Troubleshooting Soldering: My Experience with a 25W Iron

[Rive]

The wires were a bit tarnished, but they were too twisted for me to rub them with a sand paper. I kind of dipped the joints into flux. The result was this:

It is hard to 'repair' a tarnished wire. I suggest to give up on them at the start: most of the time it is just better to cut it shorter and strip it again.
This 'result' won't give a good example. I can tell that the soldering iron is burning hot (the insulation of the wire on the top got burned), the flux is burnt as well - but for a tarnished wire (and oxidized component legs) it is not really about your skill.

Try to tin the wire on the photo in #34 and post a picture of that.

 

[Wrichik Basu]

Try to tin the wire on the photo in #34 and post a picture of that.

I tried to tin that one, but it was too thick for my 25W soldering iron to handle. So I picked up a thinner wire of the same quality. After trying a few times, this is the best I got today:

I won't say that it is good when compared to something done by a professional. There is some cold solder near the bottom, which I couldn't prevent even after putting flux paste. Perhaps more practice is needed on my side.

In addition, here is a better picture of the tip of the soldering iron (the pictures posted previously in this thread were perhaps of not a good quality):

 

[Rive]

After trying a few times, this is the best I got today:

As long it is just an occasional soldering what does not matter much (low voltage, low current, no responsibility), then it is passable.
However: the insulation is still damaged, long up from the stripped part: the surface is uneven, the flux is burnt brown. Won't pass anywhere where it really matters.
I don't think this will be much better later on. To heat up the wire at 25W you really need the high temperature, but with a high temperature iron it is really difficult to spare the insulation and the flux.

Link the process on a 4mm² wire with an old and battered Weller WSP-80 80W soldering iron @360°C (!).
Still not perfect, but the flux kept fresh (yellow), the surface is nice shinny and the insulation is intact.
Could have been faster but the magnifying glass was in the way.
I still suggest to get a better soldering iron.

 

[Wrichik Basu]

I still suggest to get a better soldering iron.

Yeah absolutely, I know that I won't be able to go far with this 25W. I will be buying a better one next month or so.

In your video, the wire brilliantly absorbs the solder. In my case, the solder doesn't melt unless I touch it near the tip of the iron. Temperature issue, of course.

By the way, I tried using this iron on a faulty pcb that I had. It could desolder the joints, and re-solder them as well (except the joints of the IC). Maybe those joints required lower temperature, so this iron could do it.