On Electrical Connectors

By ARNO HOLSCHUH 

In the world of negative workplace emotional experiences, few compare to buttoning up a job and ruining it by breaking an electrical connector. It takes a second for your brain to understand that a tiny little plastic connector has crumbled between your fingertips, the machine is not running without it, and the closest spare part is in another time zone.

Those tiny little connectors are vastly important to today’s brewing equipment. We’re going to take a short look at where they came from, why they are so important in modern equipment, why they are sometimes delicate, and how you can fix (some of) them in the field.

Electrical connections on older machines were primarily executed at terminal blocks, and you still see a lot of that today. These are rows of connections, where you put a wire into one side, screw it down, and then put another wire in the other side and screw that one into place too. They’re nice because they are very robust, although the plastic insulation used can become brittle with age and exposure to heat. That’s kind of a theme here -- brittle plastic causes a lot of problems.

The problem is, machines are getting smarter. The first volumetric machines used rows of little physical relays to execute their rudimentary logic; those you could still hook up with 12 or 14 gauge wire. But once machines started to incorporate printed circuit boards in the 70s and 80s, it became much more common to see connectorized wiring take the place of terminals. There was a lot more going on, especially for low-voltage logic applications like automatic fill sensors or flowmeters.

Luckily, the Molex corporation had invented a connector that perfectly fit the bill. They got the patent for a nylon-insulted connector that used spring-metal contacts to hold itself together in the 60s. By 1980, they were everywhere, thanks to the popularity of personal computers. And our industry took note.

You start to see a lot of little plastic connectors in espresso machines around this time. They have a male and female component, so you don’t end up hooking it up wrong. Many have little clips to secure the connection; many are used to connect “ribbon cables” made up of many, many low-voltage, very fine wires arranged into a “ribbon.”

And many, sad to say, have crumbled into dust. Nylon is tough, abrasion resistant, and above all heat resistant -- but even nylon will become very fragile with age and exposure to heat. If a connector was once white and is now yellow… beware.

What can a field service technician do? The first thing to understand is that you may not be able to fashion a fix, no matter how skilled you are. If the plastic housing on a 24-pin ribbon cable falls apart, you should probably go ahead and let the client know they’re not going to be making any more lattes that day. The very fine wires and delicate connections, and the potential to fry a more expensive component if you get it wrong, all counsel against heroic gestures.

If the connection is relatively simple and the wire is relatively thick -- we’re talking about 22-gauge or thicker -- you can use any of the commonly available solderless connection options used in cars. I’m a fan of the ScotchLok line from 3M, but there are a lot to choose from. One can purchase a Molex crimper and connector and try to manufacture the connector and cable on-site. Beware; Molex crimping is a test of manual dexterity on the same plane as surgery. It’s pretty easy to do it badly, very hard to do it right, and the consequences can be dire.

The best way to excel at electronic cable repair is to assess what models you work on most frequently, and add some pre-built cables from the manufacturers to your van stock. If you carry a spare brain, you ought to be carrying the cables that make it useful to the rest of the machine as well.