Aaargh!
Quote:
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The only problem with doing a good job of soldering leads to valve base tags, IE making a good mechanical joint by wrapping a few turns and cinching with pliers, is that it's a ****** to unsolder
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Andy, me ole mate, you've just succinctly described why you don't wrap a few turns and cinch up with pliers! You're building a piece of electronic equipment, not mooring the Lusitania
There are two good reasons not to wrap your wire end "a few turns" around a solder tag*:
1. It ain't necessary for making a good mechanical and electrical joint**
2. You might be the poor prat who has to take it back off again at some time in the future!
All you need to do is to form the joint shown plan view in the attachment:
Strip off 1/2" of insulation
Form the joint shown with fine needle nose pliers and your thumbnail (if you're using multi-strand hookup wire rather than single core, tin it first to make a solid single conductor before forming the joint). The "neck" of the joint from the end of the insulation to the first bend should be less than 1/16". Two quick movements - takes longer to describe than it does to do it.
Snip off the free end of the joint to size. It wants to be wide enough to accommodate the solder tag, but not so wide that it overhangs the joint significantly.
Tin the solder tag (never mind if it's pre-tinned, do it again!) and your joint (if you haven't done so already). Slide the joint over the tag. You can nip it up gently in the direction of the arrows if needed to hold it in place while you do the joint.
Dab the joint with flux. (Oh yes, you do!***) Load a clean iron with just enough solder to do the joint. Touch the iron briefly to the job. The solder should wick into the joint quickly and smoothly. Remove the iron quickly before the insulation starts to discolour and char.
When the job is done, there shouldn't be a blob of solder over the joint. You should be able to see the outline of both the tag and the hookup wire clearly, with just a tiny fillet of solder between the two.
This is the method we were taught in my apprenticeship in the '60s and was the approved method for aircraft electronic equipment. The NASA standard today isn't significantly different.
Cheers,
Frank
* Yes, I know a lot of manufacturers did it back in the day, but this was for commercial production reasons. One guy on the line could make a ferret's nest of components by wrapping them in as you describe, then the next guy would flash round the job with a soldering iron. Didn't matter - some other poor sap would have to deal with it later if there was a problem. I expect that this is why most of us at some stage have worked on an old radio or somesuch and found an unsoldered joint, that had obviously
never been soldered at the factory.
** "Good mechanical" in this instance means just strong enough for the task - the joint shouldn't be under any mechanical strain. If it is, then you have a design problem with your wiring loom, your strain relief, your component positioning, or all three!
*** Yes, solders like Ersin have flux incorporated, but I find that you need to keep your iron in place for slightly longer for the flux to activate and get a good flow, whereas with clean components, a dedicated flux and a hot iron (with the right-sized tip!), the flow happens almost instantaneously without risking burning your insulation.