Future Retro Swynx - Manual (Page 9)

PHONE JACK
The phone jack is a stereo output. The Tip connection will provide
Analog Clock or CR-78 clock signals. The Ring connection will provide
an Analog Reset signal, or the CR-78 Write signal.
If only the clock signal is needed, a mono cable can be used with this
output.
If your situation requires Clock and the Analog Reset or CR-78 Write
signals, use a “send-return” audio cable to break the stereo signal out
into two separate mono signal connections. These cables are available
from most music stores, and the mono signal connectors are often
labeled as either Tip or Ring for clarity.
LED
The LED on the front panel will blink to indicate activity of the Analog
Clock or CR-78 clock, which ever is selected.