Daewoo KOR-63XQ0S User manual

Service Manual
Microwave Oven
Model : KOR-63XQ0S
DAEWOO ELECTRONICS CO., LTD.
http://svc.dwe.co.kr
S/M No.: R63XQ0S001
✔ Caution
: In this Manual, some parts can be changed for improving, their
performance without notice in the parts list. So, if you need the
latest parts information,please refer to PPL(Parts Price List) in
Service Information Center (http://svc.dwe.co.kr).

1
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 magentron 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 power to the microwave oven 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.
SAFETY AND PRECAUTIONS
1. FOR SAFE OPERATION
2. FOR SAFE SERVICE PROCEDURES
SPECIFICATIONS
EXTERNAL VIEW
1. OUTER DIMENSION
2. FEATURE DIAGRAM
3. CONTROL PANEL
INSTALLATION
OPERATIONS AND FUNCTIONS
DISASSEMBLY AND ASSEMBLY
INTERLOCK MECHANISM AND ADJUSTMENT
TROUBLE SHOOTING GUIDE
MEASUREMENT AND TEST
1. MEASUREMENT OF THE MICROWAVE POWER OUTPUT
2. MICROWAVE RADIATION TEST
3. COMPONENT TEST PROCEDURE
WIRING DIAGRAM
PRINTED CIRCUIT BOARD
1. CIRUCIT CHECK PROCECDURE
2. PCB CIRCUIT DIAGRAM
3. P.C.B. LOCATION NO
EXPLODED VIEW AND PARTS LIST
1. DOOR ASSEMBLY
2. CONTROL PANEL ASSEMBLY
3. TOTAL ASSEMBLY
2
2
2
3
4
4
5
6
8
9
10
17
18
22
22
23
24
25
26
26
29
30
32
32
32
32
TABLE OF CONTENTS
TABLE OF CONTENTS

2
1. FOR SAFE OPERATION
Damage that allows the microwave energy (that cooks or heats the food) to escape will result in poor cooking and may cause
serious bodily injury to the operator.
IF ANY OF THE FOLLOWING CONDITIONS EXIST, OPERATOR MUST NOT USE THE APPLIANCE.
(only a trained service personnel should make repairs.)
(1) A broken door hinge.
(2) A broken door viewing screen.
(3) A broken front panel, oven cavity.
(4) A loosened door lock.
(5) A broken door lock.
The door gasket plate and oven cavity surface should be kept clean.
No grease, soil or spatter should be allowed to build up on these surfaces or inside the oven.
DO NOT ATTEMPT TO OPERATE THIS APPLIANCE WITH THE DOOR OPEN.
The microwave oven has concealed switches to make sure the power is turned off when the door is opened.
Do not attempt to defeat them.
DO NOT ATTEMPT TO SERVICE THIS APPLIANCE UNTIL YOU HAVE READ THIS SERVICE MANUAL.
2. FOR SAFE SERVICE PROCEDURES.
1. If the oven is operative prior to servicing, a microwave emission check should be performed prior to servicing the oven.
2. If any certified oven unit is found to servicing, a microwave emission check should be performed prior to servicing the oven.
(1) inform the manufacturer, importer or assembler,
(2) repair the unit at no cost to the owner,
(3) attempt to ascertain the cause of the excessive leakage,
(4) tell the owner of the unit not to use the unit until the oven has been brought into compliance.
3. If the oven operates with the door open, the service person should tell the user not to operate the oven and contact the
manufacturer immediately.
IMPORTANT
The wire in this mains lead coloured in accordance with the following code.
Green-and-yellow :Earth
Blue :Neutral
Brown :Live
As the colours of the wires in the mains lead of this appliance may not correspond with the coloured markings identifying the
terminals in your plug, proceed as follows:
The wire which is coloured green-and-yellow must be connected to the terminal in the plug which is marked with the letter
‘E’, earth symbol or coloured green-and-yellow.
The wire which is coloured blue must be connected to the terminal which is marked with the letter ‘N’ or coloured black.
The wire which is coloured brown must be connected to the terminal which is marked with the letter ‘L’ or coloured red.
NOTE : This oven is designed for counter-top use only.
SAFETY AND PRECAUTIONS

MODEL
POWER SUPPLY
MICROWAVE
GRILL
COMBINATION
MICROWAVE ENERGY OUTPUT
MICROWAVE FREQUENCY
OUTSIDE DIMENSIONS (W×H×D)
CAVITY DIMENSIONS (W×H×D)
NET WEIGHT
TIMER
FUNCTION SELECTIONS
POWER SELECTIONS
CAVITY VOLUME
3
♣SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE.
KOR-63XQ
230V~50Hz SINGLE PHASE WITH EARTHING
1200W
800W
2450MHz
465×279×352 mm (18.3×11.0×13.9 in.)
290×220×290 mm (11.4×8.7×11.4 in.)
APPROX. 13Kg(28.7 lbs.)
59 min. 99 sec
MICROWAVE
10 LEVELS
0.7 Cu. Ft
POWER
CONSUMPTION
SPECIFICATIONS

4
1. OUTER DIMENSION
EXTERNAL VIEW
WEIGHT TIME START
DEFROSTSTAGE AUTO
LOCK NO CUP g
Auto Cook
1. Raked Potato
2, Fresh Vegetable
3. Soup
4. Fish Fillets
5. Meat Loaf
Menu
Weight
Auto Def.
Beverage
popcorn
Muffin
Frozen
Pizza
Dinner
Plate
PowerClock / A.Start
Speedy Cook
Feeding
Bottle
123
456
789
0
Stop/Clear Start
1 2

5
2. FEATURE DIAGRAM
1. DOOR latch
When the door is closed it will automatically shut off.
If the door is opened while the oven is operating. The
magnetron will automatically shut off.
2. DOOR seal
The door seal maintains the microwave within the oven
cavity and prevents microwave leakage.
3. Oven cavity.
4. Spatter shield
Protects the microwave outlet from splashes of cooking
foods.
5. Safety interlock system
Prevents the oven from operating while the door is
opened.
6. Door release button
Pushing this button stops oven operation and opens the
door.
7. Glass cooking tray
Made of special heat resistant glass. The tray must always
be in proper position before operating. Do not cook food
directly on the tray.
8. Roller guide
Supports the glass cooking tray.
9. Door screen
Allows viewing of food. The screen is designed so that
light can pass through, but not the microwaves.
10. Time set pad
Used to set the cooking time and the present time.
11. Display
Cooking time, power level, present time are displayed.
12. Speedy cook - Touch to set the any desired reheat
setting.
13. Popcorn - Used to cook popcorn.
14. Muffin - Used to cook muffin.
15. Baked potato - Used to baked potato.
16. Dinner plate - Used to reheat dinner plate.
17. Soup - Used to reheat soup.
18. Beverage - Used to reheat beverage.
19. Frozen pizza - Used to reheat frozen pizza.
20. Fresh vegetable - Used to blanch fresh vegetable.
21. More - Used to add on one touch cooking
22. Less - Used to remove one touch cooking.
23. Auto defrost - Used to defrost foods.
24. Power - Used to set power level.
25. Clock/A. start - Used to set clock & Used to set auto
start.
26. Feeding bottle - Used to sterilize bottle.
27. Stop/Clear - Used to stop the oven operation or to delete
the cooking data.
28. Start - Used to start a selected operation.

6
1. Steady, flat location
This microwave oven should be set on a steady, flat surface
This microwave oven is designed for counter top use only.
2. Leave space behind and side
All air vents should be kept a clearance. If all vents are covered during operation, the oven may overheat and, eventually,
cause failure.
3. Away from Radio and TV sets
Poor television reception and radio interference may result if the oven is located close to a TV, Radio, antenna or feeder and so on.
Position the oven as far from them as possible.
4. Away from heating appliances and water taps
Keep the oven away from hot air, steam or splash when choosing a place to position it, or the insulation might be adversely
affected and breakdowns occur.
5. Power supply
󳢯Check your local power source. This microwave oven requires a current of approximately 6 amperes, 230V, 50Hz
󳢯Power supply cord is about 0.8 meters long.
󳢯The voltage used must be the same as specified on this oven. Using a higher voltage may result in a fire or other accident
causing oven damage. Using low voltage will cause slow cooking. We are not responsible for damage resulting from use of
this oven with a voltage of ampere fuse other than those specified.
󳢯This appliance is supplied with cable of special type, which, if damaged, must be repaired with cable of same type.
󳢯Such a cable can be purchased from DAEWOO and must be installed by a Qualified Person.
6. Examine the oven after unpacking for any damage such as:
A misaligned door, broken door or a dent in cavity.
If any of the above are visible, DO NOT INSTALL, and notify dealer immediately.
7. Do not operate the oven if it is colder than room temperature.
(This may occur during delivery in cold weather.) Allow the oven to become room temperature before operating.
This appliance must be earthed. In the event of an electrical short circuit, earthing reduces the risk of the electric shock by
providing an escape wire for the electric current. This appliance is equipped with a cord having a earthing wire with a earthing
plug. The plug must be plugged into an outlet that is propely installed and earthed.
WARNING
Improper use of the earthing plug can result in a risk of electric shock.
Consult a qualified electrician or serviceman if the earthing instructions are not completely understood, or if doubt exists as
to whether the appliance is properly earthed, and either.
If it is necessary to use an extension cord, use only a 3-wire extension cord that has a 3-blade earthing plug, and a 3-slot
receptacle that will accept the plug on the appliance.
The marked rating of the extension cord should be equal to or greater than the electrical rating of the appliance, or Do not
use an extension cord.
INSTALLATION
EARTHING INSTRUCTIONS

7
Wattage output chart
The power level is set by pressing the Power pad. The chart shows the display, the power level and the percentage of power.
1. Connect the main lead to an electrical outlet.
2. After placing the food in a suitable container, open the oven door and put it on the glass tray. The glass tray must always be in
place during cooking.
3. Close the door securely.
4. When the oven door is opened, the light turns off.
5. The oven door can be opened at any time during operation by touching the door release button on the control panel.
The oven will automatically shut off. To restart the oven, close the door and then touch START.
6. Each time a pad is touched, a BEEP will sound to acknowledge the touch.
7. The oven automatically cook on full power unless set to a lower power level.
8. The display will show : 0 when the oven is plugged in.
9. Time clock returns to the present time when the cooking time ends.
10. When the STOP/CLEAR pad is touched during the oven operation, the oven stops cooking and all information retained.
To erase all information(except the present time), touch the STOP/CLEAR pad once more. If the oven door is opened during
the oven operation, all informaiton is retained.
11. If the START pad is touched and the oven does not operate, check the area between the door and door is closed securely.
The oven will not start cooking under the door is completely closed or the program has been reset.
OPERATIONS AND FUNCTIONS
Make sure the ven is pr perly installed and plugged int the electrical utlet.
POWER
9
8
7
6
5
4
3
2
1
0
P-HI
P-90
P-80
P-70
P-60
P-50
P-40
P-30
P-20
P-10
P-00
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Power Level (Display) Approximate Percentage of Power
Touch Power pad,
Once the touch

8
Cautions to be observed when trouble shooting.
Unlike many other appliances, the microwave oven is high-voltage, high-current equipment. It is completely safety during normal
operation. However, carelessness in servicing the oven can result in an electric shock or possible danger from a short circuit. You
are asked to observe the following precautions carefully.
1. Always remove the power plug from the outlet before servicing.
2. Use an insulated screwdriver and ware rubber gloves when servicing the high voltage side.
3. Discharge the high voltage capacitor before touching any oven components or wiring.
(1) Check the earthed.
Do not operate on a two-wire extension cord.
The microwave oven is designed to be used with earthed.
It is imperative, therefore, to make sure it is earthed properly
before beginning repair work.
(2) Warning about the electric charge in the high voltage capacitor.
For about 30 seconds after the operation has stopped and electric
charge remains in the high voltage capacitor. When replacing
or checking parts, short between oven chassis and the negative
high terminal of the high voltage capacitor, by using a properly
insulated screwdriver to discharge.
4. When the 12A fuse is blown out due to the operation of the monitor
switch, replace primary interlock switch, secondary interlock switch
and interlock monitor switch.
5. After repair or replacement of parts, make sure that the screws are
properly tightened, and all electrical connections are tightened.
6. Do not operate without cabinet.
CAUTION : Service personnel should remove their watches whenever working close to or replacing the magnetron.
WARNING : When servicing the appliance, need a care of touching or replacing high potential parts because of electrical
shock or exposing microwave. These parts are as follows - HV Transformer, Magnetron, HV Capacitor, HV
Diode. HV Fuse.
DISASSEMBLY AND ASSEMBLY

9
1. To remove cabinet
1) Remove three screws on cabinet back.
2) Push the cabinet backward.
2. To remove door assembly
1) Remove a screws which secure the stopper hinge top.
2) Remove the door assembly from top plate of cavity.
3) Reverse the above for reassembly.
NOTE : After replacing the door assembly, perform a check of correct
alignment with the hinge and cavity front plate.

10
REF.NO
A01
A02
A03
A04
A05
A06
A07
A08
A09
PART CODE
3512202030
3517006180
3515304610
3515204100
3511705500
3517002800
3512300210
3513100700
3515101300
PART NAME
FRAME DOOR
BARRIER-SCREEN󳢣O
SUPPORTER BARR-S󳢣O
STOPPER HINGE󳢣T AS
DOOR WELD AS
BARRIER-SCREEN * I
GASKET DOOR
HOOK
SPRING HOOK
DESCRIPTION
ABS SG-175, SG-0760D
SAN
PP
KOR-63150S
KOR-61150S
POLYESTER TO. 1
PP
POM
PW1
Q’TY
1
1
1
1
1
1
1
1
1
REMARK
3. To remove door parts.
(1) KOR-63XQ0S
✔ Caution: In this Service Manual, some parts can be changed for improving, their performance without notice in the parts list. So, if you need the
latest parts information, please refer to PPL(Parts Price List) in Service information Center(http://svc.dwe.co.kr)

11
(1) Remove the gasket door from door plate.
(2) Remove the barrier screen inner from door plate.
(3) Remove the door frame from door plate.
(4) Remove the stopper hinge top from door plate.
(5) Remove the spring and the hook.
(6) Remove the supporter barrier screen outer from door frame.
(7) Remove the barrier screen outer from door frame.
(8) Reverse the above steps for reassembly.
4. Method to reduce the gap between the door seal and
the oven front surface.
(1) To reduce gap located on part ‘A’.
󳢯Loosen a screw on stopper hinge top, and then push the door
to contact the door seal to oven front surface.
󳢯Tighten a screw.
(1) To reduce gap located on part ‘B’.
󳢯Loosen two screws on stopper hinge under, and then push the
door to contact the door seal to oven front surface.
󳢯Tighten two screws.
A
B
NOTE : A small gap may be acceptable if the microwave leakage does not exceed 4mW/cm2.

12
REF.NO
B01
B02
B03
B04
B05
B06
B07
PART CODE
3518519700
3516710740
PKMPMSCY00
7122401211
3513701420
441G430171
3516904430
PART NAME
SWITCH MEMBRANE
CONTROL PANEL
PCB MAIN AS
SCREW TAPPING
LEVER DOOR OPEN
SPRING BUTTON
BUTTON DOOR OPEN
DESCRIPTION
KOR-618Q0S
ABS SG-175, SG-0760D
KOR-63XQ0S
T2S TRS 4󳢮12 MFZN
PP
SWP
ABS SG-175, SG-0760D
Q’TY
1
1
1
3
1
1
1
REMARK
5. To remove control panel parts.
(1) KOR-63XQ0S
✔ Caution: In this Service Manual, some parts can be changed for improving, their performance without notice in the parts list. So, if you need the
latest parts information, please refer to PPL(Parts Price List) in Service information Center(http://svc.dwe.co.kr)

13
6. To remove high voltage capacitor.
1) Remove a screw which secure the grounding ring terminal of the H.V.
diode and the capacitor holder.
2) Remove the H.V. diode from the capacitor holder.
3) Reverse the above steps for reassembly.
◆◆High voltage circuit wiring
7. To remove magnetron.
1) Remove a screw which secure the magnetron.
2) Remove the magnetron.
3) Reverse the above steps for reassembly.
NOTE : Never install the magnetron without the metallic gasket plate which is packed with each magnetron to prevent
microwave leakage. Whenever repair work is carried out on magnetron, check the microwave leakage. It shall not
exceed 4mW/cm2for a fully assembled oven with door normally closed.
(1) Remove the screw which secure the control panel, push up two snap fits and draw forward the control panel assembly.
(2) Remove the door open lever from the control panel.
(3) Remove four screws which secure the PCB assembly to control panel.
(4) Disconnect membrane tail from the connector of the PCB assembly.
(5) Detach membrane from the control panel.
(6) Remove door open button and button spring from the control panel.
(7) Reverse the above steps for reassembly.

9. To remove H.V.transformer.
1) Remove four screws holding the H.V.transformer.
2) Remove the H.V.transformer.
3) Reverse the above steps for reassembly.
8. To remove wind guide assembly.
1) Remove a screw for earthing.
2) Remove the noise filter from the wind guide.
3) Remove a screw which secure the wind guide assembly.
4) Draw forward the wind guide assembly.
5) Pull the fan from the motor shaft.
6) Remove two screws which secure the motor shaded pole.
7) Remove the motor shaded pole.
8) Reverse the above steps for reassembly.
14

15
(1) Primary interlock switch
When the door is closed, the hook locks the oven door. If the door is not closed properly. the oven will not operate.
When the door is closed, the hook pushes the button of the microswitch. Then the button of the primary interlock switch bring it
under ON condition.
(2) Secondary interlock switch and interlock monitor switch
When the door is closed, the hook pushes the lock lever downward. The lock lever presses the button of the interlock monitor
switch to bring it under NO condition and presses the button of the secondary interlock switch to bring it under ON condition.
(3) Adjustment steps
a) Loosen the one mounting screw.
b) Adjust interlock switch assembly position.
c) Make sure that lock lever moves smoothly after adjustment is completed.
d) Tighten completely one mounting screw.
The door lock mechanism is a device which has been specially designed to completely eliminate microwave radiation when the
door is opened during operation, and thus to perfectly prevent the danger resulting from the leakage of microwave.
INTERLOCK MECHANISM AND ADJUSTMENT
NOTE : Microwave emission test should be performed after adjusting interlock mechanism. If the microwave emission
exceed 4mW/cm2, readjust interlock mechanism.
ADJUSTMENT
Interlock monitor switch
When the door is closed, the interlock monitor switch should be changed(NO condition) before other switches are closed.
When the door is opened, the interlock monitor switch should be chanded(NC condition) after other switches are opened.

16
Following the procedure below to check if the oven is defective or not.
1) Check earthing before trouble checking.
2) Be careful of the high voltage circuit.
3) Discharge the high voltage capacitor.
4) When checking the continuity of the switches, fuse or high voltage transformer, disconnect one load wire from these parts and
check continuity with the AC plug removed. To do otherwise may result in a false reading or damage to your meter.
(TROUBLE 1)
Oven does not operate at all : any inputs can not be accepted.
NOTE : When electric parts are checked, be sure the power cord is not inserted the wall outlet.
Check wire harness, wiring and connected of the terminals and power cord before check the parts listed below.
CONDITION RESULT CAUSE REMEDY
Continuity
No continuity
Malfunction of
Interlock
monitor switch
Replace
NOTE 1
NOTE 1
NOTE 1
CHECK
Fuse blows. Check continuity of
interlock monitor switch with
door closed
(COM↔NC)
NO
Continuity
Continuity
Malfunction of
Interlock
switch
Replace
Check continuity of
both primary and secondary
interlock switch with door closed
Continuity Shorted contacts
of primary
interlock switch
Replace
Check continuity of
Primary interlock switch contact
with door partially open until
interlock monitor switch contact
close
(COM<->NO)
Check continuity of
Primary winding of low voltage
transformer
Fuse again
blows
Defective
high voltage
transformer
Replace
Disconnect high voltage
fuse and operate the unit
0Ωor infinite
Approx.
530~ 310
(normal)
Defective low
voltage
transformer
Replace
TROUBLE SHOOTING GUIDE

17
CONDITION RESULT CAUSE REMEDY
No
continuity
Defective
magnetron Replace
CHECK
Outlet has
proper voltage
Fuse does not
blow?
Check continuity of
magnetron
No
continuity
Defective line
filter board Replace
Check continuity of
noise filter board
No
continuity
Open power
supply cord Replace
Check continuity of
power supply cord
Normal Defective touch
control circuit Adjust
CONDITION RESULT CAUSE REMEDY
No
continuity
Malfunction of
primary interlock
switch
Adjust or
replace
CHECK
Turn table
motor and
oven lamp
do not turn on
Check continuity of
primary interlock switch
No
continuity
Malfunction of
secondary
interlock and
D.O.M. switch
Adjust or
replace
Check continuity of
secondary interlock
and D.O.M switches
0 V Defective touch
control circuit Replace
Approx.
15VDC
Fault contacts
of RELAY
(RY2) or open
relay coil
Replace
NOTE : All these switches must be replaced at the same time, please refer to “Interlock mechanism And Adjustment.”
(TROUBLE 2)
Display shows all figures selected, but oven does not start cooking, even though desired program and time are set and
start pad is tapped.
Check D.C. voltage
being supplied to
RELAY(RY2) coil

18
(TROUBLE 3)
No microwave oscillation even though fan motor rotates.
CONDITION RESULT CAUSE REMEDYCHECK
No
microwave
oscillation
No Continuity
Check continuity of
high voltage fuse
Replace high voltage fuse
Continuity Defective
high voltage
transformer
Replace
Check continuity of
high voltage capacitor
terminals with wires removed
Continuity in
backward
direction
Defective
high voltage
rectifier
Replace
Check continuity of high voltage
rectifier in forward and backward
direction with DC megger
Continuity Defective
magnetron
Replace
Connect megger leads to
magnetron terminal and
magnetron body
0Ω or ∞Defective high
voltage
transformer
Replace
Check resistance of primary and
secondary coil of high voltage
transformer
No continuity Defective
magnetron
Replace
Check continuity of
magnetron with wires
removed
No continuity Defective
high voltage
transformer
Replace
Check continuity of
filament terminal of high
voltage transformer
0 V Replace
Approx
15VDC
Faulty contacts
or RELAY
(RY1) or open
relay coil.
Replace
Check D.C. voltage
being supplied to
RELAY(RY1) coil
Defective
touch control
circuit

19
(TROUBLE 4)
The following visual conditions indicate a probable defective touch control circuit or membrane switch assembly
1. Incomplete segments,
1) Segment missing.
2) Partical segments missing.
3) Digit flickering other than normal display slight flickering.
4) “:0”does not display when power is on.
2. A distinct change in the display are not on when they numbers is the display.
3. One or more digits in the display are not on when they should be.
4. Display indicates a number different from one touched.
5. Specific numbers (for example 2 or 3) will not display when the panel is touched.
6. Display does not count down or up with time cooking or clock operation.
7. Oven is programmable and cooks normally but no display shows.
8. Display obviously jumps in time while counting down.
9. Display counts down noticeably too fast while cooking.
10. Display does not show the time of day when clear pad is touched.
11. Oven lamp and turntable motor do not stop although cooking is finished. Check if the RELAY 2 contacts close if they are close,
replace touch control circuit.
CONDITION RESULT CAUSE REMEDY
Normal Malfunction
of touch
control circuit
of control box
sub-assembly
Replace
control box
sub-assembly
CHECK
Display does
not show
programming
at all, even if
keyboard is
touched.
Abnormal Malfunction
of the membrane
keyboard
Replace the
membrane
keyboard
Check each pad or
continuity of the membrane
keyboard for the following
keyboard check procedure
NOTE : Before following the particular steps listed above in the trouble shooting guide for the membrane keyborad’s, failure,
please check for the continuity of each wire-harness between the membrane keyboard and P.C.B. assembly