Time Machine | Chronomix Interface
This guide details how to connect the Time Machine to a Chronomix display clock, including wiring instructions for the various required cables and adapters.
Synchronize a Chronomix Display
- Connect a standard telephone cord to the EXT CLOCK port of the Time Machine.
- Connect the other end of the telephone cord to the adapter (see wiring instructions below).
- Connect the adapter to the FinishLynx to Chronomix cable.
- Connect the cable to the DATA port on the Chronomix display clock.
- Once connected, power on the Chronomix clock and the Time Machine. Start the event. The Chronomix will display the running time from the Time Machine.
Known Display Quirks
Initial Digit Display: Upon starting the Time Machine, newer Chronomix clocks, including the 7300, may initially display incorrect time. Specifically, it may show a "4" in the 10's of minutes and another "4" in the 10's of seconds. Recent testing suggests this may not be a hardware design flaw in the Chronomix itself, but rather specific data being sent from the Time Machine that sets those initial digits. These digits remain until the Time Machine overwrites them (e.g., during a cross country meet, the time may look incorrect for the first 11 minutes). This occurs whether counting up or down.
Workarounds:
- 10-Hour Offset (Recommended): Set the Time Machine to start at 10 hours, 0 minutes, and 0 seconds (10:00:00). Because the Chronomix 7300 only has a 5-digit display, it will only show the rightmost 5 digits. Note: The downside is that instead of blank spaces for leading zeros, it will display zeros (e.g., nine seconds will display as "00009" instead of " 9").
- Physical Masking (Alternative): If you choose not to use the 10-hour offset, the incorrect "4" digit will display. However, for events under 11 minutes, you can simply cover up the errant number four by taping a piece of black paper or similar material over the 10's of minutes place on the display.
- Delayed Power-On (Alternative): For longer events without the 10-hour offset, keep the display off initially and turn on the Chronomix clock after 11 minutes have elapsed to bypass the incorrect digits entirely.
Continuous Counting: Newer clocks (like the 7300) will continue counting up even if disconnected from the Time Machine. This is useful: you can use the Time Machine to start the clock, disconnect, and move without worrying about cables. Older Chronomix models will stop if disconnected and must remain plugged in.
Building the Time Machine Adapter
This adapter allows the use of a previously created FinishLynx to Chronomix display cable.
Wiring Specs:
The green adapter has a DB9 (female) connector on one end and an RJ11 or RJ12 (female) connector on the other. It uses just two wires:
- Red Wire (Transmit): Connects between pin-2 on the DB9 and pin-3 on the RJ11.
- Yellow Wire (Ground): Connects between pin-5 on the DB9 and pin-1 on the RJ11.
Tip: The remaining wires are unused and could be snipped off. I used shrink tubing instead and tucked them away for possible future use.
The green adapter is connected to a male-to-male null modem adapter, which in turn connects to the DB9 (female) connector at the end of the FinishLynx to Chronomix cable.
Design Note: I had to make that cable adapter quickly with existing parts. If making another, I would use an adapter with a DB9 (male) connector to avoid needing the easily-misplaced null modem adapter.
Reference Gallery
Ext Clock Port
DATA Port
Display Time
Display Error
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