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HELP! my 301 is not switching on



I know you probably don’t want to hear this but do you have another power supply or trying the er301 by itself after unplugging all the other modules. My one was reacting exactly like that and it was due to too much strain on the +12 rail even though I was well within the parameters of my power supply :frowning:


Hope you’re wrong, weird how it all of a sudden started happening after quite some time behaving normally.

How much was your row pulling versus your available power etc? Mine is 1.2 vs 2.6 or for the row in question : .6 vs 1.3. Seems bizarre that under half would trigger issues like this.

What have you done about it?


I too was having similar problems as you so I switched from 5V to the 12V power source and the problem went away, though my system has plenty of power. I have 10A and I’m using 8.1A but it appears that sometimes things can get finicky regarding power demands.


Well I have 5v power but have it set to Reg already as that seems to be safer option


Good morning and thank you for the test results. Some more requests:

Could you do me a favor and zip up the contents of your rear SD card and send it to me?

What is the time-to-failure if you put your ER-301 in your big case?

Please PM me with your current shipping address.


Seems your flying low under your limit but honestly you need to give it a shot, buying an olimex or returning for a service will be time consuming.

Really didn’t like the dc800’s especially was really poor for providing +5v. DO NOT flip your 301 to +5v using it, you’ll more than likely not have enough juice to run it.

I changed to 4ms row 40 which wasn’t great either. Ended up with intellijel tps80w. 3a per board and has tons of headers. No problems so far.


Power is my biggest beef with the eurorack ‘standard’. It’s so wild west in what you can get and the inconsistency of quality is pretty scary.


It only lasted for 1:20 in the big case. That has 4 Dc800s split over two cincons. The row I put it in is blank but a single TTA BD808 module, so I don’t think this is a power issue.
Big case looks like this https://www.modulargrid.net/e/racks/view/578681 and I tested the 301 in the top row.


What a nightmare, glad you got it sorted.


Just for the record, I power 2 ER-301s (and a load of other stuff too) from a 4MS Row 40 - zero issues!

I did have a “oh whoa… oh wow” moment the other day though - because of how I live I am on a three phase electric power supply, so AC/DC conversion is going to be really good!

I realise this is of absolutely no use to anyone, but the more I learn about power the more I realise that mains electricity can be very bad quality and this can be the cause of many problems.


I agree! :wink: but keep in mind that we were testing for more than just power capacity. You can have a hefty power supply that can provide all the current that you need but if the voltage is fluctuating too much around the required value then it will also cause similar problems. There there is a whole host of other potential problems caused by poor wiring or faulty capacitors that develop into faults over time. The ER-301 by its very nature often acts as the canary in people’s cases being the first to be affected by power system trouble.

I know it took time but I appreciate your being a good sport and performing the requested tests. Users are often ruling out power too early because “it’s always worked before” or “I should have plenty of capacity” so it is often a bit of an uphill battle for person trying to debug the problem remotely (as you might have noticed). :laughing:

Since we’ve ruled out power trouble to a good degree and verified the rear SD card, the next step is to see if the replacement CPU board will solve the issue.


Totally agree. I think the power situation is down right unbelievable. With systems costing 10 to 20k it is just hard to believe that power problems are still an issue.

The other sad thing though, is when people introduce new power solutions people come out of the wood works and try to disparage them, even though despite the accusations the product is still an improvement from what is available. I will admit that certain people stoke these fires on purpose, but honestly it seems like a lot of the improvements people try to bring to the table within eurorack are just always attacked by the modular community.

Back on topic: Glad a solution has been determined! Trying to diagnose modular problems over the internet seems like it would be exactly like trying to diagnose computer problems over the phone.



I second this, but would like to add that it is just certain members of the community, many of which have their own horses in the race, it’s nothing short of bullying in my view. I have been on the receiving end of it too, it’s seriously not cool! I would never buy anything from the people who do this, so they are only shooting themselves in the foot :wink:


That usually comes down to the user though - 15.5k of modules and sure, $500 will do fine for the most important part… riiiiight?? Nope! It’s usually skimped on because power and distribution are invisible and don’t have blinky things or CV control :wink: :smiley:


I agree with your general meaning, but disagree at the notion power should scale with the cost of the system. A good solid power solution should be a static price and not one that scales, unless you need more power in which case you just buy another. In this sense it is scaling, but it is more of a 1 + 1 = 2, and not 2 * 2 or 4^2.

Also the reason why this mindset kind of persists (that power is an after thought) is that most newbies to modular are coming from a world that actually has regulated power and conforms to federal regulations (US specific here, although I know Canada does likewise). You DON’T have to think about power! You just trust that the power supplied with your synth works well, and SURPRISE, it does!

Also power in eurorack is not JUST the power. It’s the case. It’s the modules in the case. It’s your house and wiring. It is a tough nut to crack, and demonstrates time and time again why modular synthesis kind of died out in the past. It is also why I think companies don’t take modular completely serious. This is specifically a problem that needs a real serious solution, and it isn’t just going to be the the power supplies but a majority of the module manufacturers out there to actually fix.



I should have worded that better. Cost no, size yes (but these tend to climb up together. I just see time and again people blowing up i.e.: uZues’s as specs aren’t checked and they wonder why it dies when there’s 1 or 2 metasonix modules in the case :wink:


EThe 301 is back in action! the replacement cpu board did the trick, or at least so it seems. Good to have it back!!