Unsoldering 'reef knots' ...? - Page 1
Forum section: electronics / beginners

author: jaunty
author_rank: Regular Contributor
timestamp: September 20, 2018, 02:40:52 am
content: 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?

author: tkamiya
author_rank: Super Contributor
timestamp: September 20, 2018, 03:05:29 am
content: 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)

author: Brumby
author_rank: Unknown
timestamp: September 20, 2018, 03:16:22 am
content: 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.

author: jaunty
author_rank: Regular Contributor
timestamp: September 20, 2018, 04:06:18 am
content: 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!!

author: Raj
author_rank: Frequent Contributor
timestamp: September 23, 2018, 05:02:17 pm
content: I would have brought in a helper to operate soldering iron and vacuum gun. while I use 2 needle nose pliers

author: jaunty
author_rank: Regular Contributor
timestamp: September 25, 2018, 06:02:09 am
content: ack - too many handsi gave up after a while and decided it was far more effective to just cut the wires and resplice later

author: Brumby
author_rank: Unknown
timestamp: September 25, 2018, 06:13:16 am
content: Annoying - but far less frustrating.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: September 25, 2018, 07:08:28 am
content: Lots of flux, a chisel tip iron, solder sucker, and quality desoldering braid.Start by flowing an excess of fresh solder onto the joint you're trying to de-solder. Old solder is a pain to do anything with, so wetting the joint thoroughly with fresh lead solder is an important first step.Next, use the solder sucker to remove as much of the excess solder as you can.Finally, daub a bunch of Rosin based flux onto the joint and the braid. Apply the braid and the iron, and the braid should absorb the rest of the solder.I've used this technique for many years, and it works even with multi later boards, as good wick will suck the joint completely dry.Edit: Make your iron just hot enough to melt the solder, so that your flux doesn't boil away too quickly. More heat isn't necessarily good in this situation.Sent from my ONEPLUS A3000 using Tapatalk