Viz WD-767 AC Watt Meter Teardown

[GAD]

A few weeks back I scored an old Vector Vid Variable Isolation Transformer and have subsequently fallen in love with it. That caused me to wonder what else was out there by the same company, which has been Viz/Vid/Vector/RCA/who-knows-what-else. That's when I found this: A Viz WD-767 AC Watt Meter.




They made two models, the 766A and the 767, which were 10A and 20A respectively. This is the 20A version which is rated to peak at 35A. It looked almost new in the auction ad, so I snagged it for what seemed like a reasonable price. Why? Because I have the disease, just like most of us. I love older well-built analog gear and this thing looks great sitting next to the ISO-V-AC-III, and it's even useful. Sure, A modern Kill-A-Watt will give me more info, but they don't peak to 35A!

Naturally, the first thing I did was tear it apart.




Not surprisingly, there's not much to it, and the big case with the little transformer made me chuckle a bit. It's almost as if they were trying to make the buyer believe there was more going on inside it than there was. But then, this is from the age when men were men and cases were made out of steel!

Overall it's well-made, though there are some rather interesting solder joints where there was just too much wire to fit into the lugs. I will say that those solder joints are rock-solid, so I'm resisting the urge to re-solder them.




Out of the box it was a volt or two off from all my other test gear, so after digging around online I found the manual which has the full schematics (man, I miss those days), and of course there are some pots for twiddlin' on the board. Since I have a tweaker and I'm not afraid to use it, I dug in.

The board is pretty simple, and I have to say that I just love old boards that don't have surface-mount components. I'm 51, and boards like this just seem "right", uncleaned rosin and all.




Of course, sometimes the engineers don't talk too closely to the fabrication guys. The thread marks in the pot are from one of the screws that holds on that steel case cover.




No real harm done, though, and the pot works as advertised, as do the other two. With some balancing and some testing, I got it agreeing with my Fluke in no time. Plugging a space heater into it and simultaneously measuring with an amp clamp also showed spot-on readings.




All in all I'm pretty happy with it. Is it worth the space it takes up on the bench? I dig it so the answer is "yes".