Connectors

Organs had complicated interior layouts that included various chassis and printed circuit boards connected by wiring harnesses. Even Wurlitzer’s less elaborate instruments, such as their electronic pianos, mounted potentiometers on panels that were inches or feet away from the electronic chassis. This gave the user easier access to the controls, but it required additional wiring.

Wiring harnesses add complexity to a circuit, and they have to be terminated in a way that is appropriate for the type of wire and the signal that it carries. The simplest way to terminate a wire is by soldering it directly to its terminal. For instance, the wire can enter a chassis through a hole and connect directly to its intended endpoint. This is acceptable as long as the wire has adequate strain relief. Power cables are often connected in this manner. Or, a wire might be wrapped around a post that is soldered directly to a PCB.

In cases where multiple wires must enter a chassis or mount to a PCB, a connector is used to organize the wires and help them lock into place. There are typically two halves to a connector. One half is mounted on a PCB or a chassis, and the other terminates the wiring harness. The two halves fit together, and some sort of release mechanism allows them to be connected and disconnected as needed.

Wurlitzer often used connectors by Molex. Molex connectors are usually composed of a plastic housing that holds individual metal contacts. One half of the housing contains the “male” contacts, and the other half contains the “female” contacts. When “mated”, the contacts lock together in a stable mechanical hold that can be manually disconnected either by gently prying them apart (in the case of a friction lock) or by squeezing a release tab (in the case of a latch mechanism).

The way that wires terminate contacts varies by connector design. An insulation-displacement connector, for instance, cuts the wire insulation and holds the conductor without requiring the wire to be stripped or soldered first. Other types of connectors require crimping or soldering the wire into place.

During the vacuum tube era, most connectors were octal or 11-pin socket-and-plug assemblies. Wires were inserted into hollow pins, and the connection was terminated by flooding the pins with solder. This system required a lot of chassis space, and, because it is not a true mechanical connection, it requires a fair amount of skill to adequately terminate. As electronic circuits became denser, new types of connectors were developed that were easier to terminate, featured crimped mechanical connectors, and occupied less space. For this reason, the connectors found in a circuit are very characteristic of the time period in which it was made.