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I bought a set of banana plugs of the style shown here (with rough 3d model to clarify the shape of the terminal because shiny metal is hard to photograph!).

The site I got them from (here) didn't go into detail and there is no datasheet, plus I cannot find any links on the googles that match this exact shape of terminal. It seems that there are many dozens of different types of 4mm banana plugs and this is a fairly rare breed.

enter image description here

My plan is to solder in some 14 AWG wire by first tinning the wire generously, inserting it into the hole at the end face of the terminal and then feeding more solder in through the hole in the side until the connection is full of solder.

Is that the correct way to install a wire into this kind of terminal? I think it is but I have also seen terminals that are intended for solderless connection to the cable (eg. by lacing the strands through the various holes and thus creating gas-tight connections through interference fit and friction).

I'm going to be using these for 3.3 V, 5 V and 12 V power up to max 4 Amps each (it's an ATX desktop power supply project). Edit: The PSU has overcurrent protection which kicks in at 150% rated current, and I'm going to put some 5A fuses in there too for good measure.

If this isn't the best way, could you please suggest a better method?

Also, if anyone could scare up a datasheet for this part that would be great, I'm drawing blanks at the moment.

EDIT: Further to @Neil_UK's answer, I would suggest that 14 AWG is about the biggest cable size that this type of connector can comfortably accommodate. My Weller WHS40 iron was struggling but it did manage to get the job done. Tinning the wire very thoroughly first (without increasing the diameter of the conductor) and then inserting into the terminal, then flooding the aperture with enough solder to completely fill the void resulted in a very strong joint.

If you have a 200 Watt soldering gun and a bunch of flux, then you're good to go. :)

Edit: Here's the "datasheet" if it can be called that...

enter image description here

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  • \$\begingroup\$ They're rather unusual. Are you sure they're not solderless? i.e., Is there clearance between the top of the pin and the screw-on sleeve? If you run the wire in at the top and out at the side with enough to wrap nearly once around can you screw the sleeve on? \$\endgroup\$
    – Transistor
    Aug 2, 2017 at 17:01
  • \$\begingroup\$ @Transistor, I'm not sure, no. This is what I had in the back of my mind. With a smaller AWG wire (26 lets say) I think I could do a simple wire wrap as you describe. But for larger gauges such as the 14 AWG I'm using, I think it would be too tight, it might even split the plastic. With substantial current (4 A is higher than most of the stuff I've worked with before) I'd be concerned about relying on wrapping the wire being unable to give a good low-resistance connection. \$\endgroup\$
    – user98663
    Aug 2, 2017 at 17:05

1 Answer 1

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This type of terminal is intended to be soldered in the way you describe.

Check carefully the interface between the spring cage, and the pin. I bought some cheap 4mm plugs which failed to make a secure contact between the inside of the cage and the outside of the pin. The I/D of the cage was too large, and rotated easily on the pin, even when the spring cage was compressed in the right size hole. Even if it rotates easily initially, it should tighten to the pin when inserted into a socket. I would be nervous about passing 8A through the connector if the pin to cage connection was poor.

I ended up soldering (very quickly and carefully, to avoid solder wicking into the cage (after trashing one that way)) the cage to the pin on the leading end, for my peace of mind.

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  • \$\begingroup\$ The spring cages are very tight on these ones, even more so when inserted into a binding post. I mistakenly put 8 Amps on my question but that's unlikely unless a dead short occurs, but there are fuses and overcurrent detection in my PSU so I think it's not a problem. \$\endgroup\$
    – user98663
    Aug 2, 2017 at 17:02
  • \$\begingroup\$ @Wossname If the cages are tight, then that's good, I got bit by buying too cheap. \$\endgroup\$
    – Neil_UK
    Aug 2, 2017 at 17:05
  • \$\begingroup\$ With this type of plug there is no risk of solder ending up near the cage because the main body of metal is solid and not hollow, the wire only inserts about 5 or 6mm before it hits the bottom of the blind hole. They are very substantial and tough, surprisingly so given the low price (£1 each). \$\endgroup\$
    – user98663
    Aug 3, 2017 at 6:53

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