Case Wiring, two Meanwell RT-65B

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TheSlowGrowth
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Post by TheSlowGrowth » Fri Jan 18, 2019 6:33 pm

Joker Domino wrote:Can I simplify it and run all the PSU COM and busboard GNDs to Earth distribution A and therefor discard B?
I wouldn't do it. As I said before, the point is to keep the noisy current from the mains filters away from your signal reference (which in your wiring schematic would be point B).
At the end of the day, I would not expect anyone to ever really notice the difference. For the relatively short wires and the high signal levels in a modular system, most of what we discuss here is pretty academic and it's not a serious issue if you do it wrong. So I guess, it would probably work either way. But every little reduction in noise levels will be a good thing, so why make it worse just to save a few cents on the wires? If you go through the effort of doing your own wiring, then do it properly - even if it is only for the peace of mind.

EDIT: Your wiring schematic looks perfectly fine to me. IMO you'll be doing all the important things right so I'd say, go ahead and build it and enjoy making music - that's what it's all about after all

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Post by ProgRocket » Fri Jan 18, 2019 8:10 pm

If you're faster than me, please report if the PSU are squealing without a minimum 5V load or not. I'd gladly take this heat source out.

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Post by Joker Domino » Sat Jan 19, 2019 5:28 am

Hi, I've done a little DIY Euro before and from my experience the PSU's do have a subtle 'ring' but this goes as soon as you add a unit.

It's not worried me before and don't think it will this time either. Easy to add after the fact too if so desired.


Best,

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Post by donturner » Sat Apr 13, 2019 4:21 pm

Just wondering how this build is progressing. I'm building the same thing, except with only 1 meanwell rt-65b and 2 busboards.

I'm particularly interested in how you've done the internal wiring e.g. did you hotglue the busboards, wago connectors and wires to the case?

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Graham Hinton
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Post by Graham Hinton » Tue Apr 23, 2019 10:12 am

Joker Domino wrote:Looking at the Doepfer and others they seem to just use a simple Earth > PSU and then run the PSU COMs to the busboard's GND...

This setup is obviously ok
This setup is NOT OK and blindly copying an incorrect system on a "monkey see, monkey do" basis is not going to yield good results. It means that the 0V reference for the busboard comes via a cable carrying >1A of current (and consequential voltage drop) and a pcb trace on the PSU--maybe.
It also would not pass a safety test where 4A or 25A is passed between a jack bushing and the mains Earth and needs <50milliohms to pass.

When you see a "ground" connection on a PSU is often just a Frame Ground (FG) and only connects to the PSU cover for safety.

If you have a bipolar PSU with a "COM" terminal it will be is carrying the difference between the positive and negative currents and that varies dynamically with module usage. If you Earth that point as a reference the "GNDs" on the busboards are going to be moving about with respect to that voltage. The correct way is to have the power regulators floating and preferably with separate +ve and -ve terminals and connect Earth to the 0V on the distribution. This is then the reference point that everything else is relative to and separate from safety paths.

It is not helpful to talk about noise as if it only exists in certain paths. All unwanted signals are noise and some of it is legit module operation. The trick is to make sure that there are separate paths of suitable resistance for each type and that they do not interfere with each other. It helps to quantify these currents to put it all in perspective.

funkytransport
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wooden case

Post by funkytransport » Thu Jul 18, 2019 5:31 am

How does this change if using a wooden case? if at all?

ProgRocket
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9U/12U eurorack DIY case with two Meanwell RT-65B

Post by ProgRocket » Tue Oct 08, 2019 6:01 pm

Hello,
djs, TheSlowGrowth and Mungo, you wonderful people! I did it! I finished in about three long weekends. My neighbor (electrician) tested it and gave me the go ahead. It works beautifully! Thank you guys so much.

Image Image Image
Image Image Image
Image Image


The 2.5mm squared wire is very stiff and gave me headaches. Also fitting several ring terminals in between the Meanwell terminals was a problem. It was easier to work with those orange clamps as distributor-blocks. ("WAGO 221" if anyone is wondering)

I built a 5V silent(!) fan with dust filter into it to safeguard against heat accumulation and all stays mildly warm.

If i were to do it again i would not do the compartmentalized version with 3 skiffs and instead do an all encompassing aluminum casing for more room inside. I thought i'd make it "modular" and swap skiffs in and out - but the cabling is too stiff for that.

Was it worth it? I am proud. But it also took a lot of time to figure out all the parts and requirements. Total cost was around 550€ (make it 480€ plus all the errors i made and minus the shipping of parts), so it was as expensive. If if i were to add another 30€, i could put another row of 3U on top.

Here are the assorted project files and cutting templates as .PDF and InDesign .indd files:
https://drive.google.com/file/d/1F-Oc9d ... sp=sharing

Again the 3D models for the snuggly Meanwell Terminator covers on Thingyverse/Tinkercad:
https://www.thingiverse.com/thing:3309423
https://www.tinkercad.com/things/g3FBf97guWa

Thanks again. I would buy you all a drink or two!
Cheers

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Post by Leverkusen » Sat Oct 26, 2019 5:28 am

Hey all!

I followed the discussion and all the advices of this thread an built a quite similiar setup with five rows and two PSU's - a linear Bell 3.4A and a switching Doepfer PSU3 2/1.2A.
The Bell is connected to three of the distro boards, the PSU3 to the other two boards. 0V are star wired as pictured above.

Now I am in the situation that three modules that have to be connected to the Bell PSU for structural reasons need 5V. I have always used the little Make Noise 5V adaptor for that in my previous smaller cases, but also the PSU3 provides 4A of 5V, that I do not need otherwise in the case.

I don't see a reason for not connecting the PSU3 5V supply to a board that gets its 12V from the Bell PSU - or am I overseeing something here? It would be slightly more efficient this way. At least unless it is a stupid idea and would lead to strange issues.

Does someone with more insight than me see any objections?

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Post by Graham Hinton » Sat Oct 26, 2019 6:29 am

Leverkusen wrote:The Bell is connected to three of the distro boards, the PSU3 to the other two boards. 0V are star wired as pictured above.
That is too vague a description. If there is a good 0V connection between boards it does not matter which PSU the voltages come from as long as you do not connect two +12Vs or -12Vs together. That's a bit vague too, by "good" I mean a really low resistance, lower than two of your 0V star wires.

The best way to achieve that is to run a busbar close to each board or mount all the boards on an aluminium plate, insulated from any case metalwork. Connect each board's 0V to that, connect the PSU Coms to that and connect the mains Earth to that.

Here's how to connect two or more PSUs together and to other cases:

Image

This shows all the different Earth and 0V resistances involved. The aim is to make the 0V path between any two modules as low as possible. The thick blue lines represent very low (<1mΩ) paths for which I would use busbars, but you can consider them for busboards too. It's just that busboards are not that low and when you have more than one it is difficult to get the 0Vs at the same potential.

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Leverkusen
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Post by Leverkusen » Mon Oct 28, 2019 3:28 am

Thank you for the advice, Graham! That's very helpful. I remember seeing that scheme before and I think that is basically what I did.

Though it does not work as good as expected but I am not sure if this is caused on the vague "goodness" of the 0V connections you mentioned.

Admittedly I just used a bit stiffer 1.5mm cables for the 0V star and Wago-like plug in connectors, which surely is not great but what I had lying around. My hope was that it should work, fits my actual budget and in case of noise issues and depending on their degree of severity I would have to rebuilt it proper later.

What I am experiencing now is that the linear PSU does not start up on the +12V line reliably. It got better by reducing the load through shifting two or three of the modules to the other PSU. But still sometimes one or two of the digital modules would simply not start on power cycling and very rarely the whole +12V fails.

I only use about 2.4A of the 3.4A the PSU is rated for on the +12V line. Now I wonder if this behavior could be caused by the not so perfect 0V wiring? Or is it still not far enough below the officially provided output current for a linear PSU?

I would have thought when everything is wired up electrically correct, the difficulties to get all busboards to the same 0V potential should not lead to big variances in voltage or current or cause major working issues, should they?

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Post by Graham Hinton » Mon Oct 28, 2019 8:56 am

Leverkusen wrote:Though it does not work as good as expected but I am not sure if this is caused on the vague "goodness" of the 0V connections you mentioned.
It is difficult to comment on what you may or may not have done unless you post a picture.
What I am experiencing now is that the linear PSU does not start up on the +12V line reliably. It got better by reducing the load through shifting two or three of the modules to the other PSU. But still sometimes one or two of the digital modules would simply not start on power cycling and very rarely the whole +12V fails.
Does the rail actually get to +12V? Have you got a scope to see how long it takes to rise?

Digital modules containing MCUs/DSPs might not have a robust power up reset.
I only use about 2.4A of the 3.4A the PSU is rated for on the +12V line. Now I wonder if this behavior could be caused by the not so perfect 0V wiring? Or is it still not far enough below the officially provided output current for a linear PSU?
You probably have a mistake, have you got a connection form the PSU Com(s) to the distribution 0V?
A 3.4A PSU should be able to deliver 3.4A otherwise it is not a 3.4A PSU. It is only when you try to draw more current that it will shut down.

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Leverkusen
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Post by Leverkusen » Mon Nov 04, 2019 7:57 am

Graham Hinton wrote: You probably have a mistake, have you got a connection form the PSU Com(s) to the distribution 0V?
A 3.4A PSU should be able to deliver 3.4A otherwise it is not a 3.4A PSU. It is only when you try to draw more current that it will shut down.
Thanks again, Graham! Of course you were right - even after double checking there is always one module left plugged in backwards. Especially after constantly taking everything out and putting back in while seeking for the fault. Now it works, no harm was caused and the upgrade to the Doepfer PSU gave me some more headroom at least.

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Post by LektroiD » Mon Nov 04, 2019 12:49 pm

I'm running two PSU's in my system. When it comes to wiring your modules, separate oscillators and filters to one PSU, and LFO's & modulation sources to the other... You'll save yourself the headache of LFO / modulation pulldown on your oscillators & filters.

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Post by bengarland » Mon Nov 11, 2019 9:21 pm

I've been reading / skimming this whole thread because I've gotten to the point where I need to upgrade the power for my 336 HP and I ordered two of the RT-65B to get started.

However, I'm kinda stuck because I don't have an earth ground on any of my outlets (well okay there's one for the laundry machine downstairs, but that's it for the entire apartment) -- it's just not common for even relatively new construction to have grounded outlets here in Japan, which sucks, but it's what I have to deal with.

So... given that all of the schematics and discussion posted so far in this thread seem to indicate a great importance of having earth ground when wiring a RT-65B to power a modular system, is there anything that I truly need to be worried about if I just wire it up as described and omit all of the lines that go to earth ground? Or do I need to have some of the ground lines between the equipment connected, just with no final ground line going to the wall outlet?

Anyone care to help? I'd really like to be able to do it without having to run a ground wire through my apartment and upstairs from the washing machine... it's a really far distance... though if someone can make a really, really good argument for doing so I will consider it. So far everything else in my studio has been fine without it since all of the equipment is 2-prong anyway.

Thanks!

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Post by Graham Hinton » Tue Nov 12, 2019 7:49 am

bengarland wrote: However, I'm kinda stuck because I don't have an earth ground on any of my outlets (well okay there's one for the laundry machine downstairs, but that's it for the entire apartment) -- it's just not common for even relatively new construction to have grounded outlets here in Japan, which sucks, but it's what I have to deal with.

So... given that all of the schematics and discussion posted so far in this thread seem to indicate a great importance of having earth ground when wiring a RT-65B to power a modular system, is there anything that I truly need to be worried about if I just wire it up as described and omit all of the lines that go to earth ground? Or do I need to have some of the ground lines between the equipment connected, just with no final ground line going to the wall outlet?
DO NOT attempt to add your own Earth wiring. That is a job for a qualified electrician and must meet your national regulations. If you are building a studio you should have a proper studio power installation. There is a lot of audio equipment on the international market that must be earthed and running it without an earth is unsafe.

Do not get confused by the connection to an actual Earth rod. The safety feature of having a mains Earth is due to it being connected to Neutral at your fuse or breaker board. It thus provides an alternative return path for Live and if that path is taken, due to a fault, a fuse or trip will blow. If you are working without a safety Earth you should have an RCD on your house and on your equipment mains distribution. These detect more than 30mA difference between Live and Neutral which means that Live is going somewhere it shouldn't so it trips.

I suggest that you contact the technical staff at a local studio and discuss what they have done. Having no safety Earth will work until there is a fault, then as everything is connected together the entire system will become unsafe. Two pin appliances are designed so that you cannot touch any part that may become live if there is an internal fault, but that does not apply to patchable synthesizers where you hold the patch cables and are in direct contact with the circuitry.

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bengarland
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Post by bengarland » Tue Nov 12, 2019 9:46 pm

Thanks Graham, I appreciate the additional info. I have a few comments, mainly due to my ignorance, and also to try to clear up my situation.

"There is a lot of audio equipment on the international market that must be earthed and running it without an earth is unsafe."

Agreed. However, I have bought most of my equipment here in Japan so it's all 2-prong... even the equipment that I think might have 3-prong elsewhere, like my Orange guitar amp. I have no 3-to-2 prong adapters. So wiring up modular power using these MeanWell units is the first time I've run into the grounding issue -- previously my rack was powered from the wall via a 2-prong AC-AC 12v wall wart adapter to a power board that then converted this 12V AC into +/- 12V DC.

"If you are working without a safety Earth you should have an RCD on your house and on your equipment mains distribution. These detect more than 30mA difference between Live and Neutral which means that Live is going somewhere it shouldn't so it trips."

If I understand correctly, RCD is the same as GFCI?

Given that I realistically can't have an electrician come in and run new ground wiring since it's a rental apartment, is there some way for me to get similar ground protection by using something like this:



It's described as an Earth Leakage Breaker -- 100V / 15A -- Rated Sensitivity 15 mA, Rated Operating Current 7.5mA

I mean, is this better than nothing at all?

And going back to my original question, if I'm dealing with a 100V AC 2-prong input situation (potentially with the aforementioned "Earth Leakage Breaker") what's the correct (or least bad?) way to wire everything, compared to the schematics posted previously in this thread which are for a 3-prong grounded input?

Assuming that I take the proper precautions to make sure that everything on the high-voltage AC side of the MeanWell isn't touching anything it's not supposed to.

Thanks again.

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Post by Graham Hinton » Wed Nov 13, 2019 3:12 pm

bengarland wrote:I have bought most of my equipment here in Japan so it's all 2-prong... even the equipment that I think might have 3-prong elsewhere, like my Orange guitar amp.
I was referring to equipment that has IEC inlets and a notice that says "This equipment must be earthed". If someone is selling those with IEC to 2-prong leads that is as dangerous as replacing a fuse with chicken wire. You would have no protection.
Do you mean equipment that has captive mains leads installed by the manufacturer?
I have no 3-to-2 prong adapters.
Good. They are not a solution.
So wiring up modular power using these MeanWell units is the first time I've run into the grounding issue
The purpose of the internal "frame ground" is so that if/when the PSU develops a mains fault that touches the cover it will blow a mains fuse immediately alerting you to the fact that it needs repair or replacement. That isn't completely foolproof, but it covers what the manufacturer expects might happen.

If you don't Earth the frame ground it might be sitting there faulty and catch fire or you may touch it and you won't find out until that happens, which may be too late.

If I understand correctly, RCD is the same as GFCI?


Yes, they trip when Live and Neutral differ by a small current.

It's described as an Earth Leakage Breaker -- 100V / 15A -- Rated Sensitivity 15 mA, Rated Operating Current 7.5mA

I mean, is this better than nothing at all?


Yes, but the difference between that and an earthed system is that the RCD only trips when the fault current happens and that may be caused by you touching it. You will still receive a shock, but it will be turned off fairly quickly. -ish. As long as the mains is coming from something powered on that breaker, if it were coming from elsewhere, say a dangling patchcable touches a frayed mains wire on another outlet, then sorry, game over.

Those devices have a test button, but all that tests is the trip. A real test would be to connect your equipment to mains live and then touch it and see if you only get a non-lethal shock. Fancy doing that?!

And going back to my original question, if I'm dealing with a 100V AC 2-prong input situation (potentially with the aforementioned "Earth Leakage Breaker") what's the correct (or least bad?) way to wire everything, compared to the schematics posted previously in this thread which are for a 3-prong grounded input?


The correct way of building non-earthed equipment is to double insulate all the circuitry. That means that you will have to invent a jack connector with a safety shroud. In other words you can't convert one to the other, double insulated appliances are designed from scratch and tested before being put on the market and you don't build an audio studio out of double insulated appliances.

Sorry, that's not the answer you want. I can only try to impress on you why you should not be cavalier about this.

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Re: Case Wiring, two Meanwell RT-65B

Post by ADV » Tue Feb 11, 2020 12:10 pm

I'm really glad I came across this thread. So I'm in the process of building a 13u 168hp case. I will be making it out of wood. I need a lot of power as I want to put some Behringer synths in the rack also being I use them with my modular most of the time. I was looking at this power solution thinking it was pretty simple and straight forward. After reading through this thread and seeing these diagrams I'm not feeling very confident. In the final diagram i see ground going to the chassis. Am I correct in assuming I don't need to do that being my case is wood? any guidance would be much appreciated. The other 2 options I was looking at were Trogotronic and Synthrotek. I'm not sure how I feel about the Trogotronic with having power bricks in the case and Synthrotek Super Power Blue x 2 will be over $600. Below are my power requirements via Modular Grid. Thanks in advance for any help!


Power Consumption: 4755 mA +12V | 774 mA -12V | 205 mA 5V

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