Nebra Miner Offline – Solved

If your Nebra Helium miner is Offline and not earning any HNT there are a few things you can try to resolve the problem.

Take a look at the LED lights on the back panel of your miner.

Nebra panel LED

It is normal for the green light on the back of the unit to blink rapidly about 8 times with a few seconds interval. This is the expected behavior.

There is an orange or yellow LED below the green light and if that is off or both LEDs are off, then there’s an issue with your miner. Here’s what you can do to solve this problem.

The first thing to do is power down the miner. Then open the lid of the miner (you don’t need any special tools for this) and re-seat the Raspberry Pi compute module. Power the unit back on.

If the problem persists – that is, the Yellow LED is off, then it’s most likely an issue with the eMMc card shown in the picture below [blue rectangle]

eMMc card in Nebra

You can contact Nebra [email them at sales @] for a replacement card. Note however that it will take around a month for them to send it out. If you don’t want to wait that long, then you can simply purchase a replacement card from eBay. The 64 GB SD card is a cloned version of the eMMc card and works quite well. Some Helium miners have reported improvements in mining performance once this change is made.

Nebra eMMc card SD card

Once you receive the SD card, you can replace the eMMc card with this one and you should be back up and running in no time.


What is an eMMC card?

eMMC is short for embedded Multi-Media Card. This hardware package consists of both flash memory and a flash memory controller integrated on the same silicon die.

The eMMC solution consists of at least three components –

  • MMC (multimedia card) interface
  • Flash memory
  • Flash memory controller

The small form factor of the card makes it ideal for many small electronic devices. It’s labelled “embedded” on account of the fact that it is usually soldered directly onto the device’s motherboard, so it is not removable nor displaced easily. Reference.

In the case of the Nebra miner, the eMMc is soldered on to a separate removable printed circuit board. The small PCB is designed such that it is removable as shown in the picture above.

eMMc technology was likely chosen for this design on account of its lower price relative to the SD card. However as we have seen in this case, the design was not robust enough and there were many failures costing the company time and money to ship replacements.