Spare a thought for the humble in-circuit test (ICT) fixture. Commonly referred to as a “bed-of-nails” these contraptions do things that we humans couldn’t possibly manage on our own. They maintain connections to many points of a circuit board simultaneously so that we don’t have to hold test probes with our hands and try in vain to look at a multimeter display and record a measurement at the same time. This perfectly trained platoon of pogo pins marches to the front lines of the circuits they test without regard for the dangerous voltages they may face. Shorting a cap may cause a deafening explosion and dousing in electrolyte, but they march on undeterred.
The fixtures are made at a time of great optimism and promise in the project timeline and they are happily working-class, costing only hundreds of dollars, while so many other tools command signoff from the finance department to buy. Since they are bulky and often iterated upon, ICT fixtures tend to be made by small local shops. To have a good “fixture guy” is seen as a measure of local knowledge and practical experience for hardware engineers. But each ICT fixture is doomed to be forgotten, draped in a uniform of stretch wrap, and consigned to the fixture cage until years later when someone finally puts their foot down and declares it scrap. This is because the fixture was a one-trick pony. As soon as the circuit board design is revised and the test points have moved to other locations, the pogo pins are in the wrong pattern for they are trapped in the past like a small insect in a chunk of amber or a key to a lost lock.
At Blue Clover Devices we have reimagined the ICT fixture to give it new life: bcdevices.com/ict