On Saturday, July 17, 2021 at 3:57:08 PM UTC-5, hon...@yahoo.com wrote:   
   > I have a microwave from the mid 2000s that failed on me. It uses basic   
   circuitry: transformer, diode, cap, magnetron....not an inverter type or   
   anything fancy like that. One morning it seemed to mostly work, but the output   
   rapidly dropped over a few    
   minutes. No bang, no smoke. Just stopped heating.    
   >    
   > Everything tests ok, the transformer, diode, cap, even the magnetron   
   resistance measurements are "good". I know there's about 10A to the filament   
   with indirect testing, and I know the capacitor has near 2kV on it right after   
   running the unit and    
   unplugging it. This was determined by knowing the cap has an internal bleeder   
   and using the RC time constant to allow the voltage to drop to a safe value to   
   measure.    
   >    
   > Would this be indicative of a bad magnetron? Almost everything I read about   
   magnetron troubleshooting leads me to believe there's nothing wrong with it,   
   but then again the rest of the circuit also seems to be functioning correctly.   
      
   So.....magnetron seems to have failed again, not quite 1.5 years later.   
   Microwave was running, then stopped heating. No bang, no smoke. I put my   
   wattmeter on it, tried cooking again, saw around 1.2kW usage for a few seconds   
   and thought it was ok, but    
   then dropped to around 300W. I haven't taken it apart yet but my bet is a bad   
   mag.   
      
   This was a genuine OEM replacement part from a reputable supplier. So either   
   1. the part was defective and prone to early failure from the start or 2.   
   something is making it fail early. But what? As I think about the other parts,   
   the transformer, diode    
   and capacitor, I can't come up with a way for those parts to cause early mag   
   failure. Transformers don't fail in a way that causes increased output voltage   
   (not that I've seen), and a bad diode or cap doesn't seem to be capable of   
   destroying the mag.   
      
   The original mag lasted 14 years and the usage has always been the same.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)