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Servos wrongly connected — Parallax Forums

Servos wrongly connected

griegorygriegory Posts: 6
in BASIC Stamp
Hi,

I am resuming the programming of my arduino after years using the parallax manuals, but I am stuck in making the servos work.
I have a Basic Stamo Homework Board USB Rev A powered by a UC1.3-6(6V 1.3 AH/20HR) battery.
I can't remember how the servos should be connected to the stamp. I connected them as detailed in the manual (brown cable to Vss, red cable to Vin, orange cable to the pins) and when I power the board there are no lights twinkling and there's a very low whisle.

I hope anyone can help me with the way the servos should be connected.

Thank you all.
20190618_140145.jpg
4128 x 2322 - 3M
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4128 x 2322 - 3M
20190618_111857.jpg
4128 x 2322 - 3M

Comments

  • Mike GreenMike Green Posts: 23,101
    I have several servos and they all have Black (Vss), Red (Vin), and White (I/O pin) wires. From the photo of the servo wire, I suspect Brown connects to Vss, Red connects to Vin, and Yellow connects to the I/O pin just like what you tried. What program do you have running in the Stamp?

    Your battery puts out over 7V when it's fully charged. That's on the edge of what a servo motor will tolerate. They're much "happier" at 4.5-5V. What happens when you run the Homework Board with 3 or 4 fresh alkaline batteries in series?
  • griegorygriegory Posts: 6
    Hi Mike,

    Thanks for your feedback.
    I wasn't able to download any program to the Stamp, the software shows an error that says that there is no Stamp. I am using version 2.5.4 of the Basic Stamp editor.

    I haven't tried with alkaline batteries yet, but I think this is not a battery issue. I found my boe bot some days ago with both servos connected and the last program I downloaded to the Stamp (which I programmed some years ago) and everything was working fine. Then I disconnected everything to study everything from scratch but I couldn't make it with the servos.
  • PublisonPublison Posts: 12,366
    edited 2019-06-18 19:21
    The noise you hear might be from the regulator indicating the battery is connected backwards? Try AA batteries as Mike suggested. see if you can see the BS2 without the servo connected.
  • xanaduxanadu Posts: 3,347
    edited 2019-06-18 19:32
    Those 9v connectors are tricky... Take a multimeter and do a continuity check from the smaller of the two snap connectors to the end of the wires. You'll see the smaller connector is tied to ground (black). This is bad because a 9v battery ground is the larger connector. It is working in reverse because the connectors are designed to get power from the battery, not provide power to a device.

    Just noticed the battery is 6V, that might not be enough. Not sure.

  • PublisonPublison Posts: 12,366
    What is the voltage going to the servos? There are no servo headers on the homework board to supply 5 volts.
  • griegorygriegory Posts: 6
    Publison wrote: »
    The noise you hear might be from the regulator indicating the battery is connected backwards? Try AA batteries as Mike suggested. see if you can see the BS2 without the servo connected.

    I think the battery is ok because I have programmed the Stamp to control LEDs and provide feedback using the Debug tag and I had no issued with that, the only issue is that I don't remember how to connect the servos.


    Publison wrote: »
    What is the voltage going to the servos? There are no servo headers on the homework board to supply 5 volts.

    I connected the servo's red cable to Vin and brown to Vss and it measured 3 Volts
  • PublisonPublison Posts: 12,366
    griegory wrote: »
    Publison wrote: »
    The noise you hear might be from the regulator indicating the battery is connected backwards? Try AA batteries as Mike suggested. see if you can see the BS2 without the servo connected.

    I think the battery is ok because I have programmed the Stamp to control LEDs and provide feedback using the Debug tag and I had no issued with that, the only issue is that I don't remember how to connect the servos.


    Publison wrote: »
    What is the voltage going to the servos? There are no servo headers on the homework board to supply 5 volts.

    I connected the servo's red cable to Vin and brown to Vss and it measured 3 Volts

    Where is that voltage coming from, (picture needed). Servos normally need 5 volts to operate.
  • griegorygriegory Posts: 6
    Maybe I'm testing it in the wrong way.

    20190618_170559.jpg
    4128 x 2322 - 3M
  • PublisonPublison Posts: 12,366
    What pin is the Red lead plugged into?
  • griegorygriegory Posts: 6
    Publison wrote: »
    What pin is the Red lead plugged into?

    The (+)Vin pin
  • PublisonPublison Posts: 12,366
    Vin should read the input voltage of the battery. Does it read 2.9V if you disconnect the servo entirely?
  • griegorygriegory Posts: 6
    Publison wrote: »
    Vin should read the input voltage of the battery. Does it read 2.9V if you disconnect the servo entirely?

    Disconnecting the servos it reads 4.6V
  • PublisonPublison Posts: 12,366
    4.6 volts from the battery will not even power up the Homework board. You need 7.5-9 volts.
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