5
\$\begingroup\$

The question title says it all: I need one wire in the cable to connect to 3 cups in a D-SUB connector.

How do I best do this?

Do I solder the cups together with a blob of solder?

Do I bridge the cups with additional wires?

Do I split the cable wire in 3 (awfully thin wire already)?

How is shrink wrap insulation applied?

\$\endgroup\$
2
  • 1
    \$\begingroup\$ You can use the wire as a jumper. Strip it long enough, and solder it to all the pins you need. If you can keep it mechanically stable and distances long enough from other conductors, no need for shrink wrap. Add some glue for mechanical stability after everything is soldered, if needed. \$\endgroup\$
    – Klas-Kenny
    Jan 11 at 8:20
  • 1
    \$\begingroup\$ "solder the cups together with a blob of solder?" You can do that, but then a generally good advice becomes really essential, esp with cheap connectors: Mount connector to a mating one while you are soldering it so you don't misalign the pins while the connector body is soft from heat. Not only is that likely to happen from the thermal mass of a solder blob, but a stiff solder bridge will really either perpetuate any misalignment, or evtl. fracture from the stress of a mating connector forcing it aligned. Risk of someone throttling you with that cable too, it can bust the mating connector.... \$\endgroup\$ Jan 11 at 18:11

2 Answers 2

19
\$\begingroup\$

Many quick & dirty alternatives are possible, but I'll try to answer how to do this professionally by the book (IPC).

Make 3 wires then join them with the single incoming wire at a separate solder joint.

  • Solder 3 wires to the dsub cups as usual. Peel & prepare them in advance by applying solder to them. Put some solder in the cup, then heat and insert.
  • Cut them at some sensible distance from the dsub. Ideally the wires to the dsub should have some mechanical strain relief somewhere, so you should take that in account when deciding how long the wires should be and where to join them. If it's some panel mount dsub then it might not matter.
  • If the 3 isolated wires are long enough (>100mm or so) then consider twisting them together.
  • Peel the single incoming wire and place a piece of shrink tube on it for later.
  • Peel the 3 wires, twist the naked wires together, then twist them with the peeled incoming wire. Solder.
  • Drag the shrink tube down from the single wire to cover the joint, then heat it.
\$\endgroup\$
3
  • \$\begingroup\$ Assuming the single wire is larger gauge than the 3 (thinking power supply here), I would suggest using a barrel crimp connector to join them (but solder the wires into it after crimping); much less messy than twisting the lot. \$\endgroup\$ Jan 12 at 2:59
  • \$\begingroup\$ @MichaelTracy Depends on the application I'd say. Soldering is superior against oxidation but often not ideal mechanically. On the local buses where I live, which are outdoors 24/7 in rain and snow, then put heat on to get really moist air. On those they have no doubt used barrel crimps for the "stop" buttons, because they never work and I'm quite certain it's because of oxidation. \$\endgroup\$
    – Lundin
    Jan 12 at 7:06
  • \$\begingroup\$ That's why I suggested crimping & soldering both, but in applications where moisture intrusion and corrosion is expected (or even vibration, for that matter), I would add the kind of heat shrink tubing with integral sealant. Of course, D-Subs are not the kind of connectors recommended for such use anyway. \$\endgroup\$ Jan 12 at 13:58
1
\$\begingroup\$

If the D cups are side by side, I'd use short pieces of bare wire cut into a U shape. Fit each end into a hole and solder like normal.

For 3 or more, use several pieces of bare wire, and the middle cups get two ends.

When fitting the incoming cable-wire, use one of the cups that has only a single bridging wire into it.

If your cups are all over the D connector then this doesn't work so well - for that situation use longer wires with insulation, and tie them off to prevent shorting.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.