service manual.cdr
Contents
1. BLACK ss DECKER Microwave Oven CAUTION This Device is to be Serviced Only by Properly Qualified Service Personnel Consult the Service Manual for Proper Service Procedures to Assure Continued compliance with the Federal Performance Standard for Microwave Ovens and for Precautions to be Taken to Avoid Possible Exposure to Excessive Microwave Energy CONTENT Chapter 1 Microwave Oven Composition and Operating Principle 1 Microwave Oven Composition 2 Microwave Oven Operating Principle 3 Microwave Oven Circuit Principle Chapter 2 Microwave Oven Common Faults and Maintenance 1 Attention Points on Maintenance Microwave Oven Parts Assembling and Disassembling Process 2 3 4 Microwave Oven Test and Trial Run after Repairing Microwave Oven Common Faults and Diagnosis to Them Appendix 1 Microwave Oven Dismounting Exploded View Appendix 2 Microwave Oven Specifications Chapter 1 Microwave Oven Composition and Operating Principle 1 Microwave Oven Composition 1 Fire Door Safe Lock System 5 Glass Turntable 2 Observation Window 6 Control Panel 3 Spiracle 7 Rollaway Nest 4 Swivel 5 3 6 Microwave Oven is mainly composed of heating room microwave source and control panel Heating room is composed of cavity combination turntable system and fire door Microwave source is mainly composed of magnetron transformer high voltage capacitor and high voltage diode Co2. never operate it with power on 2 Never open the housing to check or repair high voltage transformer high voltage winding and magnetron filament winding while the unit is on if test or replacement is in need you should first draw off power plug discharge high voltage capacitor to avoid high voltage electric shock and microwave radiation 3 When you are checking the unit please never insert some metal such as screw or conductor into cracks of the fire door never keep impurity such as tools in the oven to avoid short circuit spark or electric shock which is caused by their reaching charged parts of the unit at the same time effective radioactive antenna can not coming into being to cause excessive microwave leakage 4 When you disassemble turntable motor or replace transformer never make door surface against the earth to place it to avoid being damaged or deforming You should place it on rubber cushion without impurity its flank inclined 5 You should fix the screw firmly while repairing Do avoid inclination and slippage otherwise you should reassemble it or replace screw or take other measures 6 Be sure interconnecting devices are connected properly and firmly when you replace capacitor components If any is loose please clamp the plug firmly with sharp nose pliers and plug it to the right place 7 When you have repaired it please fill in guarantee card in detail as form 2 Microwave Oven Parts Assemblin
3. ectric leakage It becomes damaged or aging because of long term operation Insulation resistance of every motor transformer and ground is less than 2 megohm Overhaul or replace it Check electric leakage place with megameter repair or replace damaged components 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 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 compartments check the magnetron wave guide or transmission line and cavity for proper alignment integrity and connections Q lt 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 c A Microwave leakage check to verify compliance with the Federal performance standard should be performed on each oven p
4. en it is turned on 2 Microwave oven is on lamp is on turntable and fan works but food in it can not be heated 3 Microwave oven can heat but the oven lamp is off 4 Microwave oven can heat bu turntable can not work 4 Microwave oven can heat within 2 to 3 minutes can not heat if time exceeds 4 minutes 1 Fuse wire is broken 2 Capacity transformer primary or secondary short circuit 3 Capacitor to earth disruption or polar to polar disruption 4 Monitor switch can not be turned off 5 Interlock switch is on 6 Loose contact between power plug and outlet 7 Gate stop is broken 1 Power transformer primary or secondary disconnection filament is disconnected 2 Magnetron filament disconnected magnetron magnetic steel cracking or magnetron air leakage 3 Power timer can not work 4 Plug of magnetron or capacitor is loose 1 The oven lamp can not work 2 Plug is loose 1 Something is wrong with the motor 2 Plug is loose 3 Connecting cracking axle sleeve 1 Fan motor winding disconnected 2 Fan motor blade is loose 3 Fan motor plug is loose 4 Motor rotation axle and bearing grip each other 5 Cooling air passage blocked 1 Replace the fuse wire 2 Replace power transformer 3 Replace capacitor 4 Replace monitor switch 5 Replace interlock switch 6 Adjust the connection or replace it 7 Replace gate stop 1 Replace power transfo
5. g and Disassembling Process 1 Assembling and Disassembling of housing 1 Unscrew fixed screw of housing 2 Push the housing backward to detach it 3 Installation is reverse to above illustration make housing turnup edge slip forward along cavity combination pay attention to fit both sides of housing up turnup edge to cavity combination 2 Assembling and Disassembling of Timer 1 Detach the housing and pull out timer knob 2 Pull out connector plug of timer 3 Unscrew screws fixing control panel and detach the control panel 4 Installation is reverse to above illustration pay attention not to make principal axis and knob of rub against control panel 5 Check timer assembling after installation Turn timer clockwise to some angle and return to 0 position you may hear ring bell if there is deviation please readjust the screw to ensure concentricity of timer principal axis and panel hole 3 Assembling and Disassembling of Safe Switch Board 1 Detach the housing pull micro switch wire plug out of switch board 2 Unscrew 2 screws fixing switch board and detach switch board NNN 3 Pull micro switch out of switch board 4 Installation is reverse to above illustration pay attention to check whether micro switch is installed to proper position The position should be right wiring plug should be firmly fixed the fire door can be opened or closed flexibly otherwise you should readjust 2 screws fixing switch b
6. ntrol panel consists of timer power selector and so on Computer type control panel mainly consists of computer board 2 Microwave Oven operating principle Microwave oven operating principle block diagram is as follows MAGNETRON WAVEGUIDE HEATING ROOM MULTIVOLTAGE T CONTROL SYSTEM POWER RECTIFICATION CIRCUIT Microwave Oven supplies magnetron constant and reliable operating voltage and operating time through control system and multivoltage rectification circuit after power is on Control system also acts as safety monitor of magnetron The controlled microwave produced by magnetron is transmitted into microwave heating room through wave guide part of which directly enters inside food after entering heating room the rest enters food after repeated reflection by cavity wall it is absorbed to produce heat for completing all operations such as heating cooking and sterilization 3 Microwave Oven Circuit principle NOISEFILTER SW1 SWA sw2 rr m rr i SW1 Timer Time Control Switch L Lamp SW2 Timer Fire Control Switch T Timer Motor SWA Door 1 Safe Switch MF Fan Motor SWB Door 3 Safe Switch MT Turntable Motor SWC Door 3 Safety Monitoring Switch Chapter 2 Microwave Oven Common Faults and Maintenance 1 Attention points on maintenance 1 When microwave oven needs checking or dismounting you should pull out the plug to shut off the power letting microwave wipe stop working To guarantee personal safety
7. oard 4 Assembling and Disassembling of Motor 1 Take out glass turntable swivel coupler and so on 2 Turn microwave oven upside down detach middle cover with pliers and screwdriver 3 Unscrew 2 screws fixing turntable motor pull out wiring plug take out the motor 4 4 Installation is reverse to above illustration 5 Assembling and Disassembling of Transformer 1 Detach the housing Turn microwave oven upside down Unscrew 4 screws fixed in baseboard and take it together with transformer Installation is reverse to above illustration 6 Assembling and Disassembling of Magnetron 1 Detach the housing 2 Pull out wiring plug of magnetron and temperature regulator 4 J 2 3 Unscrew screws fixing air intake hood 4 Unscrew screws fixing magnetron 5 Installation is reverse to above illustration 7 Assembling and Disassembling of Fire Door 1 Detach the housing 2 Unscrew hinge screws in fire door 3 Raise the fire door a little to detach it 4 Attention points on assembling fire door a Smear a little silicone grease on rotating part of the door b Fire door should fit switch board well in door installation to be sure it can be opened or closed flexibly and door safe switch work well c Cracks of fire door should be as wide as possible The door should rotate flexibly Inclination or stagnation is forbidden 5 Installation Is reverse to above illustration The unit should be tested wi
8. rior to release to the owner
9. rmer 2 Replace magnetron 3 Replace power device timer or micro switch 4 Replace it 1 Replace the lamp 2 plug the plug 1 Replace turntable motor 2 Plug the plug 3 Replace connecting axle sleeve 1 Replace the fan motor 2 Replace the fan blades 3 Plug the plug 4 Overhaul it 5 Check it 6 Microwave oven is on it 1 High voltage diode 1 Replace the high voltage hums but can not heat disruption diode 7 Microwave oven can heat 1 Power transformer core is 1 Replace the Power but neighs loudly loose transformer 8 Microwave oven microwave leakage is serious Door is deformed Door metal loop cracking Crack of the door is wide Cavity soldered dot is loose Magnetron fixing screw is loose Wave guide connection oxidation Overhaul and reshape it Replace the door Adjust the space between cracks of the door Replace the cavity body Screw the fixing screw Scrape oxide layer and screw the screw Magnetron copper wire cushion ring is thin and Thicken the copper cushion ring waveguide connector contacts ground loosely 9 Microwave oven door can not be opened Space between door axle and axle hole becomes wider and door inclined one Adjust door hinge to rectify the door Replace the gate stop way because of long term damage and corrosion Gate stop is broken 10 Button is loose 11 Microwave oven el
10. th microwave leakage meter after installation so as to avoid excessive microwave leakage 3 Microwave Oven Test and Trial Run after Repairing 1 Safe grounding microwave oven needs good grounding to avoid clectric shock and disturbance 2 Parts should be fixed firmly electric components should be connected properly each plug and connecting device should be connected firmly looseness is forbidden 3 Never keep impurity in the oven 4 Never test microwave oven without any loading you should put food such as a cup of tea in it to prevent magnetron from burning on condition that microwave can be absorbed nowhere 5 Never detach the housing to test the unit 6 Insulation property Use 500 volte megohm meter to check whether insulation resistance between power plug and uncharged metal part of housing is over 20 megohm 7 After overall unit is heavy repaired such as replacing cavity combination Fire door should be measured with microwave power leakage meter in any place 5 centimeter far from microwave oven microwave leakage power density should not exceed 1 mw cm 8 Following safety check is necessary before power is on Check whether fire door can be opened and closed well Il Check whether fire door and seal surface plug and bolt are damaged or loosen Ill Check whether safety device can work well 4 Microwave Oven Common Faults and Diagnosis to Them 22 1 Three no happens to microwave oven wh
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