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Carrera Laptimer

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Carrera Lap timer #71590 conversion


I will try to describe how I reworked my Carrera Lap timer part #71590, to run with an old phone charger instead of the 4 AA batteries.


The very first step if you want to try this should be to check the output of the phone charger, because the one I wanted to use said its output is 5.7 Volt, but it was actually 8.7 Volt. Since I did not do this at the start, this should be a “learn from your mistakes†tip.

Also decide now on what side you need the connector to be, depending how your track is laid out.


Now I took the display apart, which is held together with the yellow screws, there are 3 Philips head and 1 T10 Torx screw.

Not sure if all lap timers will have the Torx screw, but mine has it.

Second were the red screws on both sides, the bottom one is only visible, once the battery cover is removed.


<a href="http://s49.photobucket.com/albums/f267/pitlane324/?action=view¤t=lt1.jpg" target="_blank"><img src="http://i49.photobucket.com/albums/f267/pitlane324/lt1.jpg" border="0" alt="lt 1"></a>


Once the covers are apart, I cut the blue and red wires on one side of the lap timer, cut the isolation back, twirl the bare wire, place some heat shrink over one cable, and solder the 2 cables together.

As I have no heat gun for the heat shrink, I just run the soldering iron a few times over it.




Then it is to the other side, drill the hole(s), where you want your connector to be, I checked the fitment, before I cut the wires, add the heat shrink over the bare wires and soldered them to the connector. Please make sure you have checked the polarity of your phone charger beforehand.




Once you have all wires heat shrinked, and your connector mounted to the lap timer, you are ready to reassemble it.

My Laptimer does everthing it did before, but without loss of power.

It will still switch itself off after 3 minutes if there is no signal (car) going through.

And now it’s time to do laps without the batteries stoping the race.

Enjoy. :rolleyes:


Pitlane 3


PS: By carrying this work out, you will lose your warrenty on the laptimer.

Edited by pitlane3

"If one does not fail at times,

then one has not challenged himself."


Ferdinand Porsche

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