How to stick it all together?

[Richardcavell]

Hi, everyone. Today I tediously soldered a 16-way ribbon cable to veroboard at one end and a DB-25 socket at the other end. Because I was manually stripping the wires and so on, it's possible that if either end is jiggled about, some wires might accidentally be crossed. It's also possible that if I give it a good yank, one or more connections might get ripped out. I want to stick it all down with an insulator.

At the shops I can buy a glue gun and glue sticks. Is that what I need? Or is there some other stuff that I can use?

Richard

 

[dougy83]

You could have used an IDC header which gives a good connection and secures the cable, e.g. **broken link removed** There's also ones having 0.3" spacing if the 0.1" is too narrow.

You can use a hot glue gun, but I've found the glue is hard and likely to remove itself from flat surfaces. Silicone sealant seems better, or you could use some other flexible glue.

EDIT: You can also get crimp IDC 25Pin D connectors, which means you don't have to solder the ribbon cable - just put the ribbon in and clamp in a vice.

 

[Richardcavell]

I ought to explain that I went with the DB-25 connector because it meets my aspirational needs as an eccentric. I realize there are more practical solutions. Asking me why I use a DB-25 for this purpose is like asking Andy Warhol why he painted a soup can.

 

[dougy83]

I think his soup can has received more attention than your use of a D25 ever will sorry. D connectors are used for all kinds of things; soup cans are only used for soup.

I wasn't questioning why you're using a D25, just saying that the use of a crimp IDC (insulation-displacement connector) type would have been more suitable and non-labour-intensive than using a solder bucket termination type. Same goes for the connection to the PCB. There are parts made for this and they're cheap.

 

[Richardcavell]

Can you find a part that will connect a DB25 to a Veroboard with 2.54mm pitch? All the ones I can find have staggered rows and the wrong pitch.

Of course one day I will learn to etch my own PCBs. But for now I'm stuck with Veroboard.

 

[dougy83]

I haven't seen a D25 PCB mount connector with 0.1" pitch. As mentioned above, the IDC termination headers are 0.1", which will fit into the perfboard/veroboard perfectly.

 

[JimB]

Today I tediously soldered a 16-way ribbon cable to veroboard at one end and a DB-25 socket at the other end. Because I was manually stripping the wires and so on, it's possible that if either end is jiggled about, some wires might accidentally be crossed. It's also possible that if I give it a good yank, one or more connections might get ripped out.

May I suggest that a good place to start would be to improve your soldering and wire stripping technique, rather than just covering it in sticky stuff.

When you have separated the strands of the ribbon cable, consider where each strand will connect on the DB25.
Maybe that some strands need to be longer than others to get a good "lay" to the strands rather than just a jumble.
Sometimes the best that you can do is still a jumble, but at least aim for something which is tidy.

When stripping the insulation from the wires, consider how much wire will go into the solder bucket on the connector pin.
You only need to strip about 3mm of insulation.
When the insulation is stripped, gently twist the strands of wire so that they lay together and then tin the exposed strands.
Dont use too much solder and make sure that the soldering iron is not so hot that it melts and burns the insulation.


About the connector.
Make sure that the connector is held firmly so that it is not skating around the workbench as you try to solder.
Use a small vise to hold the connector.
Not got a vise?
Try using a blob of BluTack, in the past I have used an adjustable spanner as an impromptu vise.
On the connector, fill each solder bucket with solder.
Not so much that the solder forms a bulging blob, just enough that there is a concave meniscus to the solder surface inside the solder bucket.

Now we are ready to solder the wires into the solder buckets.
Ensure that the iron is clean and has a small amount of solder on the tip,
touch the iron on the side of the solder bucket to melt the solder inside and insert the wire up to the insulation.
Remove the soldering iron from the pin and hold the wire steady whilst the solder solidifies.

Repeat for each wire and voila! you have a nice tidy connector which does not need to be daubed with anything.

JimB

 

[audioguru]

I strip and connect ribbon cable neatly to veroboard. Yours has broken strands of wires sticking out and uninsulated pieces of wires.

I use a wire-stripper tool, not a knife nor my teeth.

 

[JimB]

AG said:

I use a wire-stripper tool, not a knife nor my teeth.

I fully agree with that.

Also on the veroboard, consider the lay of the cable.
Sixteen strips of vero is wider than the ribbon cable, to get it to lay neatly the outer cores of the cable will need to be longer than the inner cores (if the cable is to come away from the board at a right angle).
You have core numbers 3 and 16 significantly shorter than the rest.
This results in two problems:
1 these two cores take all the strain when the cable is pulled
2 the longer cores bend and bunch up.

Consider the possibility that it may be neater to solder the wire cores flat on the track side of the board.

JimB

 

[OlPhart]

old trick

Howdy, from the mid-late '70s: solder cup row spacing force fits over .062" board. Many boards had a layout using a staggered pattern for just this. For generic perfboard, scrape off any edge connector leaves, push the D25 on & use resistor lead cutoffs to tag it all back in.

 

[ChrisP58]

Well, I'm all for using the parts one has on hand whenever possible. That being said, we always need to understand the applicability of what we have to what we need, and judge the pros and cons accordingly.

Ribbon cable is optimized for use with insulation displacement connectors. As such, the insulation is softer, and, since it is not intended to be soldered, the insulation has a lower temperature rating. So it is much more difficult to work with for point-to-point soldered connections than good hook-up wire is. My preferred wire type is irradiated PVC. UL 1429

 

[Richardcavell]

Thanks for all the suggestions about my surgical technique.

As to the stick-it-down question, today I bought some epoxy resin. In Australia it goes under the trade name Araldite. Works superbly. It's clear, sticks everything down, really strong. Makes my fiddly DB25 connector magically robust. It comes in two tubes and you mix them together, or you can get elegant nozzles that do the mixing inside the nozzle.

 

[JimB]

I bought some epoxy resin. In Australia it goes under the trade name Araldite.

Same in the UK.

JimB

 

[Richardcavell]

And by the way I bought some of those IDC connector crimping thingies. They work fantastically! I'm impressed at how neatly they separate the signals from each of the ribbon-cable wires. I'm using a vice to squash it together, and I recommend that to others.