RaceAmerica Online Forum

What's the difference between the tri-beam for the 2800 and the tri-beam for the 2900? They look pretty much the same from the outside and the functions each beam serves must be the same.

Yes, the beams function the same but there is an internal electrical difference and a difference in the way a tri-beam start line beam connects to the timer. The physical hole size for the beams on the sensors are different with the current tri-beam having 0.1in hole and the older sensor has 0.4in.

The internal electrical difference is there are three unique beams in a tri-beam so they do not interfere with each other. The unique beams in a tri-beam made for a 2800 system are different from the 2900 model with the prestage beam not compatible with each other. Guard and stage beams are the same in both tri-beam models. This applies to both the tri-beam emitter and the tri-beam sensors units.

The timer connection difference is the how the tri-beam sensors physically connect to the timer. The older 2800 compatible model has three signal outputs to the timer and the timer logically compares the status of the guard beam with the status of the stage beam. The current 2900 compatible model has two output signals. This tri-beam has an internal circuit board connected to the guard and the stage beams and handles the status comparison, then outputs the result along with the prestage beam to the timer.

If you connect an older tri-beam sensor/emitter set to a 2900, the timer will receive the beam status of the prestage and stage beams only and the guard beam would not be connected to the 2900.

If you connect a current tri-beam sensor to the 2900 and pair it with an older tri-beam emitter or visa versa, connect an older tri-beam sensor and pair it with a current tri-beam emitter, the prestage beam is uniquely different and will never align.

Connecting a 2900 compatible tri-beam sensor to the 2800 timer will result in only two signals sent to the timer. The timer would not receive the guard beam resulting in the guard beam appearring to always out of alignment and the internal logic board of the current tri-beam sensor would assume a vehicle has pulled too far forward into the guard beam and would not allow the stage beam to function.

Can a 2800 style tri-beam be reworked into a 2900 tri-beam? If so, what needs to be done? I have a set with our old timer and are planning on moving to a new wireless system and it would be nice to use what we have.

BillGorman wrote:Can a 2800 style tri-beam be reworked into a 2900 tri-beam?

Yes, they can be upgraded. The prestage beam sensor would be modified and re-tuned depending on the age of the unit, else the prestage beam sensor circuitry would be replaced. The sensor enclosure would be updated with the smaller openings for improved range. The stage and guard beams would be tuned and aligned for the new beam openings. and finally, the stage/guard logic board would be added with a different wiring harness.

A little involved on our end but it upgrades the older hardware at a lower cost than buying new and can be reused with a newer timer.