From: roger@hayter.org   
      
   On 30 Jan 2024 at 20:45:23 GMT, "Mike H"  wrote:   
      
   > I am trying to repair my Milwaukee M18 vacuum; model 0880-20. I left it   
   > outside, it rained, and the rest is history.   
   >   
   > I have only a very rudimentary knowledge of electronics from building   
   > Heathkits 45 years ago. That being said I am not afraid...   
   >   
   > Using my multi-meter as a continuity tester, I discovered a transistor that   
   > got rusty from the rain and does not appear to be functioning.   
   >   
   > Can't seem to post a photo but it has 3 lines of text:   
   >   
   > IRF1404   
   >   
   > IOR P446D   
   >   
   > TONH   
   >   
   > Google search has not yielded any results. I do not have a schematic. The vac   
   > is powered by a 18V lithium battery.   
   >   
   > In my testing I discovered if I connect a jumper between the left prong and   
   > the center prong, the vacuum seems to operate normally. If that is safe to   
   do,   
   > I am happy to just solder a piece of wire between those prongs and call it a   
   > day..   
   >   
   > Mike   
      
   The transistor may be defective, or just lacking a signal on the gate to turn   
   it on. Mosfets tend to be high resistance between all pins when tested in   
   pairs. It would not be a good idea to permenently bypass it as it could cause   
   damage to the motor, or battery if it has one. I suggest remove your short   
   circuit and see if a voltage appears between the source and gate pins (see the   
   datasheet others have drawn your attention to) when the vacuum is switched on.   
    If not, maybe the mosfet isn't the primary problem. FWIW, they usually fail   
   short circuit when the do fail, but then rusting is an unusual failure mode.   
      
   --   
   Roger Hayter   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)