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SE/30 - Design for Drop in Replacement Power Supply

dalek

Member
From what I can see the connector wires are soldered directly to the PCB, meaning over time there is a possibility of the wire breaking at the solder point.

A better solution if you are selling them would be to use crimp PCB terminal pins and solder those instead.
 

Compgeke

Well-known member
@mg.man - I probably won't be selling PCBs only. I do sympathize about the cost for international shipping, VAT, duties, etc., but I want to avoid selling anything that would resemble a 'kit'. There is a lot more 'customer support' in this situation, even if you state that no direct support is available. I prefer to sell a working and tested unit as that eliminates variables and excess communications.

Heads up this *may* not be the best idea from a legal standpoint. A complete PSU will very very likely need to go through a bunch of safety/compliance checks to sell in many countries. UL/TUV is not cheap. You'd be opening yourself up to a lot of liability if one were to somehow fail and cause "damage to people or properties" as organizations such as NFPA put it.

This is actually such a headache there're products you can get from big companies like Ryobi or Unifi that integrate an off-the-shelf power brick into the machine and plug into the boards. This gets around needing to have the stuff certified.
 

zigzagjoe

Well-known member
I'd be curious to see the details of the communications with meanwell regarding the common ground reference across the modules... I could envision some uses for those myself.

Also, just to verify, are you measuring voltages at the PSU, or at the logic board?

The reason I ask is it's typical to find with retrofits that the PSU is outputting a steady 5v, but due to voltage drop before hitting the LB, the LB only sees 4.8v (or worse) depending on cards installed. The stock PSUs allow you to adjust the output to mitigate, but usually modern units don't allow this. Replacing the 22ga 5v wires in the harness helps some, but it's more in the manner of reducing losses rather than bringing voltage back to a solid 5v.
 

(o';'o)

Member
From what I can see the connector wires are soldered directly to the PCB, meaning over time there is a possibility of the wire breaking at the solder point.

A better solution if you are selling them would be to use crimp PCB terminal pins and solder those instead.
The original PSUs did use the crimp terminal pins to solder to the PCB. I would argue that they are not necessary. Wire breakage has to do with repetitive movement over extended periods of time. The wire becomes work hardened with every movement, looses flexibility, becomes fragile, and eventually breaks. Direct soldering can exacerbate this condition.

However, in these power supplies and computers, vibration is nil. The PSU is installed once and effectively remains fixed and static for the duration of it's life. Soldering offers the best ohmic connection, reducing resistive voltage drops, thus improving load regulation. If I were designing for electronics to be taken on the go, installed in a car, bike, etc. I would certainly consider an a different attachment method.

-Chris
 

(o';'o)

Member
I'd be curious to see the details of the communications with meanwell regarding the common ground reference across the modules... I could envision some uses for those myself.

Also, just to verify, are you measuring voltages at the PSU, or at the logic board?

The reason I ask is it's typical to find with retrofits that the PSU is outputting a steady 5v, but due to voltage drop before hitting the LB, the LB only sees 4.8v (or worse) depending on cards installed. The stock PSUs allow you to adjust the output to mitigate, but usually modern units don't allow this. Replacing the 22ga 5v wires in the harness helps some, but it's more in the manner of reducing losses rather than bringing voltage back to a solid 5v.
I'm a big fan of the IRM series, and Mean Well in general. I've never encountered a bad module and they always perform as you expect. For your projects, I would suggest that you reach out to them directly. The correct contact email can be found on their website depending on the country you reside. My experience has been that the provide a response in 3-5 days.

@JdM74 has been my main contact for in-computer load testing. His communications to me were that the measurements were taken at the floppy connector (measurements posted earlier in this thread).
 

(o';'o)

Member
Heads up this *may* not be the best idea from a legal standpoint. A complete PSU will very very likely need to go through a bunch of safety/compliance checks to sell in many countries. UL/TUV is not cheap. You'd be opening yourself up to a lot of liability if one were to somehow fail and cause "damage to people or properties" as organizations such as NFPA put it.

This is actually such a headache there're products you can get from big companies like Ryobi or Unifi that integrate an off-the-shelf power brick into the machine and plug into the boards. This gets around needing to have the stuff certified.

There are risks and liabilities to be aware of when selling any product, and there are a number of ways to protect yourself and the customer.

First, I operate and make sales under my business, Baby Face Electronics LLC. This offers some base level of liability protection as a manufacturer and seller as it provides some separation of my business and personal finances.

Second, for offline power supply designs I utilize complete modules that take care of the critical task of rectification and isolation. I particularly like Mean Well products. They all come with the complete suite of certifications that apply world wide - UL, CE, TUV, etc. This offers another level of protection, documentation, and quality control.

Third, product insurance is one of the best ways to protect a small company from all sorts of liabilities and lawsuits. It is not required, but can prove extremely beneficial. A company can be sued by an individual, even when the individual intentionally missuses a product or causes harm by negligence. I am currently working to get a plan in place for my LLC.

Fourth, just plain good design.

Getting a product tested and listed by an NRTL is very expensive and time consuming. It is really only something that is pursued by medium to large companies. I work as an equipment engineer, and I regularly install equipment that is not NRTL certified (there are lots of large companies don't bother due to the cost, time, and other implications). However, my workplace/local authorities require NRTL certification on all equipment. I then work with a local agency to have everything NRTL Field Certified to the applicable standards.

So, if for some reason you wanted to install an SE/30 at your workplace and your workplace, state, or local jurisdiction required NRTL certification, you must have your SE/30 field inspected by a representative of a Nationally Recognized Testing Laboratory. Thus, the burden is not on me as a manufacturer to provide NRTL certification, but rather on the customer to meet the requirements of the installation location.

I'm definitely not an expert in this field, especially as a manufacturer, but there are many small companies that produce electronics and equipment that do not have their products NRTL listed/certified. It would be a literal company killer if that were the case. I would be super curious to get other folks experience, knowledge, and opinions on that matter, as it is an important subject.

-Chris
 
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