RotaryCell / build guide

Finish the board cables

The LilyGO harnesses and their lengths were covered while preparing the controller. This page completes the two cables that join the custom boards and the telephone. It assumes you already know how to strip wire and crimp the contacts correctly.

Wire colors are not part of the circuit

You do not need to copy my wire colors or follow the same overall color scheme. I used a combination of what I had available and what helped me keep the wiring straight. Use colors that let you distinguish conductors wherever polarity, connector orientation or signal identity matters, and record any substitutions you make.

Audio board to carrier

Use a 10 cm three-conductor cable between Audio A4 J2 and carrier U2. It is wired straight through, with blue outer conductors and black in the center.

Audio A4 J2	Carrier U2	Signal
Pin 1	Pin 1	VIN
Pin 2	Pin 2	GND
Pin 3	Pin 3	VOUT

Completed three-conductor audio-board-to-carrier cable

Carrier to telephone network

The two-position NETWORK connector on the carrier runs to the telephone's network block. Use green for tip and red for ring so the original telephone convention remains obvious during installation. Leave the network block ends untrimmed until the boards are in the phone.

Audio interconnect and red-and-green network cable

I use this crimp tool and connector kit for the harnesses. The kit also supplies the through-hole headers for the boards. Refer back to Add the LilyGO connections for the controller-side cable lengths and signal assignments.

Check both ends of the audio harness

Do not use the connector shells alone to judge wire order. Compare the signal at every position on the LilyGO end with the matching Audio/Reset A4 pin. A housing can plug in normally even when its conductors were inserted in reverse order.

Check the finished cable

Verify every conductor end-to-end and check for unintended connections between adjacent pins. Gently check that each contact is retained by its housing.

Connector names repeat

Audio A4 U2 is the reset connector. Carrier U2 is the audio connector. Always include the board name when checking a connection.