Asked — Edited

Power Question

Hello everyone!

I am experiencing a problem with the power supply for my Robot. My EZ-B is adjusted for an external power supply on ports d0- d14, to which 12 high torque servo's are connected. I have 2 LiPo batteries of 7,4 v connected in paralel, directly feeding the EZ-B and a Castle Creations Bec that is set to its standard setting of 5,1 v. The bec is then connected to the digital ports d0 - d14 on the EZ-B.

Everything seems to be working fine, initially. the bec's green led is on, indicating it is functioning properly. Then when powering the EZ-B and its components are also functioning properly. But when I connect the bec to the port for the high torque servo's suddenly the bec's led starts flickering very faintly and I hear a slight rattle in the servo's with it. Though the EZ-B is still functioning at this point, the servo's do not respond in any way.

I measure the voltage on the ports powered by the bec and it measures 1,25v. I then disconnect the bec off of the ports and everything works fine again, the bec's led lights up constantly and bright as it should. The EZ-B is still on at this point and I measure the same ports without the bec and I would expect there to be no voltage since I have cut the lead for the external power, but it then showes that there is still 0,40 volts on these ports.

Ive measured the outgoing power on the bec while it is disconnected from the servo's and it does measure 5,1 volts. but when i connect it to the ports for the Servo's it again starts rattling and faintly fickering the led. The ports measure 1,25v. I then take the power off of the EZ-B but leave the bec on the servo's and still those ports measure about 1,25v and the bec is still doing it's rattling thing.

So I check to see if I have properly cut the lead on the EZ-B board and I can't see how it could possibly still be making somekind of connection to anything else on the board, it's cut alright. With power on the board though, the ports still have a 0,40 v on there.

So I am confused. What exactly is going on here? Any help would be very much appreciated.

Kristian. :)


I've taken care of the 0,40 v on the ports, I guess it wasn't cut all the way after all. They now read 0v when the EZ-B is powered. Still though, when I connect the bec to the ports it's starts acting up and measures 1,25v. I do not understand.


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I'd suspect some capacitors and/or resistors may still be connected to those pins. Follow the traces from each 5v pin, both top & bottom to be sure nothing else is connected.