# how do i test the sensors for a short



## tonesua (Jul 1, 2006)

how do i test the sensors with a meter to see if there is a short in my LPT2000 kit? I bought the one for to be able to have an overhead light source to count laps. 

I can get lap reading out of lanes 1 and 4. I bought it through Greg Braun, and my emails to him have not been returned. You can all chime in about buying trackmate (but my wallet wanted to do the work around, and I thought I had done enough homework with the search function on hobbytalk to justify the purchase.)


Should the sensors be powered up? (meaning, should I have the computer power on and port hooked up to the sensors)? I have it hooked up to a LPT1 printer port on a laptop running on old version of xp. I am running an AFX counter with a lightsource (2 15w bulbs) 

How close to the top of the track should the sensors sit? 


I would appreciate any help so I can do some racing with friends. We have some tycopros, pankcakes and non mags to cook and run.


Thanks


Tony in san diego


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## Franko (Mar 16, 2005)

technically it would probably be an "open" not a short. What kind of light source are you using? Using a multimeter measuring resistance you could make sure your connections are ok. Probably a problem with your pin connector to your computer, or your computer, or the settings in the software.


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## Franko (Mar 16, 2005)

I see you are usiing 15w visible light bubs. i use IR LEDs. They are more reliable for LED sensors.


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## Boosted-Z71 (Nov 26, 2007)

You can tell if it is a light source problem really quick by just holding a flash light above the sensor that is not working, and pass your hand under the light to see if it counts, I have had a couple that sensors that I had to replace as they just did not have enough sensitivity, even with IR leds as the source. I have had good luck with the Photo cells from Radio Shack Ask the clerk for RS Part No. 276-145 Photo-Transistor (4) & for the Light gantry or source use, 276-143 for the high output LEDs & part # 271-1115 for the 470 Ohm ½ watt resistors & you need a 12volt transformer.

Boosted


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## tonesua (Jul 1, 2006)

thanks to all. I actually resent my emails to Greg Braun and I have a response (check the trackmate" and "invert the logic", which I've done).

Our man in D.A.L.L.A.S TX uses a similar set up as mine and the sensors read the white light just fine.

I am going to pull out the sensors and check for continuity, broken ends, etc. 

I'll do the IR's as well if I can't get over this issue. I will be starting work again next week and have some hobby money funds rolling again soon so I can do it right. 

Do any you guys run tracks outdoors? Should I go to a different set up than IRs? Dead track is better suited for this, no?

Tony in S.D.


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## sidejobjon (Jun 3, 2010)

I was just having same problem. My fix was lining up sensors better and raising sensors.

Good luck worth a try
SJJ


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## alpink (Aug 22, 2010)

John, cool. glad you got it figured out and working betterer.


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## NTxSlotCars (May 27, 2008)

Hey Tony,

Check and make sure the sensor lenses are clear.
Sometimes the mounting method, be it hot glue, or chemical,
can haze the lenses. Also, try moving the light further away.
Sometimes a regular light can over saturate an IR sensor.
If you test with a flashlight, make sure its the old bulb style.
This is all assuming your components are working and program settings correct.

Outdoors, I would recommend deadstrips or reed switches.
Sunlight is too unpredictable, and can interfere with an IR setup.

Hope this helps.


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## tonesua (Jul 1, 2006)

NTxSlotCars said:


> Outdoors, I would recommend deadstrips or reed switches.
> Sunlight is too unpredictable, and can interfere with an IR setup.
> 
> Hope this helps.


I am going to test it later this week after a bus. trip up to the great NW (sea-tac, Everett areas)

I will report, and may have to move to deadstrips for a set up.

Thanks

Tony


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## tonesua (Jul 1, 2006)

*loks like it wasn't enough light*



tonesua said:


> I am going to test it later this week after a bus. trip up to the great NW (sea-tac, Everett areas)
> 
> I will report, and may have to move to deadstrips for a set up.
> 
> ...


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## Boosted-Z71 (Nov 26, 2007)

Brighter light, better focused & you may try rotating the sensors 90 degrees to how they are mounted now, Its not supposed to matter, but I had one photo cell that it read better when rotated in one direction versus the other.

Boosted


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## tonesua (Jul 1, 2006)

*most diagrams for the sensors show them*

Most diagrams I found for the sensor show that they aren't up that flush with the track, perhaps and 1/8th of inch below the hole that is made through the track. Does that sound right?


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## Boosted-Z71 (Nov 26, 2007)

I run mine with the dome flush to the track surface, although I did not drill all the way through the track either. only the dome top is visible on the cells I installed. I did something that makes them really easy to adjust, I mounted the photocells in a rubber stopper and drilled the bottom side of the table to fit the stopper. With the stopper installed you can still carefully slide the photocells up or down to whatever level you need and they are easily replaced since they are not glued in.

Boosted


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