Hello TEAMS,

We have been made aware of an issue with one of the Gear Tooth Sensor boards in the sensor array strip from the kit of parts. R3 and R4 as noted are swapped. After some evaluation it was found the original Bill of Materials we were given to build from had the placements incorrect on one board. After we got ahold of the schematic, the switch was confirmed. All is well now from a systems end, but we must help out you teams. If any of you feel comfortable making the swap, then have a go at it. For the rest of you who do not, we will swap the two resistors for free.

To have your board repaired, please send the board to Diversified Systems, Inc, Attn: Ben Wrightsman, 3939 West 56th St., Indianapolis, IN, 46254. For questions, you can contact me directly at 317-299-9547 x350. We, the diversified systems, inc. crew will repair the board and return it to you promptly. Again, if you have the resources, skill sets,and are comfortable making the repair yourself, you’re more than welcome to do so.

***NOTE, only one of the two gear tooth boards has this issue. Picture attached. If you look at the resistors under magnification the correct R4 should read “1001” and R3 should be “1004” The board with J4/J5 is the only incorrect board ***

One question I would like to ask, what team caught this issue? If I can get reply with their name, Team#, and contact we will send them a special gift. You caught something that two large companies have missed for 2 years until now. We want to reward you for that feat.

thank you,
BMW from dsi

Schematic http://www.usfirst.org/uploadedFiles/Community/FRC/FRC_Documents_and_Updates/2008_Assets/Manual/Sensor%20Strip%20Schematic.pdf

This is fantastic support for the teams - thank you very much!

I believe that the error was initially tracked down and verified by Team 1726. See this thread for the original discussion of their description of the problem and recommended solution.



what about israeli teams?

The funny thing is that I’m a mechanical engineer


Team 604 was onto the problem at the same time…

Wait, does this mean EVERYONE’s kits have at least one Broken Geartooth Board or does this mean only Half of them are broken?

And anyone have suggestions on how to check if they are working properly or not?

We checked ours by installing them in the transmissions and driving the motors and watching the input on the laptop…but you could just screw them onto the transmission side plate and then put the gear, shaft and bearing in place, and spin it by hand and watch for a signal with an oscilloscope

Apparently ALL of the sensor board sets were made with the outboard GTS board having the resistors R3 and R4 switched. This includes 2007 and 2008 sensor boards! This is according to Ben from DSI, we just talked on the phone. Hopefully he’ll correct me if I’m wrong.

Um, I have a small Electrical problem… when you look at the Schematic


It shows what is supposed to be what. When I measure their resistance, R4 is supposed to be 1K ohm, but on one of the boards it says .350K ohms, and on the other one it say it is .450K ohms. So what the hell is going on?

Also, one R3 is 1M Ohm Resistance, while another R3 is only 1k Ohm.

For some reason our boards seem to be messed up beyond belief, or am I just freaking out?

Look at the markings on the resistors, you’ll need a strong magnifying glass, or take a digital high resolution picture.

The resistor markings are 4 digits, the way they work is that the first 3 digits are the value, and the last digit is the multiplier. So the resistor marked 1001 means 100 x 10^1 or 1000 ohms or 1 K ohm. The resistor marked 1004 is 100 x 10^4 or 1,000,000 ohms or 1 M ohm

Usually if you are trying to measure the resistance of a resistor (especially a 1 M ohm resistor) while it is in the circuit, you will get a much lower resistance reading because of the other components connected to it.

This thread

has some close up pictures of the boards, you can almost read the resistor values.

Nice job on uncovering the problem with the sensor, squirrel. Our team got 1 good one and 1 bad one as well. We would send in the bad one to be fixed, but we already threw it out. :confused: Due to time constrants, we went with the Honeywell sensors that work prefectly.

Thanks for offering to fix them all divsys, that is fantastic support. :smiley:

Thanks for the help Squirrel. Much appreciated.

I thought you had corrected your original post yesterday, so I removed mine. Now it looks like the same discrepancy is back.
If you read this post, you will see that the team that found this issue is stating the other board is the one with issues. The one with J4/5 is good and the one with J1/2 is bad.

So, who is correct?

I recall that the board on the end of the strip J1 J2 was bad, and the other one was good. But looking at the schematics, and the boards, it appears that the J4 J5 board is bad!

I cannot test the boards right now, hopefully someone else who has switched the resistors on one of the boards and now has two working sensors can verify which one is wrong.

As far as I can tell, the GTS board with J4 and J5 is indeed the one that needs to be repaired. I visited my brother today and he swapped the resistors, and explained the circuit to me first…

also before I went to see him, I connected each sensor board to a power supply and oscilloscope, and chucked up a small steel gear in a drill and tested them both, and the J4 J5 board did not seem to be working, the other one did put out a signal.

So it looks like I misidentified the problem board in the other thread, sorry for any confusion!

Thanks for the clarification Jim. Your efforts are appreciated.

On a side note, we decided to use Honeywell GTS’s this year instead of the KOP sensors.

My post and information is correct as stated.

The second board in from the end is incorrect. The end board is correct, per the schematic.

I want to thank you for your follow through. As mentioned above, Jim also verified you were correct.
I also want to thank you for your decision to make these boards available in the first place and to repair them for any team that would like that service.
Personally, I hope you will be providing these sensors next year and in the future! All four of these sensors are well designed and well worth using.

im not 100percent on this so dont hold me to it but i think ares works.