Daewoo KOC-9Q4T User manual

Service Manual
Microwave Oven
Model: KOC-9Q4T
S/M No. :
Mar. 2010
✔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).

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MODEL KOC-9Q3T7S
POWER SUPPLY 230V~50Hz, SINGLE PHASE WITH EARTHING
MICROWAVE 1400W
POWER GRILL 1250W
CONSUMPTION CONVECTION 1250W
COMBINATION 2700W
MICROWAVE ENERGY OUTPUT 900W (IEC 705)
MICROWAVE FREQUENCY 2450MHz
OUTSIDE DIMENSIONS (W X D X H) 513X382X311mm(20.2X15X12.2 in.)
CAVITY DIMENSIONS (W X D X H) 354X341X231mm(13.9X13.4X9.1 in.)
NET WEIGHT Approx. 16.6Kg (46.6 lbs.)
TIMER 60 minutes
FUNCTION SELECTIONS Microwave / Grill / Convection / Combination
POWER SELECTIONS 10 LEVELS
CAVITY VOLUME 0.99 Cu. Ft
* SPECIFICATION ARE SUBJECT TO CHANGE WITHOUT NOTICE.
MODEL KOC-9Q4T
POWER SUPPLY 230V~50Hz, SINGLE PHASE WITH EARTHING
MICROWAVE 1400W
POWER GRILL 1250W
CONSUMPTION CONVECTION 1250W
COMBINATION 2700W
MICROWAVE ENERGY OUTPUT 900W (IEC 705)
MICROWAVE FREQUENCY 2450MHz
OUTSIDE DIMENSIONS (W X D X H) 513X383X311mm(20.2X15.1X12.2 in.)
CAVITY DIMENSIONS (W X D X H) 354X341X231mm(13.9X13.4X9.1 in.)
NET WEIGHT Approx. 16.6Kg (46.6 lbs.)
TIMER 60 minutes
FUNCTION SELECTIONS Microwave / Grill / Convection / Combination
POWER SELECTIONS 10 LEVELS
CAVITY VOLUME 0.99 Cu. Ft
* SPECIFICATION ARE SUBJECT TO CHANGE WITHOUT NOTICE.
2. SPECIFICATIONS

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3. EXTERNAL VIEW
382513
311
1. OUTER DIMENSION
1) KOC-9Q3T7S
383513
311
2) KOC-9Q4T

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1
23 45678
9
101112
13
11. DOOR HOOK
Hook automatically locks and holds the door when the door shuts. If the door opens while the oven is operating,
the oven will stop operating immediately.
12. DOOR SEAL
Door seal prevents the microwave leakage from the oven cavity.
13. DOOR VIEWING SCREEN
Food, inside of oven, can be observed through the door viewing screen. It is designed that the microwave cannot
pass through the screen.
14. TOP HEATER
Top heater turns on if any of heater related mode operates.
15. OVEN FRONT PLATE
16. CONVECTION INLET
17. OVEN LAMP
Oven lamp turns on anytime the door opens and oven operates.
18. SAFETY INTERLOCK SYSTEM
19. CONTROL PANEL
10. METAL RACK
11. COUPLER
Coupler located at the center of the oven cavity and it couples between the motor and the glass tray.
12. ROLLER GUIDE
Roller guide must be used anytime with the glass tray.
13. GLASS TRAY
Glass tray is made of special heat resistant glass material. It must be always properly fitted with the coupler and
the roller guide.
2. FEATURE DIAGRAM

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11Display : Cooking time, power level, program
indicators and present time are displayed.
MW ( ): When blinking, the oven is
operating in MICROWAVE COOK mode.
Grill ( ): When blinking, the oven is
operating in GRILL mode.
Combi ( ): When blinking, the oven is
operating in COMBI mode.
Convection ( ): When blinking, the oven is
operating in CONVECTION mode.
Defrost ( ): When blinking, the oven is
operating in DEFROST mode.
Auto-cook ( ): When blinking, the oven is
operating in AUTO COOK mode.
Warm ( ): When blinking, the oven is
operating in WARM mode.
Steam Cleaning ( ): When blinking, the
oven is operating in STEAM CLEANING
mode.
gram ( ): When blinking, the oven is
operating in weight input mode.
22Auto cook : Used to cook or reheat.
33Defrost : Used to defrost foods.
44MW : Used to set power level of the
microwave.
55Grill : Used to select grill mode.
66Combi : Used to select combi mode.
77Convection : Used to select convection
mode and selected temp.
88Clock : Used to set clock.
99STEAM CLEANING : Used to clean the
inside of the oven.
00Warm or Dish Warm : Used to keep the food
or dish warm.
qqDial knob : Used to set time, weight and
quantity.
wwSTART/SPEEDY COOK : Used to start a
program or a speedy start(each press adds
30 seconds of microwave cooking time).
eeSTOP/CLEAR : Used to stop the oven
operation or to delete the cooking data.
1
2
e
3
w
q
4
5
6
7
8
9
0
2) KOC-9Q4T

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8. TROUBLESHOOTING GUIDE
Following the procedure below to check if the oven is defective or not.
1) Check grounding 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 connection of the terminals and power cord before check the parts listed below.
CONDITION CHECK
Check continuity of
interlock monitor switch with
door closed
(COM↔NC)
Check continuity of
both primary and secondary
interlock switch with door closed
Malfunction of
Interlock
monitor switch
Malfunction of
interlock switch
RESULT
Continuity
No continuity
CAUSE REMEDY
Replace
(COM↔NC)
Fuse blows.
Replace
Shorted contacts
of primary
interlock Switch
Continuity Replace
Check continuity of
primary interlock switch contact with
door partially open until interlock
monitor switch contact close
( COM↔NC close )
Defective low
voltage
transformer
Defective
high voltage
transformer
0 Ωor infinite Replace
Replace
Check continuity of
primary winding of low voltage
transformer
Disconnect high voltage
fuse and operate the unit
No
Continuity
Continuity
Approx.
530Ω~ 1130Ω
( normal )
Fuse again
blows

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CONDITION CHECK
Check continuity of
magnetron Defective
magnetron.
RESULT
No
continuity
CAUSE REMEDY
Replace
Outlet has
proper
voltage
fuse does not
blow? Check continuity of noise filter
board Defective line
filter board
No
continuity Replace
Check continuity of
power supply cord
Defective touch
control circuit Replace
Open power
supply cord
No
continuity
No
continuity
Replace
NOTE : All these switches must be replaced at the same time, please refer to (7.Interlock mechanism and
adjust) for adjustment instructions
(TROUBLE 2)
Display shows all figures selected, but oven does not start cooking, even though desired program and time
are set and start button is tapped.
CONDITION CHECK
Check continuity of
primary interlock switch Malfunction of
primary interlock
switch
RESULT
No
continuity
CAUSE REMEDY
Adjust or
replace
Turn table
motor and
oven lamp
do
not turn on
Check D.C voltage
being supplied to
RELAY(RY2) coil
Fault contacts
of RELAY
(RY2) or open
relay coil.
Replace
Check continuity of
secondary interlock
and D.O.M switch
Malfunction of
secondary
Interlock and
D.O.M switch
No
continuity Adjust or
replace
Defective touch
control Circuit
0V
Approx.
12V DC
Replace

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TROUBLE 3) No microwave oscillation even though fan motor rotates.
CONDITION CHECK RESULT
Check continuity of
high voltage capacitor terminals
with wires removed
Continuity
CAUSE
Defective
high voltage
transformer
Defective
high voltage
fuse
REMEDY
1
Replace
No
microwave
oscillation
Check continuity of
high voltage rectifier in forward
and backward
direction with DC megger
Continuity
in backward
direction
Defective high
voltage rectifier Replace
Connect megger leads to
magnetron terminal and
magnetron body
Continuity Defective
magnetron
2
1 Check resistance of primary
and secondary coil of high
voltage transformer
0 or Defective
high voltage
transformer
Replace
Check continuity of
high voltage fuse
No microwave oscillation
No
continuity
2 Check continuity of
magnetron heater with wires
removed
No continuity Defective
magnetron Replace
1 Check continuity of filament
terminal of high voltage
transformer
No continuity Defective high
voltage
transformer
Replace
Check D.C voltage
being supplied to
RELAY (RY1) coil
0 V Defective
touch control
circuit
Replace
Approx.
12V DC Faulty contacts of
RELAY
(RY1) or open
relay coil
Replace

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(TROUBLE 4)
Grill heater (upper heater) is not heated; food will not become hot.
CONDITION CHECK
Check continuity of
primary interlock switch Malfunction of
primary Interlock
switch
RESULT
No
continuity
CAUSE REMEDY
CAUSE REMEDY
Adjust or
replace
Main heater
is not heated.
Check D.C voltage
being supplied to
RELAY (RY3) coil
Faulty contacts of
RELAY
(RY3) or open
relay coil
Replace
Check continuity of
DOM switch Malfunction of DOM switch
No
continuity Adjust or
replace
Defective touch
control circuit
0V
Approx.
12V DC
Replace
Check continuity of
heater Defective heater
No
continuity Replace
(TROUBLE 5)
1) Convection heater is not heated; food will not become hot.
2) Convection fan motor does no rotate.
CONDITION CHECK
Check continuity of
primary interlock switch Malfunction of
primary Interlock
switch
RESULT
No
continuity Adjust or
replace
1)Sub heater
is not
heated.
2)Convection
fan and
motor does
not rotate.
Check D.C voltage
being supplied to
RELAY (RY4, RY2) coil
Faulty contacts of
RELAY
(RY4, RY2) or
open relay coil
Replace
Check continuity of
DOM switch Malfunction of DOM switch
No
continuity Adjust or
replace
Defective touch
control circuit
0V
Approx.
12V DC
Replace
Check continuity of
(heater or motor) Defective heater
or motor
No
continuity Replace

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CONDITION CHECK
Check each button for
continuity of the button Malfunction of
touch control
circuit of control
box sub-assembly
RESULT
Normal
CAUSE REMEDY
Replace
control box
sub-assembly
Display does
not show
programming
at all, even if
keyboard is
touched.
(TROUBLE 6)
The following visual conditions indicate a probable defective touch control Circuit or button P.C.B. assembly
1. Incomplete segments.
1) segment missing
2) partial segments missing
3) digit flickering other than normal fluorescent slight flickering
2. A distinct change in the brightness of one or more numbers exists in the
display.
3. One or more digits in the display are not on when they should be.
4. Display does not count down or up with time cooking or clock operation.
5. Oven is programmable and cooks normally but no display shows.
6. Display obviously jumps in time while counting down.
7. Display counts down noticeably too fast while cooking.
8. Display does not show the time of day when clear button is touched.
9. Oven lamp and turn table motor do not stop although cooking is finished.
Check if the RELAY(RY2) contacts close and if they are close, replace touch control circuit.
CAUSE REMEDY
(TROUBLE 7)
When “ERROR 2 ERROR 3” come on display.
CONDITION CHECK
Check continuity of thermistor
(resistance of thermistor) Replace
RESULT
0Ωor infinite Replace
“ERROR 2 &
ERROR 3”
come on
display
Check continuity of heater
(main, sub)
Defective touch
control circuit Replace
Approx
200k~300kΩ
(room
temperature)
Defective
heater
No
continuity
continuity
Replace