#193

good Morning,

I apologize if my post has been covered by other posts. I am afflicted with ignorance when it comes to Electricity despite my long-standing use of electronic instruments.

Recently, I acquired a very awesome eurorack case with a Doepfer A-100PSU2 inside. Nice. But it will only run a couple modules at a time. Lame. I used a multi-meter tool to measure the VOLTS and saw 12v and -12v on the meter so the power is there.

When I plug in too many modules, they simply fail to power on. I am not running any 5v modules as I do not believe this power supply supports 5v modules.

Any ideas of how to fix this PSU or have I encountered a lost cause?

#194

It could be a power header on the supply, a cable or a module…I’d say first do things 1 by 1 eliminating variables to see if it’s one of those things. As a side note, make sure to turn the system off plug things in and turn back on. Euro power is not hotpluggable

#195

How many modules are you running? What is the current draw of the modules? Without that information, it’s hard to give any clear advice.

#196

If you have your modules in modulargrid you should be able to see how many amps those modules need. Your power supply looks like it can supply 1200mA on the 12V and -12V rails but if there is an external brick supplying power to it you should make sure that it can also supply the appropriate amount of amps. So the total amps that your modules draw should be less than I think it was like 80% of the amps of your power supply if I remember correctly.

#197

In regards to busbars I use one for all my grounds. I’ve got busboards in there to make hooking modules up easy but I still tie off all my grounds to a single bar. I suppose my thought was I could have stars in my stars in regards to grounding and I haven’t ran into any issues using two metatronic mods PSUs. Btw, metatronic mods has a wild busbar distroboard solution but I’m using their older style busboards.

#198

Thank you for your thoughts on my power supply dilemma, fellows.

I only have five modules plugged in; the current draw is very small: 324 mA +12V | 188 mA -12V

No power brick, just a large cord.

I have never plugged a eurorack module in with the case power on due to Fear.

All the modules which have failed to power on in this case work just fine in a Mantis case.

#199

That certainly seems like something is awry.
The PSU2 is the one with the toroidal transformer IIRC.
Are you using the case in a different country to its origin?
Take some photos of the info on the transformer and some board photos. Also check the fuses.

#200

I’m in the U.S. and the case came from New Jersey. Not sure where it was before that, if anywhere.

Here are photos of the top & bottom boards as well as the PSU. Not sure if they’re useful in any way.

The seller did include some extra fuses. Do you happen to know where I ought to look for them in the case?

Thanks much.

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#201

Thanks for the photos.
The transformer is unmarked so that’s generally a sign of it being the 115v version, which is correct. The rectifier must be working, and the caps seem fine. Perhaps there’s an issue with the regulators that are under the heatsinks, but that’s conjecture.
The busboards shouldn’t be an issue either, although one of the pins is bent on the -12v side (visible in your second photo) so be careful of that.
The fuse is in the power socket - you can pull out a tray between the on switch and the three-pin socket. It should be an 800ma slow-blow fuse (it will have a “T” marked on it)
You can see this info on page 4 of this pdf:
http://www.doepfer.de/a100_man/A100_short_form_manual.pdf
If you don’t mind, please take a photo of the wiring both to the busboards and to the power switch. Please unplug it from the mains so there’s no live voltage to zap you!
Actually, I’d also visually inspect the pins on the busboards - as one pin is visibly bent, there may be others that are in a riskier position, such as touching each other etc.
Also, when the case is powered up without modules, do the LEDs light on both the PSU board and the busboards?

#202

hello, You’re the best, thanks so much for taking the time to think about this with me.

I replaced the fuse (dubious solution) and straightened all bent pins.

I removed all the modules from the case and observed the lights turn on both on the power supply and boards.

I replaced the modules one by one until, in a blaze of solar light, adding a module caused all the modules to not power on.

I moved that module to a different header and everything works OK now.

So, probably a few bad headers in there, which is OK because there are way more than I could feasibly use.

Thanks again.

1 Like
#203

You’re welcome!
From a robustness point of view, I’d definitely take out that busboard so you can inspect the reverse for any cold solder joints etc, especially where you were seeing problems.
You could also try continuity testing the boards to see if there are any broken traces between headers.

1 Like
#204

So, I’m trying to install a power supply unit and a bus board into my eurorack case. But the instructions are kind of vague, and I’m a noob. So I wonder:

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  1. I want to connect the power inlet cables (black +, white -) into the input terminals on the PSU. But there are two + inputs and two - inputs. Does it matter which ones I use?
  2. I want to connect the PSU to the bus board (gnd to gnd, +12v to +12v, etc). But do I really need to connect the +5v cable when my system doesn’t need that?
  3. The bus board has two sets of terminals. Does it matter which one I use? Should I use both?

Thanks!

#205

Are the power inlets from a wall outlet (i.e the board has a transformer) or a lower voltage AC or DC supply? In the former case the two wires are potentially to allow you to use two lower gauge wires. In the latter case (for an external DC supply) it may be to connect two up at once (to double the available current). In the latter case you can connect to either terminal, as long as you get +ve and -ve correct.

As for connecting up the 5V, I can’t see why you wouldn’t: it’s trivial and the day you try a module that needs a 5V supply, you’ll end up less confused about why it’s not working. Modules can exhibit very strange behaviour when partially powered, so I’d just connect it up.

I presume the two sets of terminals on the bus board are to allow easy connection from a supply whichever side you mount it on (though you could theoretically connect two power supplies to a single board): I’d only wire up the closest one.

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#206

The PSU is powered via a power adaptor (18V, 60W, Mean Well GSM60A18-P1J). I suppose that would be “a lower voltage” in your example, and I can connect to either terminal.

Thank you so much! Your answers were very helpful! I’ve never done this before, and want to make sure I don’t accidentally destroy my modules! :slight_smile:

#207

A final question. I’ve now connected everything, but the LED’s on the bus board shine red. I would expect them to be green if everything is OK.

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I’m using this bus board: https://modularsynthlab.com/product/eurorack-bus-board-msl-filter-bus-board/ But there is no information on colors of LEDs as far as I can see.

I use the recommended power adaptor. I’ve connected power inlet cables to PSU (+ to +, and - to -). And I’ve connected PSU to bus board (gnd to gnd, +12 to +12, etc).

Do I dare to connect a module to see if it works?

#208

Well, I suppose you might want to try using a multimeter on some of the power headers first before frying some of your modules in case you’re unsure about your connections. I would even be tempted to recommend checking with a multimeter even if you’re sure about what you are doing. That way you just make double sure that everything went well and without any costly confusions.

As for the LEDs: they might as well be red ones. Many bus boards are actually using red LEDs. It’s not necessarily the colour which counts but that they are lit evenly and at all…

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#209

Good idea, I’ll do that, thanks! :slight_smile:

#210

Agreed: considering that the only power provided to the bus board is from the power supply, it would be significantly more complex to provide “power inspection features” (since powering the board incorrectly wouldn’t allow such features to operate) beyond the power indicator LEDs. Instead these 3 LEDs, along with appropriate resistors, run between the three power lines and ground. The appropriate resistors mean you get the required current for maximum brightness for each LED. If the power is incorrect (e.g you swapped 5v and 12v or -12v and ground) one or more LEDs will be a noticeably different brightness to the others (brighter, dimmer or off). This won’t catch all possible problems, but it will catch you accidentally interchanging the power leads.

As was said: The best bet is to use a multimeter. Note: I recommend against testing directly on the headers (it’s very easy to short circuit things like this). Instead plug in a (ideally 16->16) power connector (like you’d connect a module to) and confirm the voltage of each pin reference to ground. Typically I do this in two steps, first I check for continuity between the 6 ground pins when unpowered. I then power the system and check the voltage between any ground point and all 6 power pins: the end two by the red stripe in the ribbon are -12V, the next 3 pairs from that end are ground, the next pair is +12V, the next +5V. The next two pairs won’t be connected to the power supply, so you can ignore them for these proposes. If the voltages are okay (including polarity), then you are good to go.

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#211

Thank you so much for your detailed answer! :slight_smile:

#212

Anybody knows where I can find these? They’re sold out everywhere and Malekko isn’t responding to the messages on their websites for a while now. I don’t even know if everything is good since the pandemic hit, hope they’re fine above all.

If anyone knows where or when these power supply will be available, I would appreciate it, been trying to get one since late 2019.