I have a Rackbrute 6U filled as below.

Earlier this week, I turned the power on then everything came on and suddenly went off.

After this, the brick power supply no longer lit up, even when trying alternative kettle leads.

I received a new power supply from Arturia yesterday and have just turned on the Rackbrute again using that new power supply.

Exactly the same thing happened.

I'm now unable to use the rack at all, and have a seemingly dead power supply brick.

I'm relatively new to this - what could be going wrong?

According to my rack on Modular Grid, I'm well within the power consumption of the Arturia rack.

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(By the way I've posted this on MuffWiggler too - desperate to sort!)

Step 1 - add up all of your modules' current draws, then increase that by 1/4th. That additional draw amount is there to deal with inrush current, which is what you get for the first fractions of a second when the rig is turned on. If the final amperage figure there exceeds the current ratings of the P/S, then you've probably found your problem, and you'll need to replace the Arturia supply with something beefier. If not, then...

Step 2 - After acquring a new supply, remove ALL modules from the rig, then take some canned air and blow out all of the headers on the distro. If there's a bit of wire or something else conductive in there, this should remove it. Shrouded headers are very convenient, they tend to prevent mispolarized connections or connecting a ribbon a step or two off from its proper alignment, but they can hide bits of crap...and if one of those is shorting something, that dead-short will do that. Once this is done, turn on the rig with only one module connected. If the supply blows again, the problem will be a defective busboard. If not, then...

Step 3 - Start adding modules one by one, checking power integrity each time you add a module. And before each time you do this, remove the ribbon from the module and visually check each ribbon beforehand to make sure there are no nicks in the insulation, no shorted-looking bits around the connectors, and especially nothing that looks burnt...as there's enough amperage there to melt insulation if there's a short. Having done this, then blow out the power connection on the module (AWAY FROM THE OPEN MODULAR! You don't want to blow something into the cab to start the whole mess all over again!), then replace the ribbon and connect the module to the busboard. Turn on. If nothing happens each time, then WIN!...you probably had something in a module header. But if the P/S blows up yet again after reinstalling a module, the fault is with that module and now you know who to contact about their defective product.

Yes, this sounds like a kludgy way of troubleshooting a power issue. But the fact is that a typical Eurorack contains so much that's going on on the inside that, without a test module (such as Synthrotek's TST or vpme.de's p0wr) that lets you check module functionality, this is about the only systematic way to do this. Annoying, yes...but it comes with the territory. One other suggestion would be to invest in a cheap multimeter. With that, you could check the busboard to see if there's any continuity between the "hot" rails and ground (WITH THE POWER SUPPLY REMOVED AND RIG OFF!!!). If you see continuity between those, then something's wrong as those rails should only connect through the components connected to them. And while the Arturia Rackbrute distro does have filtering, none of that should be a problem as long as you check for continuity in BOTH polarity directions; if you see what seems to be a short, then reverse the polarity of the multimeter probes...and if this persists, then it IS a short. If not...then no, you're just getting continuity through a polarized component, and reversing the direction of current causes the polarized component to block the multimeter's DC. That's what you want to see.

Which brings up another point that needs to be mentioned: modular synthesizers are NOT entry-grade technology. Not even close. While this all seems like plug-n-play stuff, really, it's not...and there's a certain level of technical capability that anyone considering getting into modular synths needs to have before spending that first dime on a new rig. Having a multimeter and knowing how to use it is important. Basic skills with electronics tools such as soldering irons and wire strippers...those come in handy more than you'd think, if just to repair patchcables. Understanding how to logically troubleshoot by elimination (what's going on above in this post) is an essential. And a good appreciation of what an amp or two of "low-voltage" DC is capable of is another essential...which, frankly, you don't want to obtain first-hand.

Hi Jmeager,

Perhaps it's as simple as that one (or more) of the modules was wrongly connected to the -12 V? It's usually the red line on the ribbon and usually the white line on the PCB board. Please check that carefully as well for each module and also against each of the manuals that usually comes with the modules to see where the -12 V is (or download them from the respective manufacturer's websites). Of course please follow the instructions above from Lugia too!

Before blowing up more power supplies, the best thing is to take your modular system to your dealer (if that's possible) and have them tested it, if they blow up yet another power supply at least it wasn't your fault ;-)

Kind regards, Garfield Modular.

+1 for Lugia's post.

The first thing I'd want to find out is if I had a dead or dying module that's tripping my power. Your power supply and case may not be the culprit. They may be doing what they're supposed to.

Also, depending on your country's power set-up... did you check any fuses in the system?

You're going to have to check your modules one or two at a time. Start with the oscillators and work your way down your typical signal flow. Once you have all of your oscillators checked, then go with the VCAs, then filters, and then finally everything else. Let's hope you don't have any bad modules.

The specs for the 6U are as follows:
5HP power supply delivers 1600mA +12V output, 1600mA -12V output and 900mA +5V output

Do the math on each one of your modules as Modular Grid isn't 100% reliable at calculating your power needs.

Related to this topic, I'm wondering if anyone knows what the red LEDs mean on the Rackbrute bus board. I noticed that in one of my blank slots there were (maybe) 3 LEDs lit up. I turned it off and emailed Arturia after reading the manual because there's nothing in there about these lights. I'd love to know if those are a warning or somehow indicate when I've skipped a power port on a row. Thanks!

These leds just indicate that there is power on -12, +12 and 5v rails. I would be more annoyed if they weren't on...

Given that the power supply eats 5hp and my planned design also exceeds the power specs by roughly 10 percent, I wonder what it takes to move to some external power solution, giving more power and saving 5hp. Has anyone done that?

Regarding the power specs: The Arturia reads 15V/3A on the frontplate, so that indicates the demand from the powerbrick. However, it´s only specified to deliver 12V/1.6A on the +12V distribution. That´s just half the amps... is this limited by the power module itself or is the distribution board limited to 1.6A ?

its related to the 1.6A -12v and 900mA 5v - don't ask me how exactly - but that is where the answer lies

there are simple answers to your problem - buy fewer or different modules - buy a different case - buy another case

The Arturia reads 15V/3A on the frontplate, so that indicates the demand from the powerbrick. However, it´s only specified to deliver 12V/1.6A on the +12V distribution. That´s just half the amps... is this limited by the power module itself or is the distribution board limited to 1.6A ?

No, this makes perfect sense. Remember, that power supply is also feeding a -12V rail plus the 5V rail. Each 12V rail has a possible maximum load of 1.6A, and the 5V rail can handle 900 mA.

However, if you're exceeding the current limits for your P/S, you're screwed. Your only solution is to add more current capacity via a second P/S, or to get a case that has a beefier power supply. You cannot exceed maximum rail loads without incurring some sort of problem...either damage to P/S components over time, or an outright P/S failure all at once. And depending on the power supply design, a "failure" might be more catastrophic than just popping the P/S itself.

NEVER come close to your power rail current limits. The proper rule of thumb is to exceed your rail load by at least 25%; if you have a load of 1A on your +12V rail, the power supply needs to be able to supply 1.25A. This is because, most of the time, manufacturers list the current load during operation and this doesn't reflect any inrush current loads that might happen when the synth is powered up. But even though inrush is only a problem in the first 100 or so msec when a circuit is powered up, that's all it takes for a catastrophic P/S failure. Also, the higher you can spec your P/S, the better, since a power supply under a heavy load is going to have more component issues due to thermal factors than one that's loafing along. A supply that can output 3A per rail or better will last a lot longer under a 1.5A load than one that only outputs 1.6.

Understood and thanks to both of you for the clear explanation! I wouldn´t like to burn more hp by adding a second PSU, so it´s either a beefier one or something completely external. I didn´t find too many module-based PSUs that offer substantially more power then the Arturia version (granted, at least they come in 4hp). Those torroidal transformers found in bigger cases come to mind,as they might allow for two smaller cases to be powered from a single PSU.

But I´ll give the cheapest option a go first, maybe I can rearrange modules and get around limits.

The Noise Engineering module can be powered from an alternative power bus. Check the manual. There's a DIP switch on the back to do this. Maybe that will be enough to get everything to play nicely.