This article includes the following information about the various electronic boards on the OT-2:

  1. Video analysis

  2. Analyzing the electronic boards

    1. Motor controller board LEDs

    2. Central routing board LEDs

    3. Raspberry Pi LEDs

This article is intended to provide guidance on how to analyze the electronic boards on the OT-2 for troubleshooting purposes. Refer to hardware troubleshooting before getting started if needed.

Video analysis

Opentrons Support may request that you send us a video of the OT-2 boards to help with troubleshooting. When we review the video, we look for specific LEDs on each board (shown below) to determine if everything is powering on properly and/or if there is a problem detected indicated by the light.

Analyzing the electronic boards

Motor controller board LEDs

Power LEDs (36V, 10V, 3.3V): All three need to be on for normal operation to be possible. If any of these LEDs are out, a power regulator may have failed and hardware replacement is necessary.

  • 36V LED - This LED indicates 36V power is reaching the stepper motor driver board. 36V LED being off does not necessarily indicated the stepper motor driver board has a problem, the issue may be in the boards that supply power or loose/faulty cables.

    • Check if central routing board power LEDs are on:

      • If yes, the power cable is suspect; consider reseating it. If the cable is damaged, replacement may be required.

      • If no, turn off power then disconnect the stepper motor driver power and data cables. Turn the power back on and check for the following:

        • If central routing board power LEDs turn back on, the stepper driver board may need to be replaced

        • If central routing board 36V power LEDs are still off, the issue is not likely the stepper motor driver

  • 10V LED and 3.3V LED - These indicate the onboard power regulators for these voltages are working. If either of these LEDs are off, the issue is in the stepper motor driver board and it should be replaced.

    • If the 10V LED is not flashing, the motor controller board may need to be replaced because the regulator might have failed.

Red “Play LED: To the left of the microcontroller unit (MCU), this LED turns on when movement code is being executed. It's not incredibly useful for debugging as the robot not moving will probably be the first symptom that is noticed.

Green/blue “MCU operation” LEDs (four total): These LEDs should be solid or blinking while code is running on the MCU. If they are off, possible issues include:

  • Firmware is not loaded onto the MCU

    • This could indicate a communication issue preventing the Raspberry Pi from flashing the MCU.

  • MCU is stuck in reset/boot mode

    • This could indicate a hardware issue with the reset/boot signal lines going to the stepper driver board.

Serial logs should help determine if there is a communication issue. Reseating cables is also worth attempting. Beyond this, specific boards may need to be replaced and Opentrons Support can help you with this process.

Central routing board LEDs

Power LEDs (10V and 5V): These indicate the onboard power regulators for these voltages are working. If either of these LEDs are off, the central routing board likely needs replacement.

  • You should also check to see if power is actually getting to the robot (e.g. power connection inserted properly, blue LED on external power supply is on, and the power is switched on).

    • These LEDs will not illuminate if there is no power reaching the robot.

Raspberry Pi LEDs

Power LED (red): This LED must be on at all times or else indicated power is not properly being supplied. Power cable reseating, cable replacement, or central routing board replacement are possible fixes.

Activity status LED (green): This LED should blink occasionally in normal use. If it is stuck on green, you may need to reflash or replace your SD card.

Ethernet socket, left LED (yellow):

  • On = 100 Mbps connection

  • Off = 10 Mbps connection

Ethernet socket, right LED (green):

  • On = link is established

  • Flashing = for port activity

  • Off = no link is established

Note: The Ethernet LEDs may be hard to see with the RPi/stepper driver DATA cable in the way.

Additional resources:

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