Electronics > Beginners
Unsoldering 'reef knots' ...?
jaunty:
I guess i'll post this in the beginner section because it should be basic advice i've never really learned ... 'm working on a vintage (1970 ish) yamaha synthesizer and while the original craftsmanship is excellent - it also means all the components (incl. stranded wire is looped through and around lugs at least twice - it appears to have been even pre-tensioned (so tight!) before soldering ... it's all quasi aerospace stuff ... which also means it's a NIGHTMARE to unsolder - in this case i have VERY VERY short leads coming from the OEM xformer (about 3 cm long) that i don't DARE shorten ... so my common sense tells me I should maybe just try suck the solder off first then attempt to cut the lead to the longest reasonable length i can work with (at least 3 mm) and the reheat and try to wrestle the wire off the lug - i've been mostly doing this but it's still extremely time consuming ... also resulting in melted insulators etc (UGH)
so what i'm asking is .... is there a better way????
tkamiya:
A decent de-soldering iron will remove enough solder that you can then use an iron and a needle nose to unwind the wrapping. Sometimes, I am lucky enough to PEEL the wire off without re-heating.
Otherwise, I'd remove as mush solder as I can, then cut some place leaving as much lead as possible. I think, the priority is, to save the transformer. 3cm is enough to solder a new wire and shrink tube. If you get too involved and damage the transformer, it's basically game over. You can deal with 3cm. (that's a tad more than an inch)
Brumby:
I, too, support the "remove as much solder as possible and try peeling the lead away from the tag" approach. However, if this isn't practical and you are really desperate to save component lead length, then you might consider cutting a "split" in the tag so you can slide the looped lead off (whilst solder is molten). Straighten the lead (if you need) when it's out.
I am always conscious of the potential for failure from metal fatigue when reworking stuff like this. Can be frustrating if somethings fails after all your care.
jaunty:
thanks kiddos ... yes i ended up splitting one of the lugs - partly out of frustration (though against my 'do no damage' policy ... for the critical short ones i did as well as i could just trying to coax the wire off with the soldering iron under the stereo zoom microscope (don't know HOW anyone works without one!! - even for larger stuff) though i'm not sure that's the best route. I had about 20 more to disconnect (this was JUST so i could get the power supply board out of a frame where i could work on it!!!) - so i ended up just cutting them all mid-wire and so i'll just resplice them later with heat shrink ... thanks again for your thoughts ... though if anyone knows a 'magic' method - please feel free to contribute!!
Raj:
I would have brought in a helper to operate soldering iron and vacuum gun. while I use 2 needle nose pliers
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