Never soldered from new

[vinrads]

I am repairing a small Dulci radio and noticed a joint never soldered I don't see this to often , Mick.

Sorry for the poor quality It looked OK on the camera the bad joint is to the left of the resistor.

[Hartley118]

It can happen in the best of circles.

A year or two ago, I was suffering occasional intermittency with my otherwise trusty 35-year-old Bruel & Kjaer 2215 precision sound level meter.

I finally traced the problem to a totally unsoldered joint on one of the rotary switches. The mechanical joint carefully secured prior to the intended soldering had gone straight through its factory test process and gone on to survive another 30 years!

Martin

[julie_m]

Back in the Day, great importance was attached to the idea of making a mechanically-sound connection that can support itself before applying any solder.

All this changed with the advent of the printed circuit board and wave-soldering machinery .....

[Peter.N.]

It used to happen occasionally with TV's and its amazing how long they would work like that, it was only really when the tinned surface oxidised that the problem appeared and that could have been years in a dry atmosphere.

Peter

[Hartley118]

Of course, the 'official' version was called wirewrap, and was remarkably reliable.

Very good for prototyping and small quantity production.

Is it still around?

Martin

[vinrads]

I wasn't looking for a fault except that the sound would fade for a few seconds and then come back OK , it just so happens that the the pin in question is one of the heater pins , we will see! Mick.

[Nuvistor]

A wirewrap done correctly is much more stable than a soldered connection especially the "modified wrap". The ones used by Thorn on their TV's used larger diameter wire than used in many other low voltage, low current application.
Many a happy hour spent reconfiguring back planes on mini computers with a wire wrap tool, still have the wirewrap tool somewhere.
https://en.m.wikipedia.org/wiki/Wire_wrap
Frank

[TonyDuell]

Originally Posted by Nuvistor

Many a happy hour spent reconfiguring back planes on mini computers with a wire wrap tool, still have the wirewrap tool somewhere.

Still have the minicomputer -- in the next room. And of course the wirewrap tool and wire to modify backplane connections.

And my experience is that properly done wirewrapping is very reliable. I've got machines with many thousands of such connections, over 40 years old, with no problems.

But puting a wire through a solder tag hole and squeezing it with pliers is not the same (the pressure is much less, you don't get a cold weld formed) and is not going to be that reliable. As others have said, it will work most of the time and fail when you need it most (or when you have no tools or test gear around).

[Nuvistor]

Originally Posted by TonyDuell

But puting a wire through a solder tag hole and squeezing it with pliers is not the same (the pressure is much less, you don't get a cold weld formed) and is not going to be that reliable. As others have said, it will work most of the time and fail when you need it most (or when you have no tools or test gear around).

Very true.

[Phil G4SPZ]

I don't think I've ever seen this, either. Plenty of dry joints, but not a never-soldered joint.

At least you can truthfully tell people that the fault was caused by "just a loose wire", a fault encountered as rarely as a faulty picture valve or an overwound clock!

[G4YVM David]

I remember once hearing an engineer claim that a good wire wrap effected a cold-weld amd was thoroughly satisfactory. Whether true or not i cannot say.

D

[Oldcodger]

Don't forget that over the years a soldered joint may crystallise and dry out. I had an old PC monitor where a knock brought picture back to normal. Turned out that diodes on the neck of the CRT had gone this way .
Fault we saw often in the TX stages of high powered radios as supplied to HM forces ,even when higher melting point solder was used.
As for the wire wrap forming a "cold weld"- I wish I had cash for the number of these I traced on the TRS various DF . Best way of tracing them was to use a low level tone, as a normal level one would wet the joint.

[P.Pilcher]

My first journey into the delights of television tape recording commenced with the purchase of a second hand N1500 (they were then £700 new). I soon discovered that its frame hold did not seem to work and on investigation I found that much servicing work had gone on in the region of the eddy current tape speed control circuitry - obviously to no avail. Further close examination eventually revealed two transistors whose leads had never been soldered in from new and a few blobs of solder provided me with a reliable machine for several years until I decided to swop it for a N1700 with the extra recording time.

P.P.

[McMurdo]

I still see stuff at work that's been fine for 20-30 years with a non-soldered joint that has only just failed, as others have said it's when the leg tarnishes. Sometimes the client is incredulous that it was the actual fault.
Regarding wire-wrap, it was used exclusively on the Apollo guidance computer where reliability in the face of vibration and people's lives were the prime concern.

[Station X]

Originally Posted by julie_m

Back in the Day, great importance was attached to the idea of making a mechanically-sound connection that can support itself before applying any solder.

All this changed with the advent of the printed circuit board and wave-soldering machinery .....

This is the one I remember:-

https://www.vintage-radio.net/forum/...08&postcount=8

[G6Tanuki]

Originally Posted by G4YVM David

I remember once hearing an engineer claim that a good wire wrap effected a cold-weld amd was thoroughly satisfactory. Whether true or not i cannot say.

True indeed: the entire UK telephone-exchange infrastructure was based on wire-wrap from the mid-1960s through to the retirement of the last TXE4A sometime in the first years of this century.

Wire-wrap was also used extensively on 1960s/1970s/1980s computer backplanes [the PDP7/8/9/10/11/20 series being prime examples] and worked perfectly!

[Wendymott]

Hi peeps... thought you may like to see this.... its my Wrap/ Unwrap tool from my days in the NEI Tv factory in Bradford... all the engineers and some production staff had them.... mine maybe the only one left.

[Nickthedentist]

No pics I'm afraid but my parents Hacker VHF Herald from c.1970 always jumped off-tune sporadically, causing silence because of the interstation muting feature, which then meant that the set got left on and ran down its expensive PP9s. The repairers found nothing wrong. It soon got chucked in the loft and replaced with a Taiwanese Ferguson which never misbehaved.

15 years later, I was allowed to play with it and found that pressure on the VHF tuner head caused signals to come and go. I popped off the cover and found a cluster of wires which had been twisted together but never soldered. A second with the soldering iron and it was perfect, and has remained so for the last 30+ years.

[G4YVM David]

Oldcodger, "Best way of tracing them was to use a low level tone, as a normal level one would wet the joint"...what does this mean? You've got me thinking about 'dry' joints...a term I use like everyone else and a thing i can see etc when soldering. But how can a Tone wet a Joint??

The more I read the less I know!

D

[Hartley118]

Two metal surfaces touching but not actually conducting a small signal are commonly insulated from each other by a thin layer of oxide. Something similar can happen in a dry joint.

A substantial voltage will break through the oxide layer and will temporarily or even permanently remake or 'wet' the connection.

This is why connectors for critical applications have gold plating, which doesn't oxidise.

On the other hand mains connections or even telephone lines (48V) are permanently 'wet' are are much less critical when it comes to connector surfaces.

Martin