How to use LSS adapter board correctly

Please let me know how to use LSS adapter board correctly.

I am using LSS Arm 4DoF connected to PC via LSS adapter board. I am using the following LiPo battery for power supply.

GOLDBAT 1500mAh 3S 100C

Three LSS adapter boards have failed since I started using it in August last year, and now I am ordering the fourth one.

The first and second LSS adapter boards were working fine for two months, but then the servos stopped responding. We have already confirmed that the communication is bad by LSS Flowarm and LSS Config.

When the third LSS adapter board was connected to a LiPo battery, smoke rose from the circuit and IC1 near the XT60 connector burned red, causing the circuit to heat up. This ignition phenomenon was also observed on the second LSS adapter board. The adapter board is stored in an acrylic case to prevent short-circuits in the circuit.

My question is, what is the cause of the above ignition phenomenon? Also, what should we pay attention to in order to prevent ignition and communication failure?


Welcome to the RobotShop Community :smiley:

To better understand the issue you are encountering with the LSS Adapter, please provide the following information:

  1. In what situation you noticed that the IC1 (5V linear regulator) is started to burn ? For example: directly when you plug the LiPo battery or after a certain period of time or when you plug the USB cable, etc…
  2. Are the LSS already plugged in the LSS Adapter when you have connected the Battery ?
  3. Could you provide a clear picture showing your current setup ? (LSS Adapter, Battery, Servos, etc…)

Thanks for the reply.

With the LSS arm and LSS adapter board connected, I connected the battery to the XT60 connector and it fired right up.

I am attaching a picture of our system.


Thank you for the pictures. We were able to reproduce the issue. We are investigating the potential causes. We will get back to you asap.

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@chishiro After investigating the issue, we have found what is causing the failure you experienced. Long story short, the parasitic inductance of the Lipo battery leads/connector in combination with the input filtering capacitor C1 of the 5V voltage regulator and it’s low ESR rating (Equivalent series resistance) creates an LC circuit on the 5V regulator input that generates a destructive LC voltage spike when plugging the battery.

The voltage spike rises up to 20V with the Lipo battery which is above what the 5V regulator can handle as input voltage (a maximum of 18V). This LC voltage spike might damage the voltage regulator IC1 instantaneously.

The voltage input when plugging a Lipo battery can be seen in the following oscilloscope screenshot (yellow graph):

This being said, having the LSS servos (one or more) connected to the LSS Adapter before plugging the Lipo battery dampens the LC voltage spike and saves the 5V regulator in most cases but also helps hiding the problem. We are currently working on a permanent solution for this. As soon as the solution is implemented, our customer service department will contact you and replace the LSS Adapter for you free of charge.

Thank you for letting us know about this

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This topic was transferred to internal RobotShop Support.