Wire is Not Orange, But Not Bright Yellow Either

Since I haven't closed the case while doing the the ATX power supply mod I have another question. Two yellow wires are a different tint than all the other yellow wire. They are slightly darker. They are by no means orange but they are noticeably not the bright yellow of the +12V wires. Why would this be? Did the manufacturer do this intentionally? Or did this bit of wire just happen to be off color? The two wires come from the same part of the PCB as the other yellow wires.

Maybe I am too curious?

It could be as simple as the manufacturer ran out of wires from one spool and switched to a new spool that had a slightly different tinted insulation. Or maybe the color signifies that those wires are powered by a separate 12v rail then the others. Power the supply on and use a meter to see what the wires read.

You don't have to use all the wires as just a couple of wires are enough to carry everything the average printer would need. If there are plenty of other 12v wires available, just use them and don't worry about the oddly colored ones.

Thank you, I will test the voltage.

Yes, there were plenty of wires. I tested how many wires can fit in the RAMPS connectors and found I can get four in per connector. So I have sixteen total for the yellow and black power (four bundles of four wires) and I figure the more the merrier.

I thought to leave three black and three yellow long to use for fans, etc. that I could control individually with switches. The off-shade one is one of the three extras.

I'm just learning about electricity/electronics so have all these very basic questions. But electricity is actually very cool .

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Garry Bartsch
Yes, there were plenty of wires. I tested how many wires can fit in the RAMPS connectors and found I can get four in per connector. So I have sixteen total for the yellow and black power (four bundles of four wires) and I figure the more the merrier.

The problem is sometimes screw terminals don't like to have multiple wires in there, especially close to what it physically can fit in the space. Having an excessive number is like drinking through multiple straws. One or two were probably more than what you could swallow. 3 or 4 straws might have allowed more drink to move at once, but if you can't swallow fast enough, it doesn't serve a benefit. Similarly, if two wires is enough to carry the conservative max 15 amps then 3 or 4 doesn't get you anything more for our use.

Personally I'd go with 3 wires each terminal as long as they are smaller than 19ga, or 2 if they are 18 or larger.

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cdru
The problem is sometimes screw terminals don't like to have multiple wires in there, especially close to what it physically can fit in the space.

On my Mendel90 I used three wires into the positive and three into the negative. I twisted and soldered them; then cut off the tip so the end was blunt and I haven't had a problem yet. But are you referring to the screw terminal not liking multiple loose strands? I seem to remember some people mentioning they had trouble with soldered wires coming loose in the screw terminal but I don't necessarily trust my memory because I may have misread something and can't find the source now.

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Garry Bartsch
But are you referring to the screw terminal not liking multiple loose strands? I seem to remember some people mentioning they had trouble with soldered wires coming loose in the screw terminal but I don't necessarily trust my memory because I may have misread something and can't find the source now.

Yes. Solid or strand, screw terminals like what the RAMPS have aren't great for terminating multiple wires.

Do these screw terminals like single solid wires? Seems like there are no other choices ... one solid or multiple strands. But if we take two or three wires, twist the strands, and flow solder into them we make a single strand, do we not? Seems like this is the best we can do?

In my experience a single smooth solid conductor isn't a problem, or even two if the wires are the same gauge. Once you flow solder multiple strands it's not smooth and consistent diameter. It's irregular shaped and if it's rotates slightly, the soldered wires may twist to a smaller diameter cross section, allowing it to loosen. As a work around, use a crimp ring to secure the wires together along with a short solid wire pigtail that can be secured.

Good idea with the pigtail. So - if I understand correctly - the issue with a solder filed section of multiple strand wire is its shape which could result in it becoming loose. And this looseness would cause poor connection. If the wire cross section happened to be an oval then if it were inserted with the flattest side on top and bottom it would be unable to ever twist due to the pressure exerted by the screw. In which case it should never become loose and cause a problem. I'm just thinking out loud to understand this issue.

Basically, I think you have the gist of it. I haven't by any means done research or anything like that aside from being a armchair mechanical engineer. There can be other issues at play: thermal expansion, vibration, etc that can cause things to loosen as well.

An alternative to the pigtail idea is to use a crimp wire pin. The crimp being designed to apply the constant mechancial force necessary to hold the different wires together, and the single pin to be held in place with the screw terminal.

Cool, that crimp wire pin would work well. Thanks.