# Help with Parralax board and power connection



## consultlkr (Sep 9, 2008)

I am using a 5v 3.7a power supply (http://www.allelectronics.com/make-a-store/item/PS-537/5VDC-3.7A-SWITCHING-POWER-SUPPLY/-/1.html) from allelectronics.com.

It has an RFI/EMI filter near the end. Do I need to cut and strip the wire before or the filter?

There is writing on one of the wires, so I assume it is positive, but I don't own a meter to test it with. If anyone else is using this supply, can you tell me which wire is positive and which is negative?


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## bfjou812 (Aug 15, 2008)

consultlkr said:


> I am using a 5v 3.7a power supply (http://www.allelectronics.com/make-a-store/item/PS-537/5VDC-3.7A-SWITCHING-POWER-SUPPLY/-/1.html) from allelectronics.com.
> 
> It has an RFI/EMI filter near the end. Do I need to cut and strip the wire before or the filter?
> 
> There is writing on one of the wires, so I assume it is positive, but I don't own a meter to test it with. If anyone else is using this supply, can you tell me which wire is positive and which is negative?


According to the description in the catalog, the center is positive,which is the part that has the ring around it. If you have a countinuity checker you can find which wire is the positive one. As for the filter, I'm not real versed in that departrment ,but what I remember is that they help reduce noise and give a cleaner supply of voltage. Hope this is of help.


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## consultlkr (Sep 9, 2008)

*it's just not working*

I decided today to just go by a multimeter so i could test the wires, rather than take a chance. Sadly, after connecting the power to the board and hooking up the motors and USB, the motors do nothing.

I setup and ran the Parallax software to test the range, and i get no movement at all. I can see the commands flashing the light on the board, so I know that it's communicating. I'm completely stumped, not to mention frustrated.

Is it possible I just have a bad board?
Does anyone have any ideas on how I can troubleshoot this?


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## Dr Morbius (Sep 21, 2004)

Make sure you have the correct USB drivers. There is a link on the Parallax site fro the drivers, so make sure you install them. Otherwise everything should be working. If not, swap out your power supply. Try a used computer power supply, I use them they work great for servos.


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## hedg12 (Jul 6, 2008)

The filter is just a ferrite ring. It's not necessary, but it won't hurt to keep it on.

You might want to double check your port settings. The parallax looks to the operating system like a serial port, but when it installs it doesn't always default to com 1. Go into the pc's system properties and verify the port number in the device manager.


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## bfjou812 (Aug 15, 2008)

Are you using the PSCI software or VSA? Either way you have to select a com port,as hedg12 stated. If you are using the PSCI software I think you have to set the "frame " to zero where it says Go to, That is the starting point I believe. Then where it says servo rate I usually put in a value of 10 - 15 , because it is a slow movement, and if you screw up on going past the limits of the servo you can still save it. Just 1 last question, are you using a "motor" or a "servo" ?


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## Dr Morbius (Sep 21, 2004)

hedg12 said:


> The filter is just a ferrite ring. It's not necessary, but it won't hurt to keep it on.
> 
> You might want to double check your port settings. The parallax looks to the operating system like a serial port, but when it installs it doesn't always default to com 1. Go into the pc's system properties and verify the port number in the device manager.


Com1 is usually the rs232 serial port...NOT a USB port..which begs the question, are you using a USB or SERIAL Parallax board? Either way, hedg is right, check you com port settings both in the device mgr and also the software you are using..also make sure you pick the correct baud rate in the settings.


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## consultlkr (Sep 9, 2008)

Thanks for your suggestions. I double checked my configuration against all of them.
I'm using Futaba Servos on the USB Parallax board. I presume that the wiring on the servo are white="s", red="+" and black="-". The jumper is off. Power switch is on, USB is plugged in. I see a red light on the board when the USB is plugged in.

I have already installed the USB drivers from the Parallax site and setup both the PSCI and VSA to use COM 10 (which is the port the Parallax is connected to). COM 10 baud rate is set to 38400. I tested with both VSA and PSCI and can see the green light flash on the board when i use either one, so the USB communication must be working. So I can only conclude that the board is either not sending the control signal to the servo's or the servo's aren't getting power.  

If i use my multimeter, should I be able to detect current on the board by touching the + and - pins on one of the channels?

UPDATE: I tested the voltage on the pins and I DO have power there. So now, the only thing I can try is a different servo. I don't know why that would matter, but it's about the only thing left I can think of. The Futaba website says the S3004 model tends to me a power hog, so I wonder if 3.7 AMPs is just not enough for them? I'll probably go pick up a HiTec 425 (or similar) today, just for grins.

By the way - I checked settings in device manager and the software, to make sure they are the same.


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## consultlkr (Sep 9, 2008)

*ANOTHER UPDATE:*

Well, I never would have guessed, but it appears that the Futaba S3004 Servos were the culprit. I can only assume that each servo draws more amps than my power supply could provide, which surprises me, since it is 5v 3.7amp. Either that or they are wired slightly different from the HiTec servos. Regardless, I purchased only 1 of the HiTec 425BB's to test, so now I'm back to the store to buy 2 more so I can move forward with my project.

Hopefully, this piece of information about the Futaba's save someone else the headache (and cost)!


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## hpropman (Jul 27, 2008)

I am surprised that that you had a bad S3004 servo I have used them and have had no trouble with them. As a test manually move the servo horn all the way to one side, It does not matter which. Then connect the power only to the servo (red +,black -) make sure the voltage is between 4.5 and 6 volts (check with your meter the output of your power supply). If the voltage is more the 6volts you may have damaged the servo. After you connect the power the horn should move to the center of its travel. 3.7 amps should be able to drive several servos by the way. Are you plugging the servo into a connector on the board? if so look at the connector plugs on the end of the servo and make sure that the power and signal wires are located in the same position on the connectors of the two servos, if not then that could be another reason it did not work also, the orientation that you plugged it into the board connector if you put on reversed that would cause it not to work as well. Try the power test if the servo moves it is probably good. then you will need to verify proper connections. Take some pictures of the problem we might be able to spot a problem that you might be missing.


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## bfjou812 (Aug 15, 2008)

Also along with what hpropman said, make sure you don't do somethihg as stupid as I did, plug the servo in on only 2 of the 3 pins on the servo board!!!!!????? They won't work that way!!!!! The wiring is the same as you stated before, Black is -, Red is + and White (Futaba) Yellow (Hi-tec) are the signal.


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