Soldering Technique For DC Power Plugs - Is This A Good Idea

[lukestuts]

Hello fellow Dave-Fans,

We've got a big problem at work - we can't get the right AC/DC power supplies in time for a big project (400 units).

Instead, the boss has the warehouse guys chopping the ends of different power supplies and fitting correct-sized DC power plugs (as shown).

For the positive wire, instead of soldering to the smaller tab with the hole in it (labelled blue in the image), we are tinning the positive wire from the power supply and, while the solder is hot, putting it inside the central hole (labelled red).



The device is drawing around 0.5A at 5V. Is this going to work ok instead of using the smaller tab?

[Balaur]

Frankly, my own and possibly wildly inaccurate interpretation is that you either:

• will not adequately heat the inner piece of metal. Thus, the solder will not always adhere/wet correctly to the piece, or
• use too much heat and melt/damage the internal plastic sleeve

In any case, you can try both methods on a few of those connectors and perform a (destructive) test on them to see what's best.

While I consider that the quality of this kind of plugs varies wildly, my preferred method is to use some kind of isolation on the inner connector (heatshrink tubes are best, but it's not clear whether it's applicable in your case) or put a heatshrink tube on the connector or ultimately inject some glue inside the connector after assembly.

Cheers

[snoopen]

Well I'm a bit of a noob too but heck that soldering method sounds BAD. You need both surfaces hot to make a good solder joint. Throwing hot solder onto cold metal spells disaster.

I would just solder to the tab, forget the hole on the tab. You'd also need a small amount of slack on that wire when you crimp the whole wire in. It doesn't sound like much power to throw through it especially since you're already using the cable that came with the adaptor which should be rated for it's max output.

[lukestuts]

Thanks guys, that is very helpful!

[Psi]

Yeah, i very much doubt the solder will stick to the inside unless you tin the hole first.

It would probably be fine if you
- Heat up the hole
- Put a little solder down the hole until you see it flow
- Put the tinned wire into the hole.
- Fill the hole up with solder.

The plug isn't really designed to be soldered like that though, so you may have issues if the plastic starts to melt.

[Monkeh]

Definitely best just to solder to the tab. Don't worry about using the hole, it's nearly always too small anyway. Just tin the tab, tin your wire, and reflow it on.

[8086]

Would be much better to solder to the tab and cover with a bit of heatshrink, your method doesn't sound very reliable...