Notes on the 4-wire Connecting Cables and Jacks

The cables are standard 4-wire telephone cables. If you turn one of these cables around nose-to-nose, the individual wires will align with their opposite end, and it follows that the left-to-right pin ordering for two jacks connected to each other, will be mutually reversed. The pin ordering at the V1, for example, is the reverse of the pin ordering at the jack to which it is connected. Hence, each jack is either “type-A” or “type-B”, and any jack may only be connected to a jack of the complimentary type. In order for the pin ordering at the V1 to be the same whether it is connected directly to the power adapter or via the Remote Audio Adapter (RAA), the pin ordering at the RAA’s power-out jack must be the reverse of the pin ordering at its power-in jack.

The correct pin ordering must be obeyed at any jack, but otherwise and except for the ability of the RAA to control power to the component daisy-chained through it, any configuration will work. The two center-most pins are power and ground, so if the pin ordering is wrong at any jack, one effect will be to reverse the polarity of the power connection. One of the two remaining pins carries data from the V1 to the two accessory modules, and the other remaining pin carries +5V, which provides power to the RAA and additionally allows either of the accessory modules to signal to the V1 that the mute has been engaged, by momentarily connecting that line to ground (via an appropriate resistor).

The type-A jacks are:
  • V1’s jack
  • RAA’s power-in jack
  • The accessory-out jack on the direct power adapter and the newer cigarette lighter adapter (the original cigarette lighter power adapter does not have an accessory-out jack).
The type-B jacks are:
  • Concealed Display’s jack
  • RAA’s power-out jack
  • Main/V1 jacks on the power adapters
For example, the RAA’s power-out jack can be connected to the accessory-out jack on the power adapter, in which case the Concealed Display (CD) can be connected to the RAA’s power-in jack, thereby permitting the RAA to control power to the CD.

By using a T-adapter, it is possible to increase the number of jacks of the type to which the base/prong of the T-adapter is connected. The prong of a regular telephone T-adapter can be inserted directly into one of the component jacks (or into one end of an in-line coupler, with a length of cable used to connect the coupler to one of the component jacks). It is thus possible, when using the single-jack cigarette lighter adapter, to connect all three components. Because the CD has to be connected to a type-A jack, the base of the T-adapter can be connected at either the RAA’s power-in jack or the V1’s jack, and if the V1’s jack is used, it is possible to use the CD with the single-jack cigarette lighter adapter but without the RAA.

Note also that since the two side-by-side jacks on a T-adapter share the same pin ordering, a T-adapter can be used to convert any jack to the other type. For example, if the CD is connected to one of the two side-by-side jacks on a T-adapter, that jack will then be a type-A jack, and the same goes for the jack next to it. For that matter, a non-conformal cable can easily be made, simply by installing the connector the wrong way. However, when faced with the need to interconnect an odd number of jacks, the only solution, other than ordering a component that you don’t need, is to use a T-adapter in the manner intended.