Maytag 1800 W - 2005 Manual De Usuario

To avoid risk of electrical shock, personal injury, or death, disconnect power to oven and discharge capacitor  
before servicing, unless testing requires power. 

©2006 Maytag Services

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A magnetron tube, like a radio or television tube 
must be handled with a reasonable amount of care. 
When handling a tube, always handle by the housing 
only. Use caution not to touch or strike the ceramic 
portion at the top. The carton used to ship service 
replacement tubes is reusable. 

 

Magnetron failures that have been identified are 
generally grouped into categories shown below. 

1.  Shorted 
Air - This is a case where the tube has had the vacuum 

envelope destroyed and air has entered the tube. 
This will cause internal arcing and high secondary 
current if high voltage is applied. 

 
R.F. Capacitors - May short to chassis. This condition 

will also cause loss of high voltage. 

 

2.  Open Heater (Filament) - Can be determined by a 

ohmmeter when transformer leads are 
disconnected. Resistance is normally less than one 
ohm; filament does not short internally. Any tube 
removed should be checked since usage tends to 
make the filament more fragile. Later handling and 
shipping may open the filament and thereby mask 
the true failure mode when checked at the factory. 

3.  Low Power - Caused by “wearout” of the emission 

characteristics of the directly heated cathode. 
Symptoms are: (1) tube current will take longer to 
get to operating point than a new tube (normally 
about 2 - 3 seconds), (2) tube current does not get 
high enough to cause the tube to oscillate with 
normal line voltage, (3) oven produces low power 
into a load, two-thirds or less than normal. 

4.  Physical Damage - Caused by mishandling of 

magnetron tube.