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Service Manual
Microwave Oven
Model: KOR-1B4H0A

DAEWOO ELECTRONICS CO., LTD.

PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY
(a) Do not operate or allow the oven to be operated with the door open. (b) Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source, and make repairs if 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.

TABLE OF CONTENTS
SAFETY AND PRECAUTIONS........................................................................................................................................3 FOR SAFE OPERATION ...........................................................................................................................................3 FOR SAFE SERVICE PROCEDURES .....................................................................................................................3 SPECIFICATIONS ............................................................................................................................................................4 EXTERNAL VIEW .............................................................................................................................................................5 OUTER DIMENSION .................................................................................................................................................5 FEATURE DIAGRAM.................................................................................................................................................6 CONTROL PANEL .....................................................................................................................................................7 INSTALLATION ................................................................................................................................................................8 OPERATIONS AND FUNCTIONS ...................................................................................................................................9 DISASSEMBLY AND ASSMBLY...................................................................................................................................10 INTERLOCK MECHANISM AND ADJUSTMENT.........................................................................................................17 TROUBLE SHOOTING GUIDE ......................................................................................................................................18 MESUREMENT AND TEST............................................................................................................................................22 MEASUREMENT OF THE MICROWAVE POWER OUTPUT................................................................................22 MICROWAVE RADIATION TEST ...........................................................................................................................23 COMPONENT TEST PROCEDURE .......................................................................................................................24 WIRING DIAGRAM.........................................................................................................................................................25 PRINTED CIRCUIT BOARD...........................................................................................................................................26 CIRCUIT CHECK PROCEDURE.............................................................................................................................26 PCB CIRCUIT DIAGRAM ........................................................................................................................................29 P.C.B. LOCATION NO. ............................................................................................................................................30 EXPLODED VIEW AND PARTS LIST ...........................................................................................................................31 DOOR ASSEMBLY ..................................................................................................................................................31 CONTROL PANEL ASSEMBLY ..............................................................................................................................31 TOTAL ASSEMBLY .................................................................................................................................................31

2

SAFETY AND PRECAUTIONS
CAUTION : This Device is to be Serviced Only by Properly Qualified Service Personnel. Consult the Service Manual for Proper Service Procedures to Assure Continued Safety Operation and for Precautions to be Taken to Avoid Possible Exposure to Excessive Microwave Energy. 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. (a) inform the manufacturer, importer or assembler, (b) repair the unit at no cost to the owner, (c) attempt to ascertain the cause of the excessive leakage, (d) 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 and CDRH immediately.

CAUTION MICROWAVE RADIATION PERSONNEL SHOULD NOT BE EXPOSED TO THE MICROWAVE ENERGY WHICH MAY RADIATE FROM THE MAGNETRON OR OTHER MICROWAVE GENERATING DEVICE IF IT IS IMPROPERLY USED OR CONNECTED. ALL INPUT AND OUTPUT MICROWAVE CONNECTIONS. WAVEGUIDES FLANGES AND GASKETS MUST BE SECURED. NEVER OPERATE THE DEVICE WITHOUT A MICROWAVE ENERGY ABSORBING LOAD ATTACHED. NEVER LOOK INTO AN OPEN WAVEGUIDE OR ANTENNA WHILE THE DEVICE IS ENERGIZED.

3

SPECIFICATIONS
MODEL POWER SUPPLY POWER CONSUMPTION MICROWAVE GRILL COMBINATION 1100 W 2450MHz 560X344X471mm (22.0X13.5X18.5 in.) 369X246X394mm (14.5X9.7X15.5 in.) APPROX. 18kg (39.7 lbs.) 99min. 99sec. MICROWAVE 10 LEVELS 1.3 Cu. Ft KOR-1B4H0A 120V~60HZ, SINGLE PHASE WITH EARTHING 1500 W

MICROWAVE ENERGY OUTPUT MICROWAVE FREQUENCY OUTSIDE DIMENSIONS (W X H X D) CAVITY DIMENSIONS (W X H X D) NET WEIGHT TIMER FUNCTION SELECTIONS POWER SELECTIONS CAVITY VOLUME * Specifications are subject to change without notice.

4

EXTERNAL VIEW
1. OUTER DIMENSION

560

471

M/W

DEF TIMER LOCK

lb

POPCORN MORE BEVERAGE

FROZEN PIZZA

DINNER PLATE LESS

FRESH FROZEN VEGETABLE VEGETABLE POULTRY FISH

MEAT

POWER

DEFROST

1 4 7
KITCHEN TIMER

2 5 8 0

3 6 9
CLOCK

STOP/CLEAR

START/ SPEEDY COOK

5

344

2. FEATURE DIAGRAM

2 1

4

6

M/W

DEF TIMER LOCK

lb

POPCORN MORE BEVERAGE

FROZEN PIZZA

DINNER PLATE LESS

FRESH FROZEN VEGETABLE VEGETABLE POULTRY FISH

MEAT

POWER

DEFROST

1 4 7
KITCHEN TIMER

2 5 8 0

3 6 9
CLOCK

7

STOP/CLEAR

START/ SPEEDY COOK

3 9

5 8 0

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. SPATTER SHIELD Protects the microwave outlet from splashes of cooking foods. 5. OVEN LAMP Automatically turns on during oven operating. 6. SAFETY INTERLOCK SYSTEM 7. CONTROL PANEL 8. GLASS COOKING TRAY Made of special heat resisant glass. The tray must always be in proper position before operating. Do not cook food directly on the tray. 9. OVEN FRONT PLATE 10. ROLLER GUIDE Supports the glass cooking tray.

6

3. CONTROL PANEL

2
M/W DEF TIMER LOCK lb

3
POPCORN FROZEN PIZZA DINNER PLATE LESS FRESH FROZEN VEGETABLE VEGETABLE POULTRY FISH

4 6 7

MORE BEVERAGE

5

MEAT

POWER

DEFROST

8 1 0 w

1 4 7

2 5 8 0

3 6 9
CLOCK

9 q

KITCHEN TIMER

STOP/CLEAR

START/ SPEEDY COOK

1. Time set pad - Used to set the cooking time and the present time. 2. Display - Cooking time, power level, indicators and present time are displayed. 3. One touch - Used to cook or reheat specific quantities of food. 4. More - Used to add time to cooking. 5. Less - Used to remove time from cooking. 6. Auto Defrost - Used to defrost foods.(for weight) 7. Power - Used to set power level. 8. Defrost - Used to defrost foods.(for time) 9. Kitchen Timer - Used as a minute timer, delay cooking, hold setting after cooking. 10. Clock - Used to set clock. 11. Stop/Clear - Used to stop the oven operation or to delete the cooking data. 12. Start/Easy cook - Used to start the oven and also used to set a reheat time.

7

INSTALLATION
1. Steady, flat location.
This microwave oven should be set on a steady, flat surface.

2. Leave space behind and side.
All air vents should be kept a clearance. If all vents are covered during operation, the oven may be overheated and, eventually, cause oven 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 15 amperes, 120Volts, 60Hz grounded outlet. 1. A short power-supply cord is provided to reduce the risks resulting from becoming entangled in or trippping over a longer cord. 2. Longer cord sets or extension cords are available and may be used if care is exercised in their use. 3. If a long cord or extension cord is used: 1) The marked electrical rating of the cord set or extension cord should be at least as great as the electrical rating of the appliance. 2) The extension cord must be a grounding type 3-wire cord. 3) The longer cord should be arranged so that it will not drape over the counter top or tabletop where it can be pulled on by children or tripped over unintentionally.

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.

8

OPERATIONS AND FUNCTIONS
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. 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. 5. Each time a pad is touched, a BEEP will sound to acknowledge the touch. 6. The oven automatically cook on full power unless set to a lower power level. 7. The display will show : 0 when the oven is plugged in. 8. Time clock returns to the present time when the cooking time ends. 9. 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 information is retained. 10. 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 until the door is completely closed or the program has been reset. Make sure the oven is properly installed and plugged into the electrical outlet. Wattage output chart The power level is set by touching the POWER pad. The chart shows the display, the power level and the percentage

Touch POWER pad. Once Twice 3 times 4 times 5 times 6 times 7 times 8 times 9 times 10 times 11 times

Power level(Display) P-HI P-90 P-80 P-70 P-60 P-50 P-40 P-30 P-20 P-10 P-00

Approximate Percentage of Power 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

9

DISASSEMBLY AND ASSEMBLY
- 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 wear rubber gloves when servicing the high voltage side. 3. Discharge the high voltage capacitor before touching any oven components or wiring. (1) Check the grounding. Do not operate on a two-wire extension cord. The microwave oven is designed to be used while grounded. It is imperative, therefore, to make sure it is grounded 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, 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 20A fuse is blown 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, take care when touching or replacing high potential parts because of electrical shock or exposing microwave. These parts are as follows - HV Transformer, Magnetron, HV Capacitor.

10

1. To remove cabinet
1) Remove three screws on cabinet back. 2) Push the cabinet backward.

2. To remove door assembly
1) Remove two 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.

11

3. To remove door parts.
A10

A11 A09 A14 A07

A05 A04

A12 A13 A08

A03

A01 A02

A06

REF NO. A01 A02 A03 A04 A05 A06 A07 A08 A09 A10 A11 A12 A13 A14

PART CODE 3512604200 3515307400 3511605510 3511605400 3511605700 3511605600 3512204750 7001503511 3517004090 3515204900 3516602100 3513101200 3515101800 3512302310

PART NAME HANDLE DOOR SUPPORTER HANDLE DECORATOR DOOR *U DECORATOR DOOR *T DECORATOR DOOR *L DECORATOR DOOR *R FRAME DOOR SCREW MACHINE BARRIER-SCREEN *O STOPPER HINGE *T AS DOOR-PLATE HOOK SPRING HOOK GASKET DOOR

DESCRIPTION ALUMINUM KOC-1B4K0S STS304 T0.5 STS304 T0.5 STS304 T0.5 STS304 T0.5 ABS PAN 5X35 MFZN TEMP GLASS T3.2 KOC-1B4K0S SBHG-1A T0.7 POM PW1 PP

Q'TY 1 2 1 1 1 1 1 2 1 1 1 1 1 1

REMARK

(1) Remove the gasket door(A14) from door plate. (2) Remove two screws(A08) from door plate. (3) Remove the door handle (A01) and handle supporter (A02) from door plate. (4) Remove the four door decorators (A03~A06) from door frame. (5) Remove the door frame (A07) from door plate. (6) Remove the stopper hinge top(A10) from door plate. (7) Remove the spring(A13) and the hook(A12). (8) Remove the barrier screen outer(A09) from door frame. (9) Reverse the above steps for reassembly.

12

4. Method to reduce the gap between the door seal and the oven front surface.
(1) To reduce gap located on part `A'. Loosen two screws on stopper hinge top, and then push the door to contact the door seal to oven front surface. Tighten two screws. (2) 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.
M/W DEF TIMER LOCK lb

A

POPCORN

FROZEN PIZZA

DINNER PLATE LESS

MORE FRESH
VEGETABLE

BEVERAGE

FROZEN
VEGETABLE

MEAT

POULTRY

FISH

POWER

DEFROST

1 4 7
KITCHEN TIMER

2 5 8 0

3 6 9
CLOCK

STOP/CLEAR

START/ SPEEDY COOK

B

NOTE : A small gap may be acceptable if the microwave leakage does not exceed 4mW/cm2.

13

5. To remove control panel parts.

B03

B05 B04

B02

B01

REF NO. B01 B02 B03 B04 B05

PART CODE 3518523400 3511607600 3516727000 3514326500 7122401211

PART NAME SWITCH MEMBRANE DECORATOR C-PANEL CONTROL PANEL PCB AS SCREW TAPPING

DESCRIPTION KOR-1B4H0A STS430 HL T0.5 ABS AF-348, VT-0826 KOR-1B4H0A T2S TRS 4X12 MFZN

Q'TY 1 1 1 1 4

REMARK

(1) Remove the screw which secure the control panel, push up two snap fits and draw forward the control panel assembly. (2) Remove four screws which secure the PCB assembly to control panel. (3) Disconnect membrane tail from the connector of the PCB assembly. (4) Detach membrane from the control panel. (5) Pull out the decorator c-panel from the control panel. (6) Reverse the above steps for reassembly.

14

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.

x 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/cm2 for a fully assembled oven with door normally closed.

15

8. To remove wind guide assembly.
1) Remove a screw which secure the wind guide assembly. 2) Draw forward the wind guide assembly. 3) Pull the fan from the motor shaft. 4) Remove two screws which secure the motor shaded pole. 5) Remove the motor shaded pole. 6) Reverse the above steps for reasembly.

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.

16

INTERLOCK MECHANISM AND ADJUSTMENT
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 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. The lock lever presses the button of the secondary interlock switch to bring it under ON condition. 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 changed (NC condition) after other switches are opened. (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 two mounting screws. NOTE : Microwave emission test should be performed after adjusting interlock mechanism. If the microwave emission exceed 4mW/cm2, readjust interlock mechanism.

17

TROUBLE SHOOTING 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 tranformer, 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.

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.

(TROUBLE 1) Oven does not operate at all : any inputs can not be accepted.

CONDITION Fuse blows.

CHECK

RESULT

CAUSE Malfunction of interlock monitor switch

REMEDY Replace NOTE 1

Check continuity of interlock monitor switch with door closed Replace fuse

Continuity No Continuity

Check continuity of of primary interlock switch contact with door partially open until interlock monitor switch contact close

Continuity

Shorted contacts of primary interlock switch.

Replace NOTE 1

Check continuity of primary winding of low voltage transformer

0 or infinite Approx. 150~310 (normal)

Defective low voltage transformer

Replace

Disconnect one side of the lead wire connected form high voltage transformer to the high voltage capacitor and operate the unit

Normal

Defective high voltage capacitor

Replace

Fuse again blows

Defective high voltage transformer

Replace

18

CONDITION Outlet has proper voltage Fuse does not blow.

CHECK

RESULT No Continuity

CAUSE Defective magnetron

REMEDY Replace

Check continuity of magnetron

Check continuity of power supply cord

No Continuity

Open power supply cord

Replace

Normal

Defective touch control circuit

Replace

Display do not shown countdown

Malfunction of secondary interlock switch

Replace

NOTE 1 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.

CONDITION Turn table motor and oven lamp do not turn on

CHECK Check continuity of primary interlock switch

RESULT No Continuity

CAUSE Malfunction of primary interlock switch

REMEDY Adjust or replace

Check continuity of secondary interlock switch

No Continuity

Malfunction of secondary interlock switch

Adjust or replace

Check D.C. voltage being supplied to RELAY (RY2) coil

0V

Defective touch control circuit

Replace

Approx. 15 VDC

Faulty contacts of RELAY (RY2) or open relay coil

Replace

19

(TROUBLE 3) No microwave oscillation even though fan motor rotates.

CONDITION No microwave oscillation

CHECK

RESULT Continuity

CAUSE

REMEDY

Check continuity of high voltage capacitor terminals with wires removed

Defective high voltage transformer

Replace

Check continuity of high voltage rectifier in forward and backward direction with DC megger

Continuity in backward direction Continuity

Defective high voltage rectifier

Replace

Connect megger leads to magnetron terminal and magnetron body

Defective magnetron

Replace

Check resistance of primary and secondary coil of high voltage transformer

0 or

Defective high voltage transformer

Replace

Check continuity of magnetron with wires removed

No Continuity

Defective magnetron

Replace

Check continuity of filament terminal of high voltage transformer

No Continuity

Defective high voltage transformer

Replace

0V Check D.C. voltage being supplied to RELAY (RY1) coil Defective touch control circuit

Replace

Approx 15 VDC

Faulty contacts or RELAY (RY1) or open relay coil

Replace

20

(TROUBLE 4) The following visual conditions inditions indicate a probable defective touch control circuit or membrane switch assembly 1. Incomplete segments, 1) Segments 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 is not on when they should be. 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 noticeable 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.
M/W DEF TIMER LOCK lb

CONDITION Display does not show programming at all, even if keyboard is touched.

CHECK Check rach pad for continuity of the membrane keyboard for the following keyboard check procedure

RESULT Normal

CAUSE Malfunction of touch control circuit of control box sub-assembly Malfunction of the membrane keyboard

REMEDY Replace control box sub-assembly

Abnormal

Replace the membrane keyboard

NOTE Before following the particular steps listed above in the trouble shooting guide for the membrane keyboard's, failure, please check for the continuity of each wire-harness between the membrane keyboard and P.C.B. assembly.

21

MEASUREMENT AND TEST
1. MEASUREMENT OF THE MICROWAVE POWER OUTPUT
Microwave output power can be checked by indirectly mmeasuring the temperature rise of a certain amount of water exposed to the microwave as directed below. PROCEDURE 1. Microwave power output measurement is made with the microwave oven supplied at rated voltage and operated at its maximum microwave power setting with a load of 100 5cc of potable water. 2. The water is contained in a cylindrical borosilicate glass vessel having a maximum material thickness of 3 mm and an outside diameter of approximately 190 mm. 3. The oven and the empty vessel are at ambient temperature prior to the start of the test. The initial temperature of the water is 10 2C (50 3.6F). If is measured immediately before the water is added to the vessel. After addition of the water to the vessel, the load is immediately placed on the center of the shelf, which is in the lowest normal position. 4. Microwave power is switched on. 5. Heating time should be exactly A seconds. (Refer to table as following) Heating time is measured while the microwave generator is operating at full power. The filament heatup time for magnetron is not included. 6. The initial and final temperature of water is selected so that the maximum difference between the ambient and final water temperature is 5K. 7. The microwave power output P in watts is calculated from the following formula: P = 4187 X T/t T is difference between initial and final temperature. t is the heating time. The power measured be B (Refer to SPECIFICATIONS) W 10.0 %.

CAUTION 1. Water load should be measured exactly to 1 liter. 2. Input power voltage should be exactly specified voltage (Refer to SPECIFICATIONS). 3. Ambient temperature should be 20 2C (68 3.6F)

Heating time for power output: A (second) B (W) 70 600 64 650 60 700 56 750 52 800 49 850 47 900 44 950 42 1000 40 1050 38 1100

22

2. MICROWAVE RADIATION TEST
CAUTION 1. Make sure to check the microwave leakage before and after repair of adjustment. 2. Always start measuring of an unknown field to assure safety for operating personnel from microwave energy. 3. Do not place your hands into any suspected microwave radiation field unless the safe density level is known. 4. Care should be taken not to place the eyes in direct line with the source of microwave energy. 5. Slowly approach the unit under test until the radiometer reads an appreciable microwave leakage from the unit under the test.

PROCEDURE 1. Prepare Microwave Energy Survey Meter, 600cc glass beaker, and glass thermometer 100C (212F).
M/W DEF TIMER LOCK lb

POPCORN

FROZEN PIZZA

DINNER PLATE LESS

MORE

2. Pour 275cc 15cc of tap water initially at 20 5C (68 9F) in the 600 cc glass beaker with an inside diameter of approx. 95 mm(3.5 in.). 3. Place it at the center of the tray and set it in a cavity. 4. Close the door and operate the oven. 5. Measure the leakage by using Microwave Energy Survey Meter with dual ranges, set to 2450MHz.

BEVERAGE

FRESH
VEGETABLE

FROZEN
VEGETABLE

MEAT

POULTRY

FISH

POWER

DEFROST

1 4 7
KITCHEN TIMER

2 5 8 0

3 6 9
CLOCK

STOP/CLEAR

START/ SPEEDY COOK

1) Measured radiation leakage must not exceed the value prescribed below. Leakage for a fully assembled oven with door normally closed must be less than 4mW/cm2. 2) When measuring the leakage, always use the 5 cm (2 in.) space cone with probe. Hold the probe perpendicular to the cabinet and door. Place the space cone of the probe on the door, cabinet, door seem, door viewing screen, the exhaust air vents and the suction air vents. 3) Measuring should be in a counter-clockwise direction at a rate of 1 in./sec. If the leakage of the cabinet door seem is unknown, move the probe more slowly. 4) When measuring near a corner of the door, keep the probe perpendicular to the areas making sure the probe end at the base of the cone does not get closer than 2 in. from any metal. If it does not, erroneous reading may result.

23

3. COMPONENT TEST PROCEDURE
High voltage is present at the high voltage terminal of the high voltage transformer during any cooking cycle. It is neither necessary nor advisable to attempt measurement of the high voltage. Before touching any oven components or wiring, always unplug the oven from its power source and discharge the capacitor. 1. High voltage transformer 1) Remove connections from the transformer terminals and check continuity. 2) Normal readings should be as follows : Secondary winding ... Approx. 110 10% Filament winding ... Approx. 0 Primary winding ... Approx. 1 2. High voltage capacitor 1) Check continuity of capacitor with meter on the highest OHM scale. 2) A normal capacitor will show continuity for a short time, and then indicate 10M once the capacitor charged. 3) A shorted capacitor will show continuous continuity. 4) An open capacitor will show constant 10M. 5) Resistance between each terminal and chassis should be infinite. 3. High voltage diode 1) Isolate the diode from the circuit by disconnecting the leads. 2) With the ohmmeter set on the highest resistance scale measure the resistance across the diode terminals. Reverse the meter leads and again observe the resistance reading. Meter with 6V, 9V or higher voltage batteries should be used to check the front-back resistance of the diode, otherwise an infinite resistance may be read in both directions. A normal diode's resistance will be infinite in one direction and several hundred k in the other direction. 4. Magnetron For complete magnetron diagnosis, refer to "Measurement of the Microwave Power Output." Continuity checks can only indicate and open filament or a shorted magnetron. To diagnose for an open filament or a shorted magnetron, 1) Isolate magnetron from the circuit by disconnecting the leads. 2) A continuity check across magnetron filament terminals should indicate 0.1 or less. 3) A continuity check between each filament terminal and magnetron case should read open. 5. Fuse If the fuse in the primary and monitor switch circuit is blown when the door is opened, check the primary and monitor switch before replacing the blown fuse. In case the fuse is blown by an improper switch operation, replace the defective switch and fuse at the same time. Replace just the fuse if the switches operate normally.

24

WIRING DIAGRAM

25

PRINTED CIRCUIT BOARD
1. CIRCUIT CHECK PROCEDURE
1. Low voltage transformer check The low voltage transformer is located on the P.C.B. Measuring condition: Input voltage: 120V / Frequency: 60Hz Terminal Voltage 4-7 LOAD AC 12.6 V NO LOAD AC 14.7 V

NOTE 1. Refer to Ciruit Diagram (point 4). 2. Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source voltage. 3. The allowable tolerance of the secondary voltage is within 5% of nominal voltage.

2. Voltage Check - Key check point NO 1 2 CHECK POINT IC1 PIN 2, 21, 30, 34 IC1 PIN 35 -5VDC REMARK

T : 16.67ms(60Hz) 3 IC1 PIN 31 OR 32

T : 250 ns(4MHz)

- Check method NO 1 2 MEASURE POINT MP1 MP2 WAVE FORM DC -5V0.25V DC -12V2.0V REMEDY Replace VL1, EC1 Replace EC2, D12,13,14 REMARK NO LOAD NO LOAD

NOTE Each measure point must be measured with GND points.

26

MP1

MP2

Mesure point

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3. When there is no microwave oscillation 1) When touching START pad, oven lamp does not turn on. Fan motor do not rotate, but cook indicator in display comes on. Cause : RELAY 2 does not operate. refer to Circuit Diagram (point 3) - Check method POINT STATE RELAY 2 ON RELAY 2 OFF A -5VDC GND B GND -12VDC

2) When touching START pad, oven lamp turns on. Fan motor and turntable rotate and cook indicator in display comes on. Cause : RELAY 1 does not operate. refer to Circuit Diagram (point 2) - Check method POINT STATE RELAY 1 ON RELAY 1 OFF A -5VDC GND B GND -12VDC

4. When the door is opened during operation the count down timer does not stop. refer to Circuit Diagram (point 1) - Check method POINT STATE 1) DOOR OPEN 2) DOOR CLOSED CHECK NO 1 HETHOD Check the stage(ON, OFF) of the secondary interlock switch by resistance measurement. A OPEN CLOSE B -5VDC GND REMEDY Replace door open monitor switch.

5. When the digital clock does not operate properly. refer to Circuit Diagram (point 5) POINT A WAVE FORM

T: 16.67 ms(60Hz)

If clock does not keep exact time, you must check resistor R15,16, zener diode ZD1.

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2. P.C.B. CIRCUIT DIAGRAM

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3. P.C.B. LOCATION NO. NO 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 BUZZER C ARRAY CAPACITOR ELEC CPAPCITOR ELEC CONNECTOR WAFER CONNECTOR WAFER CONNECTOR WAFER DIODE RECTIFY DIODE RECTIFY DIODE ZENER DIODE ZENER LED DISPLAY PCB MAIN R ARRAY RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR REGULATOR TRANSISTOR TRANSISTOR TRANS POWER WIRE COPPER WIRE COPPER IC MICOM RESONATOR CERA SW RELAY SW RELAY CAPACITOR CERA CAPACITOR CERA NAME SYMBOL BZ1 CA1 EC1 EC2 CN1 CN3 CN2 D1~6, 9~12,15 D13, 14 ZD1 ZD2 DP1 M158 RA1 R1~R7 R8, 10, 12, 14, 22 R11, 20, 21 R13 R15~16 R17 R18 R19 VL1 Q1~5, 9~11 Q6 LVT1 J1~3,5~8,10~12,17~21 SJ3, 5 IC1 CR1 RY1 RY2 C6 C1, C3~C5, C7 SPECIFICATION BM-20K 7P(6) 102 M 50V 50V RS 1F 25V RSS 1000F YW396-02AV YW396-05AV FCZ 254-11 1N4148 1N4004A UZ-5.1BSB UZ-3.9BSB DDG-631H 81.5X139.9 7P(6) 1/8 100K J 1/6W 220 5% 1/6W 1K 5% 1/6W 100K 5% 1/6W 200 5% 1/6W 10K 5% 1/6W 510 5% 1/6W 1M 5% 1/4W 51 5% MC7905C KRA-106M KTA-1266Y DMR-631P 1/0.52 TIN COATING 1/0.52 TIN COATING TMP47C440BN KBR-4.0MSTF G5G-1A DC 12V CS11-12SH 1C 1P 102 50V Z AXIAL 104 50V Z AXIAL PART CODE 3515600100 CN6XB-102M CEXE1H109V CEXF1E102V 3519150520 3519150510 441M367160 DZN4148--DZN4004A-DZUZ5R1BSB DZUZ3R9BSB DDDG631H01 3514315410 RA-87X104J RD-AZ221JRD-AZ102JRD-AZ104JRD-AZ201JRD-AZ103JRD-AZ511JRD-AZ105JRD-4Z510J1MC7905C-TZRA106M-TZTA1266Y5EPU035302 85801052GY 85801052GY 13GS1B4H00 5PKBR40MKS 5SC0101121 5SC0101128 CCZB1H102K CCZF1H104Z Q'TY 1 1 1 1 1 1 1 11 2 1 1 1 1 1 7 5 3 1 3 1 1 1 1 8 1 1 15 2 1 1 2 1 1 5

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EXPLODED VIEW AND PARTS LIST
1. DOOR ASSEMBLY
Refer to Disassembly and assembly

2. CONTROL PANEL ASSEMBLY
Refer to Disassembly and assembly

3. TOTAL ASSEMBLY

F01

F02

F03

F04

F06

F07

F08

F45

F44 F43 F42 F41 F40 F10 F11 F12

F13 F05 F09 F15 A00 F16 F17 B00 F18 F19 F14

F20

F21

F39

F38

F37

F36

F35

F34

F33 F32

F31

F30

F29 F28 F27

F26

F25

F24

F23

F22

31

REF NO A00 B00 F01 F02 F03 F04 F05 F06 F07 F08 F09 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31 F32 F33 F34 F35

PART CODE 3511716000 3516727200 3510806800 3516004100 3516114400 7122401211 7122401211 7122401011 35113UANT5 7122401211

PART NAME DOOR AS CONTROL PANEL AS CABINET SPECIAL SCREW CAVITY AS SCREW TAPPING SCREW TAPPING SCREW TAPPING CORD POWER AS SCREW TAPPING FUSE KOR-1B4H0A KOR-1B4H0A STS430 T0.5 HL

DESCRIPTION

Q'TY 1 1 1 4 1 1 1 1 1 1 1

T1 TRS LR4 POLE 4X10 MFZN KOR-1B4H0A T2S TRS 4*12 MFZN T2S TRS 4*12 MFZN T2S TRS 4*10 MFZN 3X14 AWG 60X60 120-RTML T2S TRS 4*12 MFZN

7121403011 3963822200 3512515300 3511800100 3518003500 3516003800 7272400811 3513003200 3518302300 3518400110 3518118600 3516003700 3510313520 7112401011 3512101400 7272400811 3515202800 3512717400 3513702100 4415A17352 4415A66600 4415A17352 4415A66910 3513700800 3513816000 3513601500

SCREW TAPPING MOTOR SHADED POLE GUIDE WIND FAN MAGNETRON SPECIAL SCREW SCREW TAPTITE HOLDER HV CAPACITOR CAPACITOR HV DIODE HV TRANS HV SPECIAL SCREW BASE SCREW TAPPING FOOT SCREW TAPTITE STOPPER HINGE *U HARNESS MAIN LEVER SW MICRO SW MICRO SW MICRO SW MICRO SW MICRO LEVER LOCK LOCK LAMP

T2S PAN 4X30 MFZN 120V 30W OEM-15DWX1-B07 PP PP GF 20 RM259(JF) T2 FLANGE 5X8 MFZN TT3 TRS 4X8 MFZN SECC T0.6 2100VAC 1.10UF #187 HVR-1X-70B 12KV #187 DW-R11A0-1BT T2 FLANGE 5X8 MFZN SBHG T0.8 T1 TRS 4X10 MFZN DASF-310 TT3 TRS4X8 MFZN KOR-121M0A KOR-131G0A POM VP-533A-OF SPNO #187 200G VP-532A-OF/SPNO #187 200G VP-533A-OF SPNO #187 200G VP-531A-OF/SZ,-V16-FA-61 POM PP BL 120V 25W T25 C5A H187

2 1 1 1 1 1 1 1 1 1 1 4 1 6 4 1 1 1 1 1 1 1 1 1 1 1

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REF NO F36 F37 F38 F39 F40 F41 F42 F43 F44 F45

PART CODE 7121400611 3966820200 3518905300 3513003400 7272400811 3511408300 3517402000 3514700710 3512517200 3517207600

PART NAME SCREW TAPPING MOTOR SYNCRO THERMOSTAT HOLDER THERMOSTAT SCREW TAPTITE COVER WAVE GUIDE COUPLER ROLLER GUIDE ROLLER TRAY

DESCRIPTION T2S PAN 4X6 MFZN 120V 2W GM-16-12F17 OFF:75 ON:65 H #187 NR PP(NATURAL) TT3 TRS 4X8 MFZN MICA T0.35 QUESTRA TEFLON PP DIA:340 1300G

Q'TY 1 1 1 1 2 1 1 3

1

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DAEWOO ELECTRONICS CO., LTD.
686, AHYEON-DONG MAPO-GU SEOUL, KOREA C.P.O. BOX 8003 SEOUL, KOREA TELEX: DWELEC K28177-8 CABLE: "DAEWOOELEC"

S/M NO.:R1B4H0A001

PRINTED DATE: Oct. 2001