How to desolder?

[gcedillo]

Hi guys this evening while installing a servo I cut the wire of one of them.
I have another servo wich is broken and was thinking about just changing the wires, maybe a silly question but I don`t know a thing of electronics.
My servos are futaba 3004.
Thanks again and sorry for the silly question. :)

[Rodney]

Did you cut all three wires or just one of them? Either way, it is just a simple solder job to join them back together, the problem being keeping them all the same length so there isn't an unsitely joint int the wire. If you only cut one, it might be better to cut the other two as well and the strip and join the wires so all are the same length. While cut (not reconnected) slip some heat shrink tubing over the ends of each wire so that it can be pulled over the finished joint and insulate it from all others. Be sure to use electronic grade solder, no acid based flux.

[gcedillo]

Thanks I`ll get heat shrink tubes and what kind of solder I have.

[Blackhawk3D]

You should use rosin core solder if that was meant as a Q.

[TimAuton]

For desoldering wires I like desoldering braid. It's a bit more controlable than a solder sucker. Get some flux too and coat the braid before you use it, it should be able to suck all the solder out of the joint so a gentle pull on the wires is enough to remove them.

If you're re-working solder joints it's MUCH better to remove the old solder and re-solder with fresh stuff. Just melting an existing blob of solder and sticking a wire in will result in a very poor joint.

Finally, if you're not very good at soldering you tend to take longer over each joint than when you are more experienced. This introduces the danger of overheating the components. If your joint isn't working after 5 seconds or so STOP, let it cool and try again. If the solder doesn't flow that quickly either your iron isn't hot enough, the tip is too dirty to conduct the heat or the joint isn't clean enough for the solder to wick (so clean it and apply flux).

[Ledbetter]

I have a couple of servos in the same condition. Any tips on joining two tiny wires without making a bulge?

[Rodney]

For wires like in a servo, make a jig using two snap clothepins and a piece of wood, something like a pop sickle stick. Bare (strip off the insulation) from about a 3/16 to 5/16 inch of each wire to be joined. Put some rosin core flux on the wire and tin each piece to be joined. Tinning is just putting a thin coating of solder on the wire. Now, using a snap clothes pin or similar clamp, position the tinned wires side by side just touching each other. Make sure they wont move if a little pressure from the solder or soldering iron gently touch them. Now heat the wires where they are touching each other, usually no more solder is required, that put on when they were tinned is usually plenty. You will see the solder flow together from the two wires where they touch. Remove the heat and do not move the wires until they have slightly cooled, takes just a few seconds. You do not have to make a good mechanical joint first as the solder will hold the wire together quite reliably. The main thing to create a good solder joint is to have the wires very clean and do not let the joint move while it is cooling. If you are going to use heat shrink as an insulation when done, don't forget to put it over the wire before soldering and keep it far enough away from the joint so it doesn't shrink up around the wire while you are trying to solder it. When the joint cools, slide the heatshring over the joint and heat it with you covering gun if you have one. If not, carefully hold the hot soldering iron near the heatshrink to shrink it on tight.

[Ledbetter]

Thanks friend, very helpful directions.

[ZAGNUT]

Rodney's method for splicing wires is the right way to do it but i like to poke each one into some solder paste before tinning and again before joining them together. makes for a nicer joint without any blobs where the iron is pulled away. and instead of a jig to hold the wires i put the iron in a vise and hold the wires in my hands.


dave

[tve]

check this out....
http://www.rcgroups.com/forums/showpost.php?p=4100648&postcount=44