Have you ever seen this happening with cable jackets?

[jkim]

I wonder if any of you can explain this.

I have had some long XLR mic cables laying around. The cables were made by a name brand---Kopul 3000 series with Neutrik connectors selling at B&H Photo.

Since I have not been using them for a long time, I decided to salvage the cables and connectors to make some short adapter cables.

After my soldering job, I found some pins that were not supposed to be connected had some level of resistance, like 10 to 20 kOhm. So, I tried to look for any bad soldering job. Couldn't find any. Puzzled, desoldered everything, checked on any defect of the connectors, and resoldered. Found the same problem.

After checking everything, I finally found that the PVC jackets of the microphone cable's inner cores became conductive after soldering! I did not apply unreasonably excessive heat extensively when soldering. Yet this happened to the inner core jackets. Is this possible? Have you ever experienced anything like this?

 

[DonH56]

I wonder if any of you can explain this.

I have had some long XLR mic cables laying around. The cables were made by a name brand---Kopul 3000 series with Neutrik connectors selling at B&H Photo.

Since I have not been using them for a long time, I decided to salvage the cables and connectors to make some short adapter cables.

After my soldering job, I found some pins that were not supposed to be connected had some level of resistance, like 10 to 20 kOhm. So, I tried to look for any bad soldering job. Couldn't find any. Puzzled, desoldered everything, checked on any defect of the connectors, and resoldered. Found the same problem.

After checking everything, I finally found that the PVC jackets of the microphone cable's inner cores became conductive after soldering! I did not apply unreasonably excessive heat extensively when soldering. Yet this happened to the inner core jackets. Is this possible? Have you ever experienced anything like this?

Not the jackets themselves IME, but soldering can embed solder particles in the jackets that lead to conductivity (all the way to short circuits). Tinning can also cause sintering, tiny shafts of metal poking through the insulation. You could try cutting off a couple of inches and carefully soldering, or just crimping, the connectors back on.

Also double check your DMM was not set to M-ohms...

 

[jkim]

Not the jackets themselves IME, but soldering can embed solder particles in the jackets that lead to conductivity (all the way to short circuits). Tinning can also cause sintering, tiny shafts of metal poking through the insulation. You could try cutting off a couple of inches and carefully soldering, or just crimping, the connectors back on.

Also double check your DMM was not set to M-ohms...

Thanks for the insights. I believe this particular jacket is defective in so easily absorbing solder particles. I recently did quite a few cable making jobs using exactly the same setup. Only this cable exhibited the same problem multiple times. All other microphone cables were fine.

 

[DonH56]

Thanks for the insights. I believe this particular jacket is defective in so easily absorbing solder particles. I recently did quite a few cable making jobs using exactly the same setup. Only this cable exhibited the same problem multiple times. All other microphone cables were fine.

Possibly also the internal insulation is melting and absorbing rosin and solder particles. Either way, toss it and good riddance! Glad you measured and noticed the problem before putting it back in service; when that happened to me, I found out after plugging it back in. Don't do that.