LimeSDR-USB no power

My LimeSDR has stopped working and has no LED activity when power is applied.
The unit has only been connected to a USB3 computer interface and the external power input has never been used. I have searched DISCOURSE for troubleshooting advice and found No power for a new LimeSDR
I tested the voltage on the FR38 component and measured 5.29 VDC on the side closest to the external USB connector and 0 VDC on the other side. Any help would be appreciated.

@Zack anything to suggest?

Are there any other test points to measure that would help isolate the problem?

Hi @bljohnson44,

  1. Test FR38 for continuity.
  2. Check if there is continuity from the FR38 (side you measure 0V) to the ground.


  1. FR38 measures 1.25M ohms
  2. The 0VDC side of FR38 to ground measures 0.2 ohms

I believe the measurements were made correctly, do those values provide any insight?

Hello @bljohnson44,

It looks like FX3_VBUS line is shorted to ground probably via FX3 chip. FR38 is out of order. Looks like FX3 needs to be replaced as well as FR38. Probably there is more damage in the circuit too.

Well that is bad news, thanks for the diagnosis Zack.
It sounds like the situation is beyond my ability to remedy.
Is there any way to have the unit repaired?


This is very concerning as I don’t recall an “event” that would cause such damage (power outage, storm, etc.) This LimeSDR lives in a computer lab environment (normal temperature/humidity environment with UPS mains) connected to one computer and has less than 60 hours of “on time”. The USB interface has been connected/disconnected <15 times in total.

Is there any way to have this LimeSDR repaired?

Thanks for the support. I’ll be pitching this in the bin, what a waste.