Er-301 FAQ

I’ve been seeing the same questions come up a few times and thought it might be a really nice idea to start an FAQ wiki. As I come across things I’ll edit this post, all contributions welcome :slight_smile:

Please don’t use this thread if you have a question not listed here. The search functionality is excellent, try there and if nothing then start a new thread - thanks!


How much power does the ER-301 need?

When the 5V source is set to BUS:

120mA @ +12V
20mA @ -12V
320mA @ +5V

Which power setting should I use?

It won’t matter either way to the ER-301 because all rails are regulated and filtered before they get to any sensitive circuitry. The switch is really just there to give you options. The many variables in a eurorack power system make it exceedingly difficult to give hard rules but here is a try:

Is your 5V rail produced by simply linearly regulating down the 12V rail?

Yes - Then use the REG setting because the regulator inside the ER-301 will be much more efficient and produce a lot less heat. Stop here.
No - Keep going.

Does your 5V rail have at least 320mA of unused capacity?

Yes - Then use the BUS setting. Stop here.
No - Keep going.

Does your 12V rail have at least 300mA of unused capacity?

Yes - Then use the REG setting. Stop here.
No - You need a bigger power solution for your case. Stop here.

Can I switch Power Settings While the ER-301 is Powered Up?

NO. Do not switch the 5V source while the module is powered up. You might cause arcing in the switch which will reduce its operating life.


How to Install Firmware on the ER-301:

  1. Download the zip file of one of the release files.
  2. Copy the zip file (without unzipping) to the FRONT microSD card. :apple:
  3. Power up and insert the microSD card into the FRONT slot of the ER-301.
  4. Move the STORAGE switch from EJECT to ADMIN (i.e. mount the card).
  5. Navigate to the UPDATE FIRMWARE screen (all the way to the right).
  6. Press UPDATE.
  7. Select the zip file that you copied in step 1.
  8. Once the files are installed, press REBOOT.

:apple: Mac-users: Your browser might automatically try to unzip the file for you when you download. To prevent this, please right-click and choose “Download Linked Files”.

The Emergency Manual Firmware Update Procedure

(This is not the normal firmware update procedure! You only need to do this if the regular updater using the FRONT card fails for some reason.)

  1. Download the firmware archive that you want to install and unzip its contents on your PC.
  2. Unscrew your ER-301 from the case and look at the back. There is a SD card on the back. I will call this the REAR SD card. Take out the REAR SD card and bring it to your PC.
  3. Using your PC, copy the 3 files that were in the firmware archive (MLO, SBL, kernel.bin) to the root directory of the REAR SD card of the ER-301. You will overwrite the 3 files on the card already and that is OK.
  4. Put the REAR SD card back in the ER-301 and power up. You are done.

Hi @anon83620728. I’m using a Meanwell RT65 power supply. Do you have any idea if the above applies to it?

No clue sorry… never even heard of these! I’d look for the spec sheet or contact the manufacturer for details :slight_smile:

Sorry, obviously wasting my precious time here… Apologies to everyone, I won’t do it again I promise!!

See, the official WIKI:

Definitely not! This topic was the main reason why I got off my butt and made the wiki in the first place. :smile_cat:

1 Like

Great :smiley:

Sure, that’s clearly a much better solution!!

…but obviously now superfluous, so this post can drift off into history!

[confucious on]
Precious contributions deserve a nice place to live.
[confucious off]