Daewoo KOC-870T0S User manual

Service Manual
Microwave Oven
Model: KOC-870T0S
KOC-875T0S
DAEWOO ELECTRON CS CO., LTD.
S/M No. : C870T0S003
✔ 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 magnetron or other micro-
wave 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 com-
partments, 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.
TABLE OF CONTENTS
PROPER USE AND SERVICE PRECAUTIONS 2
SPECIFICATIONS 3
NAMES AND FUNCTION OF PARTS 4
CONTROL PANEL 5
OPERATION 6
INTERLOCK MECHANISM FUNCTIONS AND ADJUSTMENTS 7
PRECAUTIONS FOR DISASSEMBLY AND REPAIR 9
DISASSEMBLY AND ASSEMBLY 10
TROUBLE SHOOTING GUIDE 18
MEASUREMENT 24
COMPONENT TEST PROCEDURE 26
WIRING DIAGRAM 27
SCHEMATIC DIAGRAM 28
EXPLODED VIEWS AND PARTS LIST 31
PRINTED WIRING BOARD 32
P.C.B. CIRCUIT DIAGRAM 39
P.C.B. LOCATION NO. 40

2
PROPER USE AND SERVICE PRECAUTIONS
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) This microwave oven weight 17.6kg (38.9 lbs.) and must be placed on a horizontal base strong enough to support
this weight.
2) The oven should be placed as far from high temperature source and vapour as possible.
3) The power supply cord is about 1.1m (3.6ft) long. Earthing is required when connecting the power source.
4) Maximum power consumption of this oven is approximately 2.6Kw(230V). It is suggested that the unit is operated on
such power line (about 13 amperes) that can provide more power than this rating.
5) Object must not be placed on the top enclosure so as not to obstruct air flow for ventilation.
The wires 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 the the terminal in the plug which is marked with
the letter ‘E’ or by earth symbol or 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.
WARNING : This appliance must be earthed.
NOTE : This oven is designed for counter-top use only.
IMPORTANT

3
MODEL KOC-870T0S KOC-870T5S
POWER SUPPLY 230V ~ , 50Hz 240V~, 50Hz 230V~, 50Hz
MICROWAVE POWER CONSUMPTION 1,550 W 1,550 W 1,550 W
OUTPUT POWER 900 W (IEC 705) 900W(IEC 706) 900 W (IEC 705)
FREQUENCY 2,450 MHZ 2,450MHz 2,450MHz
GRILL POWER CONSUMPTION 1,150 W 1,200 W 1,150 W
CONVECTION POWER CONSUMPTION 1,550 W 1,600 W 1,550 W
AUTO COOK POWER CONSUMPTION 2,600 W 2,650 W 1,950 W
OUTSIDE DIMENSIONS (W X D X H ) 501 X 398 X 320 mm (19.7 X 15.7 X 12.6 in.)
CAVITY DIMENSIONS (W X D X H) 310 X 310 X 229 mm (12.2 X 12.6 X 9.0 in.)
NET WEIGHT 17.6 kg (38.9 Ibs.)
TIMER 60 minutes
SELECT FUNCTION Microwave/Grill /Convection /Combination
MICROWAVE POWER LEVEL 10 stages
* Specifications subject to change without notice.
332
294 320
501
210
402
Grill
M/W
Combi +1 min
Pie Temp +10 sec
GRILL COMBI WEIGHT
DEFROST
TIME
AUTO
COOK PIE TEMP COOK
kg
1. Roast Beef
2. Roast Pork
3. Roast Chicken
4. Fish Fillets
5. Vegetable
Auto Cook
TIME/WEIGHT
Speedy
-
+
Clock
Defrost
M/W
STOP/
CLEAR START
Fig. 1 Front View Fig. 2 Side View
SPECIFICATIONS
EXTERNAL VIEWS

4
3 5 64
2
1 9 8
8
10
7
11
Grill
M/W
Combi +1 min
Pie Temp +10 sec
GRILL COMBI WEIGHT
DEFROST
TIME
AUTO
COOK PIE TEMP COOK
kg
1. Roast Beef
2. Roast Pork
3. Roast Chicken
4. Fish Fillets
5. Vegetable
Auto Cook
TIME/WEIGHT
Speedy
-
+
Clock
Defrost
M/W
STOP/
CLEAR START
1 DOOR SEAL- Door seal maintains the microwave
within the oven cavity and prevents microwave leakage.
2 DOOR HOOK - When door is closed, it will automatically
lock shut. If door is opened while oven is operating,
magnetron tube will immediately stop operating.
3 DOOR SCREEN - Allows viewing of food. Microwave
cannot pass through perforations in screen.
4 GRILL HEATER- Turns on when grill and simulta-
neous cooking is selected.
5 OVEN LAMP- Automatically turns on during oven
operating.
6 SAFETY INTERLOCK SYSTEM
7 CONTROL PANEL
8 TURNTABLE TRAY - Rotates during cooking and
ensure even distribution of Microwaves. It can also be
used as a cooking utensil.
9 OVEN FRONT PLATE
0 ROTATING BASE- This fits over the shaft in the center
of the oven’s cavity floor. This is to remain in the oven for
all cooking. It should only be removed for cleaning.
q UNDER HEATER
NAMES AND FUNCTION OF PARTS

5
CONTROL PANEL
When blinking, the oven is
operating in COMBI cooking. When blinking, the oven is
operating in WEIGHT
DEFROST.
When blinking, the oven is
operating in TIME DEFROST.
When blinking, the oven is
operating in weight input
mode.
Cooking time is increased
by 1 minute.
Cooking time is increased
by 10 seconds.
FUNCTION BUTTON
Used to select desired oven
operation.;Grill, Combi, Pie
Temp, Auto Cook, M/W,
Defrost.
Stop/Clear Button-Used to select
desired oven operation.;Grill, Combi,
Pie Temp, Auto Cook, M/W,Defrost.
Start Button-Used to start the
selectee cycle.
Speedy Cook Button-
Used to set desired time.
(Time increases by 30 seconds
from 30 seconds to 5 minutes.)
Guide Lamp-
When blinking, it informs you to
be ready to operate dial knob.
Dial Knob-
Used to set the cooking time,
time of day and weight input.
When blinking, the oven is
operating in GRILL
When blinking, the onve is
operating in MICROWAVE
COOK
When blinking, the oven is
operating in AUTO COOK.
When blinking, the oven is
operating in PIE COOK.
Microwave Button-Used to
select the variable microwave
power level. If this button is
pressed for more than 1.3
seconds, number is scrolled
up automatically.
Temp Button Used to set
desired temperature. If this
button pressed for more than
1.3 seconds, number is scrolled
up automatically.
Clock Button-Used to set
time.
When blinking, the oven is
operating in CONVECTION
(TEMP COOK)
Grill
M/W
Combi +1 min
Pie Temp +10 sec
GRILL COMBI WEIGHT
DEFROST
TIME
AUTO
COOK PIE TEMP COOK Kg
1. Roast Beef
2. Roast Pork
3. Roast Chicken
4. Fish Fillets
5. Vegetable
Auto Cook
TIME/WEIGHT
Speedy
-
+
Clock
Defrost
M/W
STOP/
CLEAR START

6
TO STOP THE OVEN WHILE THE OVEN IS OPERATING
1. Press (STOP / CLEAR) button.
- The (STOP) indicator starts blinking.
- You can restart the oven by touching (START) button.
- Touch once more to erase all instruction except clock.
2. Open the door
- You can restart the oven by closing the door and touching button.
ERASING INSTRUCTIONS
•Touch (STOP/CLEAR) button to erase all instructions you set previously.
•Opening the oven door during cooking dose not erase cooking instruction.
•If you touch button during operation, the cooking instructions is all erased.
OPERATION
NOTE : Oven stops operating when door open.

7
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.
(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 lever downward.
The lever press the button of the primary interlock switch to bring it under ‘ON’condition.
INTERLOCK MECHANISM FUNCTIONS AND ADJUSTMENTS
Mounting
screw
Upper Hook
Primary
interlock
switch

8
(2) Monitor interlock switch
When the door is closed, the hook pushes the lever forward, and pushes the Latch Lever downward the lever press the
button of the interlock monitor switch to bring it under ‘OFF’condition. The latch Lever press the button on the secondary
interlock switch to bring it under ‘ON’condition.
- Adjustment
Interlock monitor switch
When the door is closed, the monitor switch should be opened before other switches close.
When the door is opened, the monitor switch should be closed after other switches open.
Adjustment steps :
a) Loosen the two mounting screws.
b) Adjust the interlock switch assembly position.
c) Make sure that the latch lever moves smoothly after adjustment is completed.
d) Completely tighten the two mounting screws.

9
PRECAUTIONS FOR DISASSEMBLY AND REPAIR
- Cautions to be observed when trouble shooting.
Unlike many other appliances, the microwave oven is high-voltage, high-current equipment. It is completely safe 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 war rubber gloves when servicing the high voltage side.
(3)Warning about the electric charge in the high voltage capacitor. When inspecting and repairing the high voltage side,
always short the capacitor terminals and make sure of discharge.
1. Check the earthing.
Do not operate on a 2-wire extension cord.
The microwave oven is designed to be used when earthed.
It is imperative, therefore, to makes 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 stops, 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 screw driver to discharge.
(4)When the 15Amp fuse(870T5S: 12Amp) is blown out due to the operation of the monitor switch; replace secondary
interlock switch and monitor switch. Refer to 17 page for the necessary adjustment.
(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 repairing 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 - H.V. Transformer, magnetron,
H.V. Diode, H.V. Capacitor.