Meanwell PSU wiring question

CLee · Post by **CLee** » Tue Nov 01, 2016 7:18 am

Sort of puts a dent in the advantage of a switching supply. Switchers are more energy efficient, but you're burning away half an amp of current just to keep the 5v supply in spec.

ray · Post by **ray** » Tue Nov 01, 2016 7:27 am

Maybe i just add a Module which uses the 5v. Would be nice if these were Listed but afaik modulargrid only lists the usage of the modules in your rack.
Edit
ps: found a list:
viewtopic.php?t=73617

Sinamsis · Post by **Sinamsis** » Sat Dec 17, 2016 8:53 pm

acilator wrote:I'm trying to figure out how to connect multiple PSU (Meanwell RD-3513) in one case (175 hp, 5 row). The drawing below shows how I think it needs to be done, after a lot of reading here on the forum and on de the Dutch synthforum, can somebody please check this and confirm or this is the wright way to go, or please give me some tips how it's better..

Doing a little necromancy here, sorry..... but I'm in a similar predicament. Out of curiosity, in this diagram (which I plan on using for my case, thanks dude!), what are you using for the common ground/ground distribution? Would something like this work?

flab · Post by **flab** » Wed May 31, 2017 6:07 am

i know is an old thread , though because i think i will blow thinks up. two questions

i do own a meanwell 65B

one; i get a high pitch sound when is on, the pirtch changes as i adjust the trimmer.

two; there is no 12V output + or- ; is more like ~15 +/-

three; the COM is shorted with 5V is that normal(is shorted even when there is nth connected to the power supply)?

sounds like a short . i know,

Altitude909 · Post by **Altitude909** » Wed May 31, 2017 6:42 am

>one; i get a high pitch sound when is on, the pirtch changes as i adjust the trimmer.

They sing with no load

>two; there is no 12V output + or- ; is more like ~15 +/-

You sure its a B and not a C? Could be a no-load issue as well

>three; the COM is shorted with 5V is that normal(is shorted even when there is nth connected to the power supply)?

That seems off but I'll pass on that question

flab · Post by **flab** » Thu Jun 01, 2017 6:12 am

any other eanwell users , explain me how and why the 5v outputs is shorted with COM, is the same in both of my power units

thanks again

flts · Post by **flts** » Thu Jun 01, 2017 6:22 am

flab wrote:any other eanwell users , explain me how and why the 5v outputs is shorted with COM, is the same in both of my power units

By "shorted" do you mean "when measuring resistance between COM and +5V, it is 0 ohms or almost 0 ohms"?

I'm asking this because the "continuity" function in many multimeters beeps even if resistance is noticeably higher than 0 ohms (ie. not shorted, just low resistance).

flab · Post by **flab** » Thu Jun 01, 2017 6:48 am

hi fits is 32.5ohm

flab · Post by **flab** » Thu Jun 01, 2017 10:47 am

so i connected a module , the pitch sound is away, so altitude909 was correct, though the voltages are still high +13.8 and -14.8 even if i trimmed it all the way down. Do you connect your eurorack with those powers? i am not sure if all my modules wearing above 25 v components

flts · Post by **flts** » Thu Jun 01, 2017 11:52 am

flab wrote:though the voltages are still high +13.8 and -14.8 even if i trimmed it all the way down.

like altitude asked, are you sure it's RT-65B and not RT-65C? B is +-12V, C is +-15V.

i didn't actually know they were trimmable, only noted the +5V trimmer.

flab · Post by **flab** » Thu Jun 01, 2017 12:26 pm

I am yes

. Could be my mains at home crazy?my multimeter?

flab · Post by **flab** » Thu Jun 01, 2017 3:24 pm

ok guys i am embarrassed to say that all the voltage problem was related to a bad multimeter i have, all good for now, thank you guys

dhaillant · Post by **dhaillant** » Fri Jun 02, 2017 1:54 am

flab wrote:ok guys i am embarrassed to say that all the voltage problem was related to a bad multimeter i have, all good for now, thank you guys

That's where having 2 or 3 DMMs is important: you can monitor multiple readings at once (both rails for example), and moreover, you can get confidence in the accuracy of your readings, comparing your DMMs each others regularly.

lasesentaysiete · Post by **lasesentaysiete** » Tue Jul 11, 2017 2:20 am

Can I separate the distribution at the psu with the meanwell rt-50b, rather than daisychaining busboards?

I would like to distribute to 2 separate cases without having to have them both connected at once, necessarily. So with the rt-50b, I would have 2 separate distribution points connected to V3, V2, COM, respectively.

Also, how does the dummy load resistor for 5v get wired?

cygmu · Post by **cygmu** » Tue Jul 11, 2017 3:24 am

lasesentaysiete wrote:Can I separate the distribution at the psu with the meanwell rt-50b, rather than daisychaining busboards?

I would like to distribute to 2 separate cases without having to have them both connected at once, necessarily.

You can certainly do that, just by running cables from the PSU to the two cases separately. Then you are back to the arrangement in the Doepfer wiring diagram, which Graham Hinton has pointed out is not optimal: see this post upthread
viewtopic.php?p=2343715#2343715

lasesentaysiete · Post by **lasesentaysiete** » Tue Jul 11, 2017 3:36 am

cygmu

lasesentaysiete · Post by **lasesentaysiete** » Tue Jul 11, 2017 3:49 am

To follow up on my previous post:

The XLR connectors I have--I don't have enough experience with xlr to know if they're all like this or not--have a chassis ground pin. Therefore, the chassis ground can be carried all the way to the case and joined to the distribution board there. This seems, to me, to alleviate the long 0v cables problem, no?

ps, let's ignore the pros/cons of using xlrs for power

Graham Hinton · Post by **Graham Hinton** » Wed Jul 12, 2017 4:41 am

lasesentaysiete wrote:The XLR connectors I have--I don't have enough experience with xlr to know if they're all like this or not--have a chassis ground pin. Therefore, the chassis ground can be carried all the way to the case and joined to the distribution board there. This seems, to me, to alleviate the long 0v cables problem, no?

The purpose of the chassis pin on an XLR is so that the screen of a cable (on pin1 with audio cables) may be connected to the chassis in conformance of AES48 practise. If you have a Neutrik XLR the solder tag is right next to pin 1 for the shortest possible wire link connection because extending a cable screen within a screened enclosure may cause it to radiate RFI.

Chassis ground should be an enclosing screen that does not carry current apart from tiny radio frequency currents due to cables acting as aerials. It is not the signal 0V Common even though both are connected to mains Earth, the difference is what currents flow where. 0V should exist within Chassis Ground, but not use it as a path.

The only way to alleviate the 0V problem between two cases is to connect them together with a very low resistance. The engineering approach is: how much resistance is acceptable? then: how much metal is needed to implement that? That rules out XLRs and the limited gauges of cable that fit in them. Don't think that a run of one 14 gauge wire will be enough, a bundle might be for a short distance--like 1 ft.

This is only a problem because people with little or no electrical knowledge insist on building large unbalanced systems with unsuitable external power supplies. The problem does not exist in comparable systems, like a large studio outboard rack, so the obvious solution is to follow that paradigm.

seal_cobblr · Post by **seal_cobblr** » Wed Jul 12, 2017 7:55 am

Grounding and 0v aside, the mean well rt-50b is acceptable for at small system? or is a transformer +the mofos or cgs power supply circuit that much better?

Graham Hinton · Post by **Graham Hinton** » Wed Jul 12, 2017 8:52 am

seal_cobblr wrote:Grounding and 0v aside, the mean well rt-50b is acceptable for at small system?

When you see a PSU that has a large +5V and asymmetric +/-12V outputs it is intended for an application that involves a lot of logic circuitry controlling motors and solenoids with some analogue interfacing, e.g. a few comparators and RS422/232, not a quality audio system. There are lots of industrial applications like that, hence the availability of cheap OEM PSUs.

You can't put 0V and grounding aside, it is a fundamental requirement for any audio circuit, and any PSU with a single Common 0V output is going to have common impedance problems at higher currents, especially if you have a lot of digital modules whether they run on +12V or +5V.

"Acceptable" is relative to expectations and budget. If they are low, then volts are volts and amps are amps and you can use it if you don't mind all the cons.
All I can say about Meanwell is that I suppose they mean well...

wotwot · Post by **wotwot** » Fri Oct 27, 2017 6:19 pm

CLee wrote:Sort of puts a dent in the advantage of a switching supply. Switchers are more energy efficient, but you're burning away half an amp of current just to keep the 5v supply in spec.

Looking at the block diagram of the RT-65B, the only regulation sits on the 5V rail.
A (for some people) nicer way than loading the 5V rail with a big resistor is to connect a small incandescent lightbulb to it which will smoothly use its current (and as a side-effect illuminate the interior of the case).

mebitek · Post by **mebitek** » Wed Apr 18, 2018 1:37 am

Hi I have a problem with my make noise Rene, this should fix it?
Here how my meanwell psu is connected.

Someone can help me?
Thx

flts · Post by **flts** » Wed Apr 18, 2018 2:17 am

^- Currently you have a floating supply, the mains earth is not connected to 0V / COM at any point. The earth pin in Meanwell is just for the chassis of the supply (electrical safety), it isn't connected to COM internally.

According to my experience, Rene, Pressure Points etc. really require a path to ground to work in any sane way. So you need to tie the mains earth to the COM / 0V at some point - preferably running a GND wire to the point of distribution (or by jumping the GND to COM on the supply side if you absolutely can't do it in any other way for some reason).

I would also use proper thick wires from power supply to the power distribution if possible, that ribbon cable looks a bit scary.

Unless that ribbon cable IS the power distribution in which case I won't comment on that further and you'll most probably need to connect the GND and COM together on the power supply side.

mebitek · Post by **mebitek** » Wed Apr 18, 2018 2:22 am

flts wrote:^- Currently you have a floating supply, the mains earth is not connected to 0V / COM at any point. The earth pin in Meanwell is just for the chassis of the supply (electrical safety), it isn't connected to COM internally.

According to my experience, Rene, Pressure Points etc. really require a path to ground to work in any sane way. So you need to tie the mains earth to the COM / 0V at some point - preferably running a GND wire to the point of distribution (or by jumping the GND to COM on the supply side if you absolutely can't do it in any other way for some reason).

I would also use proper thick wires from power supply to the power distribution if possible, that ribbon cable looks a bit scary.

Unless that ribbon cable IS the power distribution in which case I won't comment on that further and you'll most probably need to connect the GND and COM together on the power supply side.

I'm really a newbie, thx for the clarification. So I need to connect ground to com with a wire? Can you please make me a picture or a schematic?

cretaceousear · Post by **cretaceousear** » Wed Apr 18, 2018 4:11 am

mebitek wrote:I'm really a newbie, thx for the clarification. So I need to connect ground to com with a wire? Can you please make me a picture or a schematic?

I'm not being a smart arse but if you read this thead from page one you will understand what needs doing - the important stuff is all there on page one. Mr Hinton's text is da bomb - that means it won't be an electro-bomb - sorry, pretending I'm a kid - it's the dog's bollocks, the acme of exactitude.

MUFF WIGGLER

MUFF WIGGLER

Meanwell PSU wiring question