Why have I no continuity signal here?

[shawn gibson]

Hi all, first post, and pre-emptive thank you for your help.

In anticipation of redoing all of the wiring with the computer I'm putting together, I decided to add a PET sleeve to a pair of my headphones this morning. Having just spent about $500 Cdn in connectors, wires, decent crimpers, all the pins, etc. for this computer, along with way too much RGB and ARGB bling, I figured I'd better do some testing/experimenting to gain a little experience before blowing my build up out of arrogant stupidity lol. My electrical experience is limited to changing turn signals and other such tasks with my motorcycles...

Upon stripping the outer wire casing of my headphone cable, I was surprised to see that none of the wires inside were shielded. I'll attach an image here to show what I mean.

After loosely re-connecting the long end of the cable to the short part I cut where the jack is, I could not get a signal when plugged back in to my audio source. I then tried to get a continuity beep on the multi-tester I bought, and nothing gets continuity - including touching the probes to the same wire-strand just an inch apart. I tested the unit with a regular 18AWG wire, and it indeed works fine, even down to a single strand of wire 6" apart. So it's not the multi-tester or the setting I used.

So now I'm concerned that I may not have the knowledge to to re-do all of the wiring with my computer. To be fair, the wiring from my headphones is strange to me, as noted because none of the internal wires are shielded. And near as I can tell, most of the RGB and PWM fan wiring I'll be modifying looks like 'the normal type' of wire, whatever that means.

So, if I may, a couple of questions.

1) Why can't I get any sort of signal from the attached image? I'm guessing I may need to find another cable for my headphones lol?

2) what sorts of preliminary advice might you have to help me with the computer wire re-wire? I can expand on what I'm doing if anyone wishes to help me out here

I'm hoping to be able to participate in the forum over the next few weeks as my computer build moves along...

Merci
Shawn

 

[stewartrossinv]

The headphone cable you show is (in my opinion) very difficult to make suitable connections using DIY soldering techniques. The cable comprises bunches of very fine-stranded wires, each strand covered with an insulating lacquer. Because the strands are all insulated by the lacquer there is no need for separate PVC insulation. It is also why you can't get a continuity reading, as you will only be able to connect these strands if you can remove the lacquer from the area you want to solder first. The lacquer can be removed either by heating or by abrasion, but given the number of strands involved this can be a bit hit-and-miss.

Unlike general audio signal cables, headphone cables do not need to have screening (shielding), as the signal levels involved are large enough, and the impedance of the transducers involved low enough, to make them relatively immune to induced noise.

The cable for your computer project is quite different, and generally easier to connect, perhaps with the exception of ribbon cables. However, most items you wish to connect together should already have pre-terminated cables attached (as for example with the power supply unit) or you can purchase suitable cables from suppliers (for example for SATA SSD or disk connections).

 

[shawn gibson]

Thank you, stewartrossinv, very helpful. I had no idea about the lacquer, but it makes perfect sense.

I'll have to cobble something together from some of the other 1/8" stereo cables I have here, which are many, mostly for speakers, not headphones. Hopefully they are not all like this one, all lacquered up like my Scottish relatives

Would I be degrading the volume or sound quality to use much thicker wires when I make the new 1/8th-1/8th" cable for my headphones? They're powered by a small external audio interface via USB. I added an inline link there to show you what I mean (I'll add other inline links here as appropriate, as well).

With my computer build, the cables I'll be working with are 3-pin 5v ARGB lighting, 4-pin 12v RGB lighting, 4-pin PWM fan cables and SATA power (not data), plus some new PSU connectors.

The modifications I'll be making are, I hope, simple(?) I'll be adding appropriately sized PET braided sleeving (I bought 2, 4, 6, 8, 10, 13 and 16mm diameters just to cover my bases; I can use any leftover material to clean up my desktop cabling). From my initial experimenting, it is impossible to push the appropriately-sized sleeving into something as thick as a fan connector, so I'll have to cut the connectors off and then reassemble once sleeved. Hence the ruined headphone cable lol!

That's one mod, and the other will be shortening/lengthening wires in order to daisy chain them or otherwise get them to fit very nicely in my case, which I'd like top show off a bit.

I've purchased a bunch of RGB lighting cable modifiers (straight, 90deg, M-M, Female-Female, M-F etc.), a bunch of fan connectors, Male and Female, and their gold-plated pins (which I've heard, crimping the pins, will take a lot of practice), and a bunch of female SATA power connectors.

As well, if I don't get timid, I'd like to re-cap the motherboard's ATX power connectors (the 2x2, 8x2, and 12x2 connectors and some pins) which are connected directly to the PSU on the other end.

A question I do have with all of this is, other than checking for continuity and shorting once I've created these cables, what else would it be wise for me to check with the multimeter?

As I say, I know a lot of this could be plug-and-play, but I'd like to make this a project for myself. I do like to be unique and learn new things at the same time

Thank you once more for any help
Shawn

 

[stewartrossinv]

Hi Shawn. I guess you want to show off the innards of your computer as best as possible, hence the PET braided sleeving. I would advise that you do the minimum of cutting and reconnecting, as home-modification will potentially degrade the reliability of (normally excellent) commercially-produced cables. For instance, over many years I cannot recall any instances of failure of ATX power connectors (unlike the PSUs themselves). The standard installation cabling on most computer components has not been a major failure source in my experience (which includes being responsible for PC installations of many hundreds in a college environment for five years in the early 2000s, and in a fire service in Scotland from 2011 to 2013.)

The use of a multimeter is quite limited for test purposes. From a continuity perspective make sure that when you test the resistance of the cable you get a reading of about zero ohms (the cables are so short that their resistance will be negligible, hence showing as zero ohms on your multimeter). Anything showing above zero ohms means the connection is poor and hence liable to fail; in ATX power connectors this could cause overheating and pose a potential fire risk.

Re your headphones rewire, you are unlikely to hear any difference at all in sound quality by changing the cables. Be careful using thicker cable, simply because when it comes to connecting to the small headphone speakers/transducers the coil connections can be very delicate, and soldering a thicker cable on can overheat and potentially damage the connection to the transducer.

-Stewart

 

[shawn gibson]

Thank yo, Stewart. I'm glad to be aware of your experience here, with PSUs especially. My only goal there was to change the connectors from boring black to a bright red, like the rest of my cables. I was going to do this on an after-market extension (this thing, actually, in my shopping cart). Remove the motherboard connector, replace with the red one and newly-purchased gold plated pins. However, I would't know if I had created a good, secure, and SAFE connection. I don't have that kind of experience. For this mod, it might be best to rely on the pros, and just get an entirely new harness from someone like these guys, and request red connectors. However, they too, are not OEM, so what would your own experience say there (this particular company notwithstanding, of course)?

I will heed your advice with the resistance as well, thank you. I do seem to remember that one should use minimal solder and only enough heat as necessary? I purchased .6mm lead/tin 63/37 flux rosin core. I have a number of variously sized (and Watt-ed, I believe) soldering irons, mostly for pyrography with the leather bags I make; not much used for electronics, though, just augmenting thick motorcycle wires for turn signals and headlamps, etc. (wire-to-wire solder joints).

If you suggest against any OEM PSU mods, including aftermarket replacement, I will heed that advice.

Shawn

 

[stewartrossinv]

Hi Shaun. The cables you linked look well made, though expensive! I have no issues at all with those cables vs those supplied by the OEM. If you remove the connectors on any of these cables yourself and fit your own you take responsibility for any subsequent failure (i.e. you invalidate the warranty you would receive from these suppliers).

With the PSU connectors, I'd be cautious about cutting off the machine-fitted plugs and crimping your own solutions. Crimp connections can be very, very strong - but getting them right means using the right tool for the job, and what that would be for your pre-purchased gold-plated pins I'm not sure. A ratchet-based ferrule crimp tool seems most likely to me, but you'd need to check the technical spec of your pins to know for sure. Don't use a manual lever-type crimp tool relying on your judgment of leverage alone - it's unlikely you will get consistent results, and with so many pins involved you increase the chance of a failure that could ultimately damage the PSU, the motherboard and other components you connect the PSU to.

-Stewart

 

[Lucien Nunes]

Shawn, some excellent advice there from Stewart. Two things I would add; some kinds of enamelled wire as used in headphone cables use a low temperature meltable enamel, that can be soldered as-is without stripping. It does still require significant heat, so you must tin the ends thoroughly to penetrate the enamel before attempting to solder them to the connector. Do this in a well-ventilated area because the process can give off poisonous isocyanate fumes.

Secondly, have you actually tried fitting the sleeving over the various connectors? Some types expand quite dramatically when compressed and can be fed over relatively bulky connectors. Another method for many PC power cables is to get the appropriate tool for disengaging the crimp contact inserts from the plastic housing, make a careful note of the pinout (tagging individual wires where needed) and remove them. Once you have fed them through the sleeving, reset the retaining barbs on the contacts back into their proper positions and click them back into the housing.

 

[shawn gibson]

Thank you both, again excellent advice and knowledge I do not have.

Lucien, I've spent a couple of days concocting various fishing jigs to get the larger parts through (female fan connectors are about as big as I can get through, wrapping in plastic and WD40ing before pulling my snake...can't believe I just said that lol). I just don't have the (talent? technique? hands?) to get anything large through, like a USB connector, for example, or a male 4-pin fan connector, without going up a couple of sizes with the PET sleeve, which ends up looking blobby, frumpy and amateurish. Heat gun does not reduce the size afterwards, either

Thanks for the heat tip as well, but I've already been able to pull together some new wires/stereo plugs to get a cable half made. Pre-solder, it works

Regarding the crimping tool, I did my best to purchase something that was rated well on Amazon, and not cheap, but it is probably not one of the professional ones you advise of. It's THIS and in my hand it looks well machined, FWIW.

I did my best, with zero prior knowledge, to ensure it would work with the connection pins I needed (these, these, these and a bunch of straight/angled, 3- and 4-pin, M/F variations of these are what I purchased, replacing the ones that come with the connectors linked above, with plenty of spares of everything to get some miles under my belt before ripping away at the actual project). This stuff is still in shipping, so I can't comment on any of the pins or connectors.

As for consistency, as an artist, woodworker and leather-bag maker, I do have a number of precise measurement tools (including a few sets of Vernier calipers which can measure down to the micron, I believe), as well as a stereo microscope and a compound microscope as well (lots of hobbies lol) so if I know what to look for, I might be able to ensure some pretty decent consistency throughout? That's my thought, but please tell me if you think it's still a crap-shoot, so to speak...

I've sunk several grand into this computer, so I do not want to be doing things which might be prone to fail even to the best of my eye, measurement devices and meter thinking I've done a good job.

Shawn
ps, I truly regret not studying electronics when I was young.

 

[stewartrossinv]

All the best with your project Shawn. You've put a lot of time, effort and money into it - and your enthusiasm is clear to see too!

-Stewart

 

[shawn gibson]

Thank you Sir! I will come back with some pics when I'm done. Though I suspect I'll be back asking more questions long before that time comes...

Thank you again for the help,
Shawn