Problems with IR Board

[Richard McClellan]

Originally Posted by Chris_Elston

1501 IR board works great out of the box.

Hmm....I don't quite understand how you are powering your IR board. Is the power coming from one of the IO ports on the Vex controller? The power output is only 5V, so does the IR board still work when the minimum required input voltage is 7V?

[billbo911]

Originally Posted by richardmcc2

Hmm....I don't quite understand how you are powering your IR board. Is the power coming from one of the IO ports on the Vex controller? The power output is only 5V, so does the IR board still work when the minimum required input voltage is 7V?

Vex controllers are quite similar to the FRC RC. The Vcc voltage out on the Analog in and Digital in/out connectors is +5vdc. The Vcc voltage on the PWM connectors is the same voltage as the backup battery on the RC and the main battery on Vex, both being +7.2vdc.

[sayso_411]

Hmmm... thats funny because our IR board worked at first try with a Toshiba TV remote (cant tell but probably something wrong with IR board)

[Richard McClellan]

Originally Posted by billbo911

Vex controllers are quite similar to the FRC RC. The Vcc voltage out on the Analog in and Digital in/out connectors is +5vdc. The Vcc voltage on the PWM connectors is the same voltage as the backup battery on the RC and the main battery on Vex, both being +7.2vdc.

Well that's good to know. I can't see exactly where the power is coming from by looking at the picture. It really still looks like they're coming from the Analog/Digital IO ports, but I guess they could be from the motor ports.

Chris_Elston, where are the power leads connected?

[Chris_Elston]

Originally Posted by richardmcc2

Chris_Elston, where are the power leads connected?

I had the power on the PWM servo power 7.2 volts on the VEX as spec'd, but then I decided to try it on the I/O side as you see in the pictures. There is only 5V on that side of the VEX controller. So the IR board works at 5volts....dog gone it...the cat's out of the bag....I didn't move the wires when I took the picture....

I have logged in feet the signal degrading factor using 5 volts, verses 7.2 volts. It's about 0.37 times factor.

[Wendy Holladay]

does anyone know how to get a board, ours got lost, can you buy them, should i call first or ifi?? any help would be get

wendy holladay
mentor team 1912

[keen101]

Originally Posted by whollada

does anyone know how to get a board, ours got lost, can you buy them, should i call first or ifi?? any help would be get

wendy holladay
mentor team 1912

I'm not sure. I'd like to get a backup one as well.

I may have to start emailing diversified systems, as IFI does not seem to carry them.

[Phalanx]

We had a burning smell and got no response. We used a 9V battery.
We confirmed and doubled checked that the wiring was done correctly.
I did the wiring myself and had it doubled check by another Mentor.

We did find the the voltage regulator was lose when we first smelled it.
So we are assume the voltage regulator is fried, faulty or installed faulty.

SO if anyone knows how to get a replacement, or repair let us know.

[keen101]

you just need to somehow find a replacement 5V regulator and replace the old one.

I recommend using a solder sucker to remove the old one. as for finding a 5V L805 or equivalent... I have no idea where to find one. I just salvaged one from some old board lying around. I looked at Radio Shack, but I did not see any.

I have already fixed our board twice. It was the 5V regulator both times.

It's too bad FIRST did not design the board with a diode to prevent accidental reversed polarity.

[Phalanx]

Is there any major reason that a 7805 From Radio Shack couldn't be used as a replacement voltage regulator?
http://www.radioshack.com/product/in...rt&tab=summary

The only difference I can see that the factory LM78L05 is limited to 100mA and the 7805 from Radio Shack is 1A. Would this be a bad idea?

Thanks,
Michael

[keen101]

hmmm......... it might have been the 7805 one, that I used. I can't remember, and I don't have my board with me right now.

[Richard McClellan]

You'd have to make sure that the pins on the connector would actually fit in the holes for the regulator, but other than that, it should work from an electrical standpoint.

However, I don't know if this would be allowed by FIRST rules, so I would contact them first.

[dlotts]

Our board worked for at least 30 minutes. Then the next time we tried it appeared completely non-functional, with no LED's lighting. Maybe the ground and plus voltage got switched one time, we don't know.

We tested the voltage at the inputs, and they were correct.

Then we tested the voltage across the PIC chip at the Vdd and Vss pins. It showed a consistent 0.36 volts -- way lower than the expected 5.0V. We read the same voltage between the ground and the output of the regulator.

We de-soldered the regulator, and replaced it with a larger 7805 regulator that we had on hand, probably 1 Ampere. We used short pieces of wire so we didn't have to make the larger part fit.

Since we'll probably want to have a second one on hand at the competition, we figured we didn't have much to lose by attempting to repair it.

Then the school kicked us out and we didn't get much chance to clean up our solder and try it.

I'll let ya know how this worked out later.
MrLotts.

[RyanN]

Originally Posted by dlotts

Our board worked for at least 30 minutes. Then the next time we tried it appeared completely non-functional, with no LED's lighting. Maybe the ground and plus voltage got switched one time, we don't know.

We tested the voltage at the inputs, and they were correct.

Then we tested the voltage across the PIC chip at the Vdd and Vss pins. It showed a consistent 0.36 volts -- way lower than the expected 5.0V. We read the same voltage between the ground and the output of the regulator.

We de-soldered the regulator, and replaced it with a larger 7805 regulator that we had on hand, probably 1 Ampere. We used short pieces of wire so we didn't have to make the larger part fit.

Since we'll probably want to have a second one on hand at the competition, we figured we didn't have much to lose by attempting to repair it.

Then the school kicked us out and we didn't get much chance to clean up our solder and try it.

I'll let ya know how this worked out later.
MrLotts.

This sounds exactly what happened to us. Please tell us if you get it working. Also, I called FIRST yesterday, and they said they sent a shipment of the IR boards to Innovation First, and that they should appear some time today. Whether or not this is true, I'm going to keep on eye open for them.

[keen101]

Originally Posted by Phalanx

Is there any major reason that a 7805 From Radio Shack couldn't be used as a replacement voltage regulator?
http://www.radioshack.com/product/in...rt&tab=summary

The only difference I can see that the factory LM78L05 is limited to 100mA and the 7805 from Radio Shack is 1A. Would this be a bad idea?

Thanks,
Michael

If you can get it soldered to the board, then I think it will be fine. I think it's perfectly legal, since you aren't changing the function of the IR board. It is certainly a beefier regulator, but it should work.