Re: diode check

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steven Ward by way of Terry Fritz <twftesla-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>

WOW,  my "good" diode was bad!!!  I put in on my VTTC and was getting some 
rather nice sparks, then i saw some smoke!  The diode case cracked open and 
sprayed liquid metal all over the near by resistors and caps! I guess i 
should be lucky that it didnt turn into a firecracker with plastic 
splinters.  Time to get new diodes ;)

Steve Ward.


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: diode check
>Date: Mon, 26 Aug 2002 00:04:49 -0600
>

>
> > Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>"
><jimlux-at-earthlink-dot-net>
> >
> > You'll need some sort of higher voltage supply to check the diode than 
>the
> > volt or so the VOM uses.  Something around 20-24 V should do.. Hook the 
>20
>V
> > in series with a 1 K resistor (or 470 or something..) that will limit 
>the
> > current to around 20 mA.  Now try the diode in both orientations.. A
>simple
> > VOM across the resistor will work..  zero volts means no current flow..
> >
> > In one orientation, you'll get some current flow.. typically, these MOT
> > diodes have about 10 V forward voltage drop, so you'll see the 
>difference
> > across the resistor.  In the opposite direction, you'll see no current.
> >
> > Bear in mind that the MOT diode is actually a bunch of lower voltage
>diodes
> > in series inside the encapsulation, and it is entirely possible that
>you've
> > blown up just one of them.  There are three possible situations facing
>you:
> >
> > 1) Totally fried and open.. no current either way
> > 2) Totally fried and shorted.. current both ways
> > 3) some diodes shorted.. current one way, but PIV and forward voltage 
>drop
> > reduced.
> >
> > if you have another (known good) diode of the same type to compare
>against,
> > it helps...
> > ----- Original Message -----
> > From: "Tesla list" <tesla-at-pupman-dot-com>
> > To: <tesla-at-pupman-dot-com>
> > Sent: Friday, August 23, 2002 9:53 PM
> > Subject: diode check
> >
> >
> > > Original poster: "Steven Ward by way of Terry Fritz
><twftesla-at-qwest-dot-net>"
> > <srward16-at-hotmail-dot-com>
> > >
> > >
> > > Hi,
> > >
> > > I was caught up in the moment and snagged the diode from my VTTC to 
>use
>it
> > > on a voltage multiplier.  Well the multiplier killed at least one of 
>my
> > > diodes(multiplier doesnt work), and i dont know which one.  I want to
>put
> > > the good one back on the tube coil but i dont know how to test the
>diodes.
> > > Does anyone know how?  I have a basic multimeter(VOM).  I think that
> > someone
> > > posted something awhile ago about this.  Oh, and its a microwave oven
> > diode.
> > >   Thanks
> > >
> > > Steve Ward
> > >
> > >
> > >
> >