ISO: Service info for an ADDS Envoy 580

[Josh Dersch]

Got me an ADDS Envoy 580 (at least, I'm pretty sure it is -- it has no
model designation apart from "Envoy" but looks identical to Jim's pictures
at http://jimsoldtoys.blogspot.com/2016/05/adds-envoy-portable-terminal.html
).

It's non-functional at the moment so it's going to need some repairs, and I
can't find much on it -- anyone have anything?

Thanks,
Josh