No Power on Aux or Main Molex Connectors

Hello, we are attempting to power a LIDAR unit from the AUX connector, and I’m not able to measure any voltage on either the AUX or MAIN molex connectors. The indicators for 5V and 12V power are lit. Any troubleshooting ideas on what to look at next?

Edit: I should mention that it’s a REV5.3 board and all other functions appear to be working.

To be clear the robot is driving, i.e. the RPi is getting power, you can connect to it via wifi?

There is no 12 or 5v on either of the auxillary connectors?

Are you getting at least 24v from the batteries?

There is a main fuse on the board, but you shouldn’t get any leds lit if this fuse is blown.

If you could take a photo of the board and LEDs when powered on, that would help.

Also see if you can get the results of rostopic list and echo of /battery_state ??

This sounds very strange. The only thing similar is low voltage, but in that case the robot would not drive, and you would not be able to communicate to the MCB.

Also, if you are equipped with an OLED display, what does it show?

Re-measure power on the Main Connector but measure from either of the center 2 pins that are ground to the 12V and then to the 5V side. You cannot measure power with the assumption that the robot chassis itself is ground, it is not ground.

The robot systems themselves use 5V and 12V power, so there must be power there on the board if the robot is operational. It would be shocking if the robot is working and the 4 power leds are good and on but you see no power on the Main and the Aux jack.

Also just do some sanity checks

  • Verify your meter as well I guess.
  • Verify the solder is seen on the back of the board under the Main and Aux power jacks

One other thing to bear in mind is that the main board also has 5V and 12V pads available to solder directly to. If looking at the robot head on these pads are on the top left of the board and are labelled. You can check there too.

Lastly remember that there is a conformal coating on the board - this is there so that if you drop a screw on the board that it doesn’t short things out. The effect that this has is that if you make contact with your meter on the back of the board you likely will just touch the conformal coating which is an insulator and so will show no voltage. So you’ll need to check the voltage from the connector itself. The conformal coating is very thin and is transparent - so it may not be obvious.