Servo Motors Not Running

MythCrane

Hi there, I have a Basic Stamp Board of Education and I cannot seem to get servo motors or brushless motors running on it. However whenever I run a DEBUG program
or an LED program it works. Is there some problem with the servo motor connection area or is the board damaged. Thanks.

MythCrane

Update: If I use jumper cables to connect the servos and brushless motors to the Board of Education it will run. However, if I connect
servos to the servo headers it will not run. In the brushless motors case, if I connect them to the servo headers they will beep on and
on and on.

Electrodude

Is the power switch on 1 or 2? It needs to be on position 2 for the servo ports to work.

Are your batteries dead? Try a wall power supply if you haven't already.

MythCrane

Electrodude wrote: »

Is the power switch on 1 or 2? It needs to be on position 2 for the servo ports to work.

Are your batteries dead? Try a wall power supply if you haven't already.

We have tried a wall supply as well as 9 volt batteries and a LiPo battery which is fully charged. Also I do put the switch on 1 and two.

MythCrane

MythCrane wrote: »

Electrodude wrote: »

Is the power switch on 1 or 2? It needs to be on position 2 for the servo ports to work.

Are your batteries dead? Try a wall power supply if you haven't already.

We have tried a wall supply as well as 9 volt batteries and a LiPo battery which is fully charged. Also I do put the switch on 1 and two.

Also to add the LiPo battery is 11.1 volts.

Electrodude

What do you get if you put the power switch in position 2 and then stick a voltmeter across the red and black terminals on the servo port?

What position is the jumper between the two servo ports in?

MythCrane

As for a voltmeter I believe I do not have one. What about a multimeter? If they are the same thing then I will try.

Electrodude

Yes, I meant a multimeter in voltmeter mode.

Your jumper is in the right position. Do not switch the jumper to the other side, or you'll probably damage your servos with 11.1V.

MythCrane

Ok, when I tried the multimeter on the terminals 12 and 13 worked but 14 and 15 did not connect. Another thing to realize is when we test the positives on 14 and 15, they show voltage. It is only the negatives that do not show any power flow.

MythCrane

I mean resistence

Hal Albach

Are you saying that when reading resistance from the servo ports black(ground) to the board ground you are not showing any resistance? The reading should be similar to when you just touch the multimeter probes together. Can you post your program?

MythCrane

Yes and no. I ran two tests. One was a voltage test and one was resistance test. When I ran a voltage test power was flowing through
terminals 12 and 13. When I performed a voltage test on terminals 14 and 15, it would not show any signs of power. So then I decided to perform a resistance test to see if the positives are connected to the positive of the board. For all four terminals, there was resistance when connected to the positive. When I checked the negative for resistance there was no signs of resistance in terminals 14 and 15. This leads me to believe that terminals 14 and 15's negative parts are damage.

Electrodude

Either you don't understand resistance or I don't understand what you're saying. No resistance, i.e. the ohmmeter displays 0.00, means they're connected together. Resistance means it doesn't display zero; if it says "1. " i.e. infinity, there's no connection at all. In reality, there's no such thing as zero resistance; it's at best very small.

What does your ohmmeter display when you connect it between 14 or 15's ground and the power jack's ground? What about between 14 or 15's power and the power jack's VIN? Make sure there's no power applied when you do this. Also make sure the switch is on; if it isn't on, there won't be a connection between certain points.

MythCrane

I am using an analog multimeter. So when I say there is no resistance, I mean my multimeter's dial is not moving when I test for resistance.

Electrodude

Oh, OK, sorry. I must have misread your earlier post about your voltage tests. Yes, it sounds like something is wrong with 14 and 15's grounds.

Can you measure the resistance at other pairs of points, such as across 14 and 15's grounds?

robotechplace

Besides 14 and 15's ground, it could be that the Basic Stamp isn't closing 14 and 15 or the voltage regulator is damaged. If 12 and 13 are working, then it can't be the voltage regulator. You can check for 14 and 15's open or close status in the Basic Stamp by testing for voltage in the regular pins 14 and 15 (the regular pins not Servo Drivers 14 and 15) with switch set to 1.

Chances are that the LiPo may have affected the Servo Drivers 14 and 15 (despite the voltage regulator) and so yes, 14 and 15's ground may be damaged; though I'm unclear why the multimeter is reading on positive, but not grounds for (all) 12 to 15.

erco

Mythcrane: Sounds like you may have multiple issues. Suggest you post detailed photos of your entire setup: BoE, wiring, batteries, and servo.

Hal Albach

The ground to the servo ports are hardwired into the board ground. Since resistance checks indicated that Ports 12 & 13 grounds were intact would it not be a simple matter of soldering a short bus wire across all four of the servo port ground pins and restore Port 14 & 15 functionality?
MythCrane: When you performed the resistance checks on the servo ports did you have the meter set to the lowest range? Can you visually inspect the solder connections for the two affected pins (probably on the back of the board) ?