RE: Kill-A-Watt Meters - What's in there?

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

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi,

Perhaps that is why they stress 125VAC Max. in the instructions.  Maybe 
they got some back that had been blown up ;-))

I note that there have be a few revisions since there are minor differences 
in the cases and printing.  They may have tried to improve them since...

Of course, the best way to find out is to pull the three little case screws 
and see what's in there ;-))  It comes apart and goes back together easily

http://hot-streamer-dot-com/temp/Kill-A-Watt/P3120005.jpg

http://hot-streamer-dot-com/temp/Kill-A-Watt/P3120006.JPG

I left these pics big to see small detail.

The guts happily float at AC but are well isolated.  I am surprised they 
use a PCB trace to connect the ground (maybe that is why it does not carry 
CE!  May also make it hard to fine in the EU areas).  They have a 0.47uF 
cap across the line with a 200 mA fuse(!).  It would not take much of a 
spike to blow it.  Bet that is what goes bad.  This is just plain VI pick 
off stuff.  A little 5 volt supply circuit and other expected stuff.  No 
adjustments!  I'll guess it is digitally caled at the factory.

The magic chip is a:

PRODIGIT
53920005
11207A  J213

A 4.194304 crystal (could use a bit of glue to hold it in 
place).  Soldering around the AC connections is pretty weak.

So, if one dies, I would suspect the fuse or solder connection on the AC 
terminals (don't beat on the fragile plugs).  Try not to pump too many 
kAmps though the ground!!  That little ground trace will evaporate easily.

I would not add internal MOVs since the PC traces and all could not take a 
serious event.  But it looks like the fuse probably does a pretty good 
job.  External MOVs would stop high voltage spikes but probably not prevent 
the fuse from blowing.  It looks fine the way it is.  Just might need a new 
fuse and a soldering check now and then.

Cheers,

         Terry

At 01:40 PM 3/12/2003 -0500, you wrote:


>I was using (2) 20A corcom filters (in parallel) between my controller and
>the wall outlet with the meter.
>Still, didn't seem to help much.
>
>Dan
>
>
>
>Perhaps these meters should only be used with a corcom filter between it and
>the TC?
>
>-Pete Lawrence.
>
>
>  >Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><dhmccauley-at-spacecatlighting-dot-com>
>  >
>  >All,
>  >
>  >I bought a P4400 Kill-A-Watt meter last year for use with my SSTC coil.
>  >However, on initial running of my SSTC, the unit was very quickly killed.
>  >
>  >These things appear in my experience not to be built too well for tesla
>use.
>  >Perhaps others have had better luck????
>  >
>  >The Captain
>  >
>  >