Meanwell Modules - AH ML5000 PSU Replacement

[Blissy]

That all sounds good but you need to get rid of the thermals. Thermals are the little spokes around each hole for a part that connect to the trace / plane. The help you solder. Without thermals all of that copper wicks away the heat of your soldering iron and prevents the solder from flowing into the joint properly. But in this case you really need that copper. It doesn't really matter if you have giant traces if they then turn into 4 little spokes to get to the bus wire of the part. That's like making a 4 lane interstate highway that turns into a bicycle path for 100 feet. So I would dig around in your layout software and figure out how to turn those off. It will make them hard to solder. If the solder doesn't flow into the joint properly, you will need to get a bigger soldering iron. Usually people have one cheapo thing from the 80's that's like 50 watts just for this sort of thing. But a flux pen and some patients might also be good enough.

Although, is there no way to lay all of the SMPS out flat? Or at least the two 17V and then put the 48V over the 12V. You can put them right up against the edge of the enclosure no problem. And the PCB can be mounted anywhere. Maybe make it long and narrow so that it can be mounted vertically would help?

Great! Thanks. Thought I had removed thermals need to do more digging in Kicad been a while.
Will see what I can do regarding layout should be able to the get larger modules to layout flat.

Thanks again
Blissy

 

[Blissy]

Updates made Thermals on High Current Tracks and Planes have been removed and Case layout adjusted.

https://drive.google.com/drive/folders/1Dp_4JAiCEoobhb72Us4U056dN83dUNpd?usp=sharing

Any recommendations regarding the 100Ohm resistor from AGND to DGND as on the original PSU schematic. 

 

[volker]

Something you might still have to watch is the widths of your traces. Take a look at this table: https://www.multi-circuit-boards.eu/en/pcb-design-aid/surface/conductor-ampacity.html

What it tells you is by how much is the temperature of the copper increasing at what current and trace width. Higher temperature of course reduces general reliability, constant overload leads to eventual failure. You're in Australia, so your temperature environment is probably rather warm. Just think about it, 50° is already so hot it would hurt to touch. Also, toasted FR4 is something to be avoided.

 

[Blissy]

Something you might still have to watch is the widths of your traces. Take a look at this table: https://www.multi-circuit-boards.eu/en/pcb-design-aid/surface/conductor-ampacity.html

What it tells you is by how much is the temperature of the copper increasing at what current and trace width. Higher temperature of course reduces general reliability, constant overload leads to eventual failure. You're in Australia, so your temperature environment is probably rather warm. Just think about it, 50° is already so hot it would hurt to touch. Also, toasted FR4 is something to be avoided.

Interesting, I have looked at a number of these design aids. I was also planning to use 2oz copper.
I guess there is no harm in making the traces are large as I can! shall update

Thanks volker 

 

[Blissy]

https://drive.google.com/drive/folders/1Dp_4JAiCEoobhb72Us4U056dN83dUNpd?usp=sharing

Updated. 7mm Traces on +17 -17 and +12 and mounting holes added. looking to order parts and send away for boards to get manufactured soon.

I have been looking into the separation between the AGND and DGND and consensus seems not to bother, Please inform me if I am wrong. Any Final advice would be apricated before moving forward

Thanks
Blissy 

 

[Bo Deadly]

Stop the presses! There is a huge error.

You connected mains neutral to GND. You need to create a separate ground plane for mains neutral.

 

[Blissy]

Stop the presses! There is a huge error.

You connected mains neutral to GND. You need to create a separate ground plane for mains neutral.

Press Halted! As In CONX 9 Mains Earth that is currently connected to the Ground Plane ?

 

[Bo Deadly]

All of your mains neutral feeds are connected to GND which is connected to mains earth which, aside from being bad on it's own, is defeating the isolation of the SMPS. It probably wouldn't burst into flames but everything will sound like it was recorded in the engine room of an oil tanker. Look at my schematic. Mains neutral is NOT connected to GND.

 

[Blissy]

All of your mains neutral feeds are connected to GND which is connected to mains earth which, aside from being bad on it's own, is defeating the isolation of the SMPS. It probably wouldn't burst into flames but everything will sound like it was recorded in the engine room of an oil tanker. Look at my schematic. Mains neutral is NOT connected to GND.

Sorry if I am being stupid here, By "Mains Neutral" are you referring to the Negatives (V-) of the meanwell Modules as in CONX 2,3,6,8 as There is no direct connection to mains on the PCB apart from currently the Earth Chassis (which is tied to neutral at switch board). (conx9)

 

[Bo Deadly]

Sorry if I am being stupid here, By "Mains Neutral" are you referring to the Negatives (V-) of the meanwell Modules as in CONX 2,3,6,8 as There is no direct connection to mains on the PCB apart from currently the Earth Chassis (which is tied to neutral at switch board). (conx9)

Never mind. You're circuit is fine. I'm being stupid. False alarm.

So presumably all of your mains connections are connected together somewhere else using a terminal strip or something?

That's fine. Carry on.

 

[Blissy]

Never mind. You're circuit is fine. I'm being stupid. False alarm.

So presumably all of your mains connections are connected together somewhere else using a terminal strip or something?

That's fine. Carry on.

No Stress ! Correct, that is the plan.
Thanks again

Cheers Blissy

 

[abbey road d enfer]

Any recommendations regarding the 100Ohm resistor from AGND to DGND as on the original PSU schematic.

Its only purpose is to make sure the different rails have a similar reference when the PSU is not connected. If it wasn't there, there could be a significant voltage between them and that may be damageable when connecting the PSU to the mixer. So I would retain it. In operation it does nothing.

 

[Blissy]

Its only purpose is to make sure the different rails have a similar reference when the PSU is not connected. If it wasn't there, there could be a significant voltage between them and that may be damageable when connecting the PSU to the mixer. So I would retain it. In operation it does nothing.

Thanks  abbey road d enfer, So would you recommend adding a seperate ground plane for the 12v Digital supply with a resistor to GND ? Currently they all share the same plane

 

[abbey road d enfer]

Thanks  abbey road d enfer, So would you recommend adding a seperate ground plane for the 12v Digital supply with a resistor to GND ? Currently they all share the same plane

I would do that anyway. It makes sure there is no cross-pollution, and you can choose exactly where you want to join the "grounds".

 

[Blissy]

I would do that anyway. It makes sure there is no cross-pollution, and you can choose exactly where you want to join the "grounds".

Ok I have Updated the PCB layout and schematic to include a separate ground plane for the +12v DGND. With a 100 Ohm Resistor that connect the two together.

https://drive.google.com/drive/folders/1Dp_4JAiCEoobhb72Us4U056dN83dUNpd?usp=sharing

Cheers
Blissy 

 

[Bo Deadly]

I would do that anyway. It makes sure there is no cross-pollution, and you can choose exactly where you want to join the "grounds".

If the two grounds share the same ground plane they cannot be at different potentials when the connector is disconnected. So clearly the 100R is just an attempt to isolate AGND from DGND.

I were designing a supply from scratch I would not think to put it in there because there might be places where DGND is used to reference analog signals such as comparators driving LEDs for VU meters in which case the 100R could cause small albeit probably insignificant jumps in ground differential as digital stuff is switched on / off. Meaning an LED in a VU meter might flicker when you switch a bank of relays for example.

Also, now DGND is not connected directly to earth? Is that okay? What is the size of this 100R? If there's a short and a bunch of current gets dumped into DGND, is that little 100R going to pop and generally cause unfortunate things to happen?

Although I guess if it was in the original circuit I would be inclined to retain it. It is a fundamental part of the interface defined by the design of the original supply. It cannot perform worse than the original supply.

 

[Blissy]

If the two grounds share the same ground plane they cannot be at different potentials when the connector is disconnected. So clearly the 100R is just an attempt to isolate AGND from DGND.

I were designing a supply from scratch I would not think to put it in there because there might be places where DGND is used to reference analog signals such as comparators driving LEDs for VU meters in which case the 100R could cause small albeit probably insignificant jumps in ground differential as digital stuff is switched on / off. Meaning an LED in a VU meter might flicker when you switch a bank of relays for example.

Also, now DGND is not connected directly to earth? Is that okay? What is the size of this 100R? If there's a short and a bunch of current gets dumped into DGND, is that little 100R going to pop and generally cause unfortunate things to happen?

Although I guess if it was in the original circuit I would be inclined to retain it. It is a fundamental part of the interface defined by the design of the original supply. It cannot perform worse than the original supply.

Thanks Squarewave, I also Share these concerns, However I can confirm it is a part of the original Supply Schematic. I measure 100 ohms from AGND to DGND and 100 Ohm from DGND to Chassis / Mains Earth. The resistor is only a standard 1/4 Watt on the original.

I could include a way to Bypass this resistor adding the option to Link the two planes together at multiple Points.

 

[Bo Deadly]

Thanks Squarewave, I also Share these concerns, However I can confirm it is a part of the original Supply Schematic. I measure 100 ohms from AGND to DGND and 100 Ohm from DGND to Chassis / Mains Earth. The resistor is only a standard 1/4 Watt on the original.

I could include a way to Bypass this resistor adding the option to Link the two planes together at multiple Points.

Sounds good. For the sake of consistency I updated my "schematic" to include isolated AGND / DGND.

Incidentally, why not use LRS-35-48 for 48V? The 75W one seems a little unnecessarily large.

 

[Blissy]

Sounds good. For the sake of consistency I updated my "schematic" to include isolated AGND / DGND.

Incidentally, why not use LRS-35-48 for 48V? The 75W one seems a little unnecessarily large.

Great, Thanks Squarewave. I have just updated the drive with the latest revisions. Any final advice for before sending away for manufacturing.
Will do re LRS-35-48 Cheers ! 

https://drive.google.com/drive/folders/1Dp_4JAiCEoobhb72Us4U056dN83dUNpd?usp=sharing

Cheers
Blissy

 

[Bo Deadly]

Looks fine to me. Of course I haven't scrutinized it like I might one of my own designs but I can never seems to make a PCB that's 100% perfect the first time anyway. But I always make it work anyway. So I would say roll with that.