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Tools normally used for TV servicing are sufficient. 

Standard tools are listed below. 

• Diagonal pliers 

• Long nose pliers 

• Phillips screwdriver 

• Flat blade screwdriver 

• Wrench (size 5mm) 

• Nutdriver (size 5mm) 

• Adjustable wrench 

• Soldering iron 

• Solder 

• Vinyl insulation tape 

• Polishing cloth 

 

 

 

and should repair any 

unit found to have excessive emission levels at no cost 

to the owner and should ascertain the cause of the 

excessive leakage. The service personnel should 

instruct the owner not to use the unit until the oven has 

been brought into compliance. 
• If the oven operates with the door open, the service 
personnel should: 
- Tell the user not to operate the oven. 
- Contact the manufacturer. 

• The service personnel should check all surface and 

vent openings for microwave leakage. 

• Check for microwave leakage after every servicing. The 

power density of the microwave radiation leakage 

emitted by the microwave oven should not exceed 

5 mW/cm

2

. Always start measuring of an unknown field 

to assure safety for operating personnel from radiation 

leakage. 

 

• TESTER(VOLTS-DC, AC., Ohmmeter) 

• Microwave survey meter 

- Holaday HI-1710(A) 

- Narda 8100 

8200 

• Inch scale 

• 600 cc non conductive material beaker (glass or 

plastic), inside diameter: approx. 8.5 cm(3

1/2 

in.) 

• Cylindrical and made of borosilicate glass vessel. 

max. thickness: 3 mm 

outside diameter: approx. 190mm 

height: approx. 90mm 

• Glass thermometer: 100°C or 212°F (1 deg scale) 

 

 

 

• When you replace the magnetron, measure for 

microwave energy leakage before the outer case is 

installed and after all necessary components are 

replaced or adjusted. 

Special care should be taken in measuring the 

following parts. 

- Around the magnetron 

- The 

waveguide 

 

 

 

 

 

 

 

 

• After all components, including the outer case, are fully 

assembled, measure for microwave energy leakage 

around the door viewing window, the exhaust opening, 

and air inlet openings. 

• Microwave energy leakage must not exceed the values 

prescribed below. 
NOTE: Leakage with the outer case removed less than 

3 mW/cm

2

. Leakage for a fully assembled 

oven (Before the latch switch (primary) is 

interrupted) with the door in a slightly opened 

position-less than 1 mW/cm

2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

• Do not exceed meter full scale deflection. 

• The test probe must be removed no faster than 

1 inch/sec (2.5 cm/sec)

 

along the shaded area, 

otherwise a false reading may result. 

• The test probe must be held with the grip portion of 

the 

handle. 

A false reading may result if the operator's hand is 

between the handle and the probe. 

• When testing near a corner of the door, keep the 

probe 

perpendicular to the surface making sure the probe 

horizontally along the oven surface, this may possibly 

cause probe damage. 

• After adjustment and repair of any microwave energy 

interruption or microwave energy blocking device, 

record the measured values for future reference. Also 

enter the information on the service invoice. 

• The microwave energy leakage should not be more 

than 1.0 mW/cm

2

. after determining that all parts are in 

good condition, functioning properly and genuine 

replacement parts which are listed in this manual have 

been used. 

• At least once a year, have the electromagnetic energy 

leakage monitor checked for calibration by its 

 

 

 

 

• Microwave power output measurement is made with 

the microwave oven supplied at its rated voltage and 

operated at its maximum microwave power setting with 

a load of (1000±5) g of potable water. 

• The water is contained in a cylindrical borosilicate glass 

vessel having a maximum material thickness of 3 mm 

and an outside diameter of approximately 190mm. 

• The oven and the empty vessel are at ambient 

temperature prior to the start of the test. 

• The initial temperature (T1) of the water is (10±2)°C It 

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 

turntable which is in the lowest position and the 

microwave power switched on. 

• The time T for the temperature of the water to rise by a 

value . T of (10±2)°K is measured, where T is the time 

in seconds and .T is the temperature rise. The initial 

and final water temperatures are selected so that the 

maximum difference between the final water 

temperature and the ambient temperature is

 

2°K. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

• The microwave power output P in watts is 

calculated 

approximately from the following formula : 

P=4187 x (△T)/T 

is measured while the microwave generator is 

operating at full power. Magnetron filament heat-up 

time is not included. (about 3 sec) 

• The water is stirred to equalize temperature 

throughout 

the vessel, prior to measuring the final water 

temperature. 

• Stirring devices and measuring instruments are 

selected in order to minimize addition or removal of 

heat. 

 

 

Before overhauling a microwave oven, you should judge the breakdown and the cause correctly, then you can repair it with 
corresponding ways. The overhauling must be proceed in order, any hasty conclusion is not recommendable, otherwise 
overworking would be done when repair. The microwave oven may occur compound breakdown due to all kinds of different 
reasons, thus, when overhaul, they all should be taken into consideration. Special attention must be given to the microwave 
leakage and the electric insulation when examine because they may do harmful to the repairing staff. 
Ⅰ

      How to examine a microwave oven with breakdown? A better means which demonstrated in practical operating are through 
inspecting and listening. On the basis of large amounts of perceptual knowledge, you can judge and analysis the breakdown 
quickly and correctly. 
1. Inspection. 

Inspect whether the oven shape is disordered and where is the disordered position, if any. It is normal if the outer case 
disordered a little, but abnormal if the oven, the door disordered, the door hook broken, the door crooked, or there are too 
much looseness between the door and the oven after the door is closed. 

2. Listening. 

Listening to the voice of the oven operating and the noise of the fan after it conducted. Minor “wen wen” noise, cycling “kala” 
noise and “shishi” noise should be consider as normal. But it is abnormal if the following noise occurred: 

(1)  Sound “wenwen” noise. 
(2)  Long time “shishi” noise. 
(3)  Strike voice like “pipa pipa”. 

Ⅱ

1.  Examine the microwave insulating resistance. 

Measure the insulating resistance with a multi meter or a mega ohmmeter. The value should not less than 2 mega ohm. 
Otherwise, part examination should be taken at once. Such as checking whether the motor, the thermal cutout, the 
transformer or the capacitor are electricity leaking. 

2.  Examination of the resistance value of the microwave oven. 

Close the door, set the time (the oven is at operating condition but the power plug haven’t been plugged in), measure the two 
feet(L-N)of the power plug with Rx1 grade of a multimeter, the resistance value should be about 22 ohm. 
If open circuit occurred, then you must check whether the

 

10 A fuse is broken、the primary winding of the transformer is open 

circuit、the thermal cutout is open circuit or not, you must check whether the interlock device is put through or all the plugs 

are connected well. If short circuit occurred, you should check whether the primary winding of the power transformer is short-
circuited or part short-circuited. 

3.  Examination of microwave leakage 

Measure the microwave leakage with a microwave leakage Measure. Place a graduate of 275ml water at the middle of the 
glass tray of the oven (FIG.5-1). Close the door, power set high, time set to 3 minutes, press the starting button to operate the 
oven. After rectified the microwave leakage measure, measure around the door crack, those hole position of the window and 
the air vent at four sides of the oven with the probe of the measure. When measure, the moving speed of the probe should 
not exceed 2.5cm per second, and the measuring direction should be the same with the outing direction of the microwave 
leakage (FIG.5-2). 
When measuring, the ultimate value of microwave leakage of all the measured position should not exceed 1.0 mili watt/cm

2

, 

or should be considered as abnormal. 

 

 

 

 

         

                                                                                                 

 

 

 

 

 

 

 

 

 

 

275ml

 

FIG.5-1 

Glass tray 

FIG.5-2