Voltage Problem


Although my tilt servo, motors and lights worked previously, they don't work now. The cockpit otherwise seems to work, or at least I make the connection and have the camera. The cockpit shows all 0's on the bottom bar, including 0 volts and a red battery indicator. But I have verified that I am getting 12.4 volts, with the correct polarity (pins 5 and 6 are +, pins 4 and 7 are -), on the DB25. Any troubleshooting tips would be appreciated. I am very close to my first water launch. Thanks, Rick


Hi Rick

If you have the camera and cockpit up then the BBB is working ok. and everything else works off the controller. The BBB is powered by +5v from the Controller so we know that 5v regulator is working.

you should check to make sure you have 3.3V on the controller using a volt meter. Because the motors and servo are not working I suspect that the +12V is not getting turned on to the ESC's which then gives +6V to the Servo via the BEC. There is a Jumper 17 on the control board that you can plug in that turns on the power to the ESC's if that does not work then there may be a problem with the power switch. You can use your volt meter to test for +12V on the ESC or if you can read a schematic diagram you can look for the test points to do this.


Thank you for the advice, David. I will try your suggestions, but I will probably not have a chance before this weekend. Do the lights also depend on 12v getting turned on to the ESC's? I ask because they are also not working. I appreciate you advice -- Rick


Hi Rick

The Led Modules are driven by PWM 1 it gets its +12V from V Bat/4.1B The Esc's get +12V power from 8.2A there are two power switches that turn on two +12V power sources. The Jumper J12 manually turns on V Bat/4.1B & J17 turns on +12V power to the ESC's Line Esc_Power/ 8.2A

So try installing both jumpers for testing this basically bypasses the Power switch controlled by the tether.

I would also unplug and turn off all the ESC's except one

After knowing that we have all the correct voltages then you can troubleshoot why the controller is not communicating with the BBB. this may take us back to reloading the Arduino Code.

But because you had things working at one point in time and now nothing works I am now thinking that maybe you have a short in the wiring harness or between the wires of the ESC's where they solder onto the board.

A few things you can test with a ohm meter.

Remove the DB25 harness connector from the controller.

Measure the resistance between each winding of your motors they should read around .4 ohms between any of the 3 Leeds.

Measure the resistance on the DB25 connector on the controller board between the ESC outputs by looking for a short "0 ohms" maybe check between +12v on the ESC to the output leed next to it checking for a short. or use a strong magnifying glass to look closely at the leeds of the esc's where you have them soldered to the control board looking for stray strands of wire that may be touching it's neighbor.

There may be fuses on the control board that have blown because of a short, but I would have to look further at the schematics to find them it indeed they are there.

first we need to make sure you have all your voltages.


Hi David,

Wow, what a great reply. Thank you. I will do everything you suggest. Unfortunately, I pretty much only have weekends to work on it, so I am glad for all the additional suggestions you provided above.




If the cockpit is on, but you are not getting telemetry on the right hand side of the screen, then likely communication with the Arduino has failed.

1. Check the /var/log/openrov.log file. See if you are getting log messages regading a Watchdog timer. That would indicate the arduino is locking up and restarting which is possible if there is a wiring fault.

Try re-flashing the Arduino from the Settings tab and then power cycling everything.