I purchased this one used off of eBay sometime back. Exterior is pretty crusty, rubber handles have long broken off, and that
LIMITED sticker on the range control section led me to believe that something is amiss.
![Confused :-//](https://www.eevblog.com/forum/Smileys/default/confused0024.gif.pagespeed.ce.5xOqKkq0Co.gif)
Thanks to TiN for hosting a copy of the
Instruction Manual on xDevs.
Images follow, but first: does anyone know what the differences between the 193 and 193A models are? I did a quick search online and saw that the listed stability specs for the 193A seem to be significantly better, even though the two models appear to be functionally identical. If anyone has information, please post!
Full resolution album here.
![](http://i.imgur.com/by297cVh.jpg)
When I saw the back, I assumed that neither the ACV nor current measurement options were installed...
![](http://i.imgur.com/1yKfc3Hh.jpg)
Surprise! They're both installed. Digital section somewhat reminds me of that of the 196.
![](http://i.imgur.com/S7uDJpbh.jpg)
Back side.
![](http://i.imgur.com/Ftwe8jjh.jpg)
Model 1930 TrueRMS ACV Option
![](http://i.imgur.com/gxeJnFFh.jpg)
Model 1931 Current Option
![](http://i.imgur.com/Cpl3IwSh.jpg)
![](http://i.imgur.com/raX7DEHh.jpg)
That's actually black colored silastic underneath the capacitor.
![Huh? ???](https://www.eevblog.com/forum/Smileys/default/xhuh.gif.pagespeed.ic.6Nvt7O8a11.png)
![](http://i.imgur.com/crgudwlh.jpg)
30+ year old NiCd battery? Not confidence inspiring.
![ThumbsDown :--](https://www.eevblog.com/forum/Smileys/default/icon_thumbsdown.gif.pagespeed.ce.D027Y9gZ7m.gif)
![](http://i.imgur.com/ZC48lLAh.jpg)
This GPIB controller looks to have been replaced at some point. Date code doesn't match surrounding components either.
![](http://i.imgur.com/MuQ3lQSh.jpg)
Nice soldering job.
![Cool 8)](https://www.eevblog.com/forum/Smileys/default/xcool.gif.pagespeed.ic.cOxV6sPNRd.png)
![](http://i.imgur.com/9UwRbUSh.jpg)
Peering down into the great divide. I guess opto-isolators weren't prevalent back then.
![](http://i.imgur.com/ZmPhjiFh.jpg)
Analog section. Shield is held (firmly) in place by four metal clips. I see resistor networks everywhere, hope they're built to last.
![](http://i.imgur.com/FleIyfKh.jpg)
Classic LM399.
![](http://i.imgur.com/wKfSYdZh.jpg)
Two Caddock networks.
![](http://i.imgur.com/kzc2mv1h.jpg)
![](http://i.imgur.com/sPBixXPh.jpg)
I like the look of these Potter & Brumfield relays.
![](http://i.imgur.com/OP8PEARh.jpg)
Some quick sanity checks using an U8001A power supply. I dislike the auto-ranging behavior for DCV: if no input is connected, it will start rapidly cycling the relay (2-3 times per sec) to no end. I don't know whether or not this is normal, but it seems like an unnecessary burden on the relay's lifespan.
![](http://i.imgur.com/dcb3ZP1h.jpg)
![](http://i.imgur.com/OFq6e1Fh.jpg)
![](http://i.imgur.com/ypGFlaah.jpg)
Pardon the crappy camera work, hope you enjoyed it!