C. Power transformer
RY3 Approx.26V D.C. Stirrer motor
RY4 Approx.26V D.C. Fan motor
RY5 Approx.26V D.C. Switching regurator for drawer motor
8.Disconnect the power supply cord, and then remove outer case.
9.Open the door and block it open.
10.Discharge high voltage capacitor.
11.Reconnect all leads removed from components during testing.
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 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 drawer is closed and open when the
drawer 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 drawer sensing switch is closed
(either closethe drawer orshort thedoor sensingswitch connecter).
Use the Key unit matrix indicated on the control panel schematic
and place a jumper wire between the pins that correspond to the
STOP/CLEAR pad making momentary contact. If the control unit
responds by clearing with a beep the key 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 key pad is at fault.
5. Reconnect all leads removed from components during testing.
6. Re-install the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.

13
KB-6525PS
KB-6525PK
KB-6525PW
WARNING : The oven should be fully assembled before following procedure.
(1) Place one cup of water in the center of the tray in the oven cavity.
(2) Close the drawer, touch the Defrost pad.Then select Steaks/Chops by touching the number pad
2. And touch the number pad 5. (Now, weight 0.5lb is set.) And then touch the start pad.
(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 DEFROSTTEST
E PROCEDURESTO BETAKEN WHENTHE FUSE ONTHE PRINTED WIRING BOARD (PWB) IS OPEN.
12.Re-install the outer case (cabinet).
13.Reconnect the power supply cord after the outer case is installed.
14.Run the oven 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 supply cord.
2) Remove the outer case cabinet.
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 151.6Ω± 10%).If any abnormal condition is
detected, replace the touch control transformer.
8) Reconnect all leads removed from components during testing.
9) Re-install the outer case (cabinet).
10) Reconnect the power supply cord after the outer case is 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 outer case cabinet.
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.
STEPS OCCURRENCE CAUSE OR CORRECTION
1 The rated AC voltage is not present between Check supply voltage and oven power cord.
Pin Nos.5 and 7 of the 4-pin connecter (CN-A).
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
.
9) Disconnect the power supply cord, and then remove outer case.
10) Open the door and block it open.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENTTEST

14
KB-6524PS
KB-6524PK
KB-6524PW
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 95οF (35οC).
(3) The unit should not be installed in any area where heat and steam are generated.The unit should not be
installed,forexample,nexttoaconventionalsurfaceunit.Refertothe“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 drawer.
(4) Touch theTIMER/CLOCK pad once, the POWER LEVEL pad twice and the START pad once.And touch
the number pad 1 once and the number pad 4 once. Now, the oven is in the sensor cooking condition,
and "AH20" and "ON" 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.If the oven stops after 5 minutes and no ERROR code is displayed, then the AH sensor
is normal. Check other parts except the AH sensor.
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 supply cord, and then disassemble as per "MICROWAVE DRAWER
DISASSEMBLY" page 22.
(2) Open the drawer and block it open.
(3) Discharge high voltage capacitor.
(4) Remove the AH sensor.
(5) Install the new AH sensor.
(6) Reconnect all leads removed from components during testing.
(7) Re-install the covers.
(8) Reconnect the power supply cord after the covers are installed.
(9) Reconnect the oven to the power supply and check the sensor cook operation as follows:
9-1. Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.
F AH SENSORTEST
Checking the initial sensor cooking condition
11) Discharge high voltage capacitor.
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.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENTTEST

15
KB-6525PS
KB-6525PK
KB-6525PW
TEST PROCEDURES
PROCEDURE
LETTER COMPONENTTEST
9-2. Place the container on the center of tray in the oven cavity.
9-3. Close the drawer.
9-4. Touch the TIMER/CLOCK pad once, the POWER LEVEL pad twice and the START pad once.And
touch the number pad 1 once and the number pad 4 once.
9-5. The control panel is in automatic Sensor operation.
9-6. The oven turns off automatically, and the time for detecting moisture will be displayed.
If new sensor does not operate properly, the problem is with the control unit, and refer to explanation be-
low. CHECKING CONTROL UNIT
(1) Disconnect the power supply cord, and then disassemble as per "MICROWAVE DRAWER
DISASSEMBLY" page 22.
(2) Open the drawer 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:
9-1. Close the door.Touch the TIMER/CLOCK pad once, the POWER LEVEL pad twice and the START
pad once.And touch the number pads 1 once and the number pad 4 once.
9-2.The control panel is in the sensor cooking operation.
9-3. Afterapproximately25seconds,pushplungerofselectswitchformorethan3seconds.Thiscondition
is same as judgement by AH sensor.
9-4. 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 AH sensor is probably defective.
(10) Disconnect the power supply cord, and then remove covers.
(11) Open the drawer 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 covers.
(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
Plunger
NC
NO
COM
COM NO
NC
R3 R4
R1
R2
1
2
3
F-1
F-2
F-3
To connector (F)
on Control Unit.
CONNECTOR

16
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KB-6524PW
2. Open the drawer and keep it open.
3. To discharge high voltage capacitor, wait for 60 seconds.
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. Reassemble the unit.
8. Reconnect the power supply cord.
9. Run the oven and check all functions.
MICROWAVE OUTPUT POWER
The following test procedure should be carried out with the microwave oven in a fully assembled condition.
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: 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 POWER 10(HIGH) 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 28οto
54οF (16οto 30οC) 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.
G MAGNETRON ASSEMBLYTEST
1. Disconnect the power supply cord.
2. Open the drawer and keep it open.
3. To discharge high voltage capacitor, wait for 60 seconds.
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 293οF(145οC).
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. Reassemble the unit.
7. Reconnect the power supply cord.
8. Run the unit and check all functions.
CAUTION: IFTHETHERMAL CUT-OUTINDICATESANOPENCIRCUITATROOMTEMPERATURE,
REPLACE THERMAL CUT-OUT.
H THERMAL CUT-OUTTEST
1. Disconnect the power supply cord.
Refer to the disassembly instructions found on Page 22.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENTTEST

17
KB-6525PS
KB-6525PK
KB-6525PW
I SECONDARY INTERLOCK SWITCHTEST
STOP SWITCH
1. Disconnect the power supply cord.
2. Open the drawer and keep it open.
3. To discharge high voltage capacitor, wait for 60 seconds.
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 drawer open and a closed
circuit with the drawer closed.If improper operation is indicated, replace the stop switch.
5. Reconnect all leads removed from components during testing.
6. Reassemble the unit.
7. Reconnect the power supply cord.
8. Run the oven and check all functions.
NOTE: If the stop 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.
J STOP SWITCH TEST
K MONITOR SWITCHTEST
1. Disconnect the power supply cord.
2. Open the drawer and keep it open.
3. To discharge high voltage capacitor, wait for 60 seconds.
4. Before performing this test, make sure that the secondary interlock switch is operating, according to
the above SwitchTest Procedure.Disconnect the wire lead from the monitor switch (COM) terminal.
Check the monitor switch operation by using the ohmmeter as follows.When the drawer 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 drawer 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 and both the monitor switch,
plus fuse will need to be replaced. 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. Reassemble the unit.
7. Reconnect the power supply cord.
8. Run the oven and check all functions.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENTTEST
1. Disconnect the power supply cord.
2. Open the drawer and keep it open.
3. To discharge high voltage capacitor, wait for 60 seconds.
4. Isolatetheswitchandconnecttheohmmetertothecommon(COM.)andnormally
open (NO) terminal of the switch.The meter should indicate an open circuit with
thedraweropen and a closed circuit with the drawerclosed.If improper operation
is indicated, replace the secondary interlock switch.
5. Reconnect all leads removed from components during testing.
6. Reassemble the unit.
7. Reconnect the power supply cord.
8. Run the oven and check all functions.
Screw Driver
Ohmmeter

18
KB-6524PS
KB-6524PK
KB-6524PW
TEST PROCEDURES
PROCEDURE
LETTER COMPONENTTEST
M POWERTRANSFORMERTEST
1. Disconnect the power supply cord.
2. Open the drawer 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 82 ohms (+ or - 10%); the resistance of the filament coil should be less than 1
ohm.
5. Reconnect all leads removed from components during testing.
6. Reassemble the unit.
7. Reconnect the power supply cord.
8. Run the oven and check all functions.
CAUTION:
(HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO
MEASURE THE FILAMENT AND HIGH VOLTAGE.)
2. Open the drawer and block it open.
3. To discharge high voltage capacitor, wait for 60 seconds.
4. Ifthemonitorfuseisblownwhenthedrawerisopened,checktheprimaryinterlockswitch,secondary
interlockswitchandmonitorswitchaccordingtothe "TESTPROCEDURE"forthose switchesbefore
replacing the blown monitor fuse.
CAUTION: BEFOREREPLACINGABLOWNMONITORFUSE,TESTTHESECONDARYINTERLOCK
SWITCH, STOP SWITCH AND MONITOR SWITCH FOR PROPER OPERATION.
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-BA018/KIT, 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. Reassemble the unit.
7. Reconnect the power supply cord.
8. Run the oven and check all functions.
L BLOWN MONITOR FUSETEST
1. Disconnect the power supply cord.

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KB-6525PW
(1)Structure of Humidity Sensor
The humidity sensor includes two thermistors as shown
inthe illustration.One thermistorishoused intheclosed
vesselfilledwith dryair whileanother inthe openvessel.
Eachsensorisprovidedwiththeprotectivecovermadeof
metal mesh to be protected from the external airflow.
(2)Operational Principle of Humidity Sensor
The figure below shows the basic structure of an
absolute 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
operational amplifier.
Eachthermistorissuppliedwithacurrenttokeepitheated
at about 150οC (302οF), the resultant heat is dissipated
intheairandifthetwothermistorsareplacedindifferent
humidity conditions they show different degrees of heat
conductivity leading to a potential difference between
themcausinganoutputvoltagefromthebridgecircuit,the
intensity of which is increased as the absolute humidity
of the air increases. Since the output is varied every
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 absolute humidity circuit to allow the LSI to
control sensor cooking of the unit. When the unit is set
in the sensor cooking mode, 16 seconds clearing cycle
occurs than the detector circuit starts to function and
the LSI observes the initial voltage available at its AN6
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 R45 ~ R49.Changing
HUMIDITY SENSOR CIRCUIT
the resistance values results in that there is the same
potential at both F-3 terminal of the absolute humidity
sensor and AN6 terminal of the LSI.The voltage of AN7
terminalwillindicateabout+2.5V.Thisinitialbalancingis
setupabout16secondsaftertheunitisputintheSensor
Cookingmode.Asthesensorcookingproceeds,thefood
is heated to generate moisture by which the resistance
balance of the bridge circuit is deviated to increase the
voltage available at AN6 terminal of the LSI.
Then the LSI observes that voltage at AN7 terminal and
comparesitwithitsinitialvalue,andwhenthecomparison
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 AN7
terminal 16 seconds after the unit has been put in the
Sensor Cooking mode, if it is not possible to balance
the bridge circuit due to disconnection of the absolute
humidity sensor, ERROR will appear on the display and
the cooking is stopped.
ventilation opening for sensing
Sensing part
(Open vessel) Sensing part (Closed vessel)
Thermistors
S
C
R3
R1
R2
+
Operational
amplifier Output
voltage
S : Thermistor
open vessel
C : Thermistor
closed vessel
2
Absolute humidity (g/m )
Output voltage
Absolute humidity vs,
output voltage characteristic
R43 1.8K
VA : +15V VC : +5V
R42 3.57K
R41 3.32K
S
C
R51 47K
R45 620K
R46 300K
R47 150K
R48 75K
R49 37.4K
R44 360K
R50 10K
3
F2
8
4
1
2IC5
+
-
R40 430
C42 0.1µF
D40 D41
R52 47K
86
39
P74
P73
P72
P01
P71
P70
AN6 SW1
SW2
SW3
SW4
SW5
AN5
LSI
(IC1)
38
36
51
35
34
33
32
C. Thermistor in
closed vessel
S. Thermistor in
open vessel
F3
F1

20
KB-6524PS
KB-6524PK
KB-6524PW
PRECAUTIONS FOR USING LEAD-FREE SOLDER
1. 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:
Indicates lead-free solder of tin, silver and copper.
2. 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 40oC higher than tin/lead alloy solder, it is recommend that
a dedicated bit is used, and that the iron temperature is adjusted accordingly.
3. Soldering
As the melting point of lead-free solder (Sn-Ag-Cu) is higher and has poorer wett 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