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DIY Speaker cable using RG/213

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19 hours ago, Monkeyboi said:

I have in some circumstances tinned only the very end of stripped multi-stranded conductors just to ensure the individual conductors remain consolidated and don't "fray", but leaving the majority of the bear wire as normal.  Having got caught out in my youth with the odd strand shorting out something with detrimental results this technique does not impact on the electrical conductivity of the connection if implemented as I have described above.

 

LOL read the fine print at the end of my previous post.

 

On the subject of soldering. Solder is not supposed to be used to secure the mechanical or electrical connection.  To ensure a soldered connection will be reliable long term, a sound mechanical and electrical connection has to be established BEFORE the joint is properly soldered.

 

Of course that all goes out the window with the mass manufacture of consumer electronics PCBs, but yes, that was the theory taught for lead to lead/tagstrip connections, which aren't as common these days.

 

The primary purpose of solder is to exclude moisture and air from the joint, thus preventing electrolysis and corrosion; both of which compromise the quality of the electrical connection which eventually lead to a fault.

 

The primary purposes of the solder is to ensure a good electrical connection, by providing a medium that will give maximum contact area between the soldered surfaces. And to make the joint mechanically sound by preventing movement between between the soldered surfaces. You could exclude moisture with silicone sealant or hot melt glue instead of solder, but it wouldn't make for a good electrical joint.

 

  Only the thinnest web of solder which has correctly flowed on the joint  and where the profile of the wire, lead or tag is clearly visible along with a shiny appearance are normally the hallmarks of a correctly soldered connection.

 

I agree with this bit. The amount of solder required for a good joint should show a concave fillet between the two surfaces, to allow a degree of flexibility without fracturing. A shiny appearance is usually what is aimed for, but some lead free solders will often show a slightly frosty appearance.

 

Soldering is an art and a science, unfortunately mostly misunderstood by those without knowledge or training in the subject.  

 

Cheers,

Alan R.

 

 

 

 

Inserted comments in your post.

And I also agree with the last statement.

Cheers

Bob M

Edited by bob_m_54
clarity

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1 hour ago, bob_m_54 said:

Inserted comments in your post.

And I also agree with the last statement.

Cheers

Bob M

Hi Bob,

 

Yes I read you last post and the ones before that.

 

Like yourself I have more than 4 decades experience in the industry.  Mostly on critical systems which don't normally employ the lead free soldering bath techniques found on a lot of commercial consumer equipment.  My training stems back to military spec high reliability mission critical systems; and to use the buzz phrase, "world's best practices".  

 

IMHO, teaching soldering amounts to nothing.  No offense suggested or implied.  I see the handiwork of TAFE lecturers who teach so called high reliability soldering courses and wouldn't trust their techniques or standard of reliability if only my backyards chooks depended on it.  🤣

 

Agreed,  clinching the joint does make it harder to remove the component especially from a PCB or a bifurcated tag.  But if your fault diagnosis is correct the component is stuffed anyway so you are doing to snip it off from the component side of the board for through hole mounting anyway.  That way the remaining lead can be removed without damage to the printed circuit track.

 

As for lead free solder.  Personally I don't use it in construction or repair work.  Usually lead free solder is the source of the problem and that's often the reason why the device in in for repair.  :(   I prefer the reliability and ease of use of a good quality 60% Sn / 38% Pb / 2% Cu alloy with a resin core for most work.  

 

I still maintain that for long term high reliability the joint must first be a sound electrical and mechanical connection before it is correctly soldered.  However that's just my opinion; and as the saying goes ".... opinions are like ******; everyone has at least one...." 😝

 

Cheers,

Alan R.

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Hi Alan, no offence taken. It sounds like you have very similar industry training and experience to mine. 29 years as a radio/avionics technician (22 RAAF, 7 as a civvy), with a lot of workshop experience, 7 years consumer electronics repairs, and about 5 years on both auto electrical and industrial electrical equipment installation, repair etc.

 

So, yes, I understand your point about mechanically sound joints prior to soldering, that was actually taught in the RAAF HRHS course, form day dot. And that is quite applicable in military, mission critical equipment, as you say. Interestingly, on aircraft, greater than 99% of wiring connections are crimped rather than soldered anyway, as it's proven to be a mechanically more sound method, with no detriment to electrical connection quality.

 

Consumer electronics, however, isn't usually constructed to the same rigorous quality. While clinched joints will sometimes be used, more often the component leads are merely poked through the hole, and solder as per this:

solder-side1.thumb.jpg.28037bfe6330ed82e26d8ad9d4ddd432.jpg

 

On some of the older Korean TVs, the leads would often have more than 6mm protruding through the board, which also made them prone to shorts, on high density boards.

 

And if you think TAFE teachers are poor solderers, you should see some of the work done by Auto Elecs LOL.

I fear we are also getting way off topic, so I'll leave it at that.

 

Cheers

Bob

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On 23/09/2018 at 11:42 AM, Monkeyboi said:

I still maintain that for long term high reliability the joint must first be a sound electrical and mechanical connection before it is correctly soldered. 

This.

 

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