Yep if the customer can't tell, it's ChaBuDuo! That's part of the reason there's so many damn tests in production and it's so damn hard to ever get rid of one.

Yep if the customer can't tell, it's ChaBuDuo! That's part of the reason there's so many damn tests in production and it's so damn hard to ever get rid of one. One of the first and trickiest I had to deal with was a black paint. You can get the black in paint from a lot of different sources, but some of them are (slightly) conductive. The paint had been specified, but when margins are tight the way a CM makes extra money is sourcing on the down low. Well, that conductive paint made things not work! The solution was to measure the conductivity, but there were millions of panels already made up and so a non-contact jig had to be made and a new test added to (near the beginning of) the assembly line to detect and separate the bad parts. It turned out that even after the initial paint substitution, the paint supplier changed their own process and this jig became useful again. It a significant piece of IP that made out product more reliable than others! It was made in the US and shipped to Asia (where I'm sure the reverse engineered it).