fini Posted April 6, 2011 Share Posted April 6, 2011 When you are removing a component (for example, a capacitor) from a circuit, what technique and precautions should one take, specifically with regard to situation where several components/wires are soldered at the same point? In my still-beginner soldering experiences, it can get tricky removing just that one wire, especially when it's been through a hole and wrapped around (along with all the others). My temptation would be to clip the wire long and solder the new component to the old component's lead. I'm guessing this technique is frowned upon by those who do quality work. It sure seems like it would be easier (and less messy). What do you think? Quote Link to comment Share on other sites More sharing options...
Brac Posted April 6, 2011 Share Posted April 6, 2011 So you don't own a sucker? http://www.amazon.com/Parts-Express-Solder-Sucker/dp/B0002KRAAG You wanna suck the solder right out, then put the new and re-solder. Quote Link to comment Share on other sites More sharing options...
fini Posted April 6, 2011 Author Share Posted April 6, 2011 Oh I have one, sucker. Oops, I mean, I have one sucker. [] I find that it gets a lot of the solder out of there, but doesn't remove enough to set the wires free. Quote Link to comment Share on other sites More sharing options...
Brac Posted April 6, 2011 Share Posted April 6, 2011 Sometimes you have to get the sucker on the opposite side from the heat. Sometimes they are just a PITA! What you working on? Quote Link to comment Share on other sites More sharing options...
Guest " " Posted April 6, 2011 Share Posted April 6, 2011 Thats the absolute best approach.....clip the lead close to the old componet....take a new componet and use a very small eyeglass screw driver and wrap the leads of the new componet into a few coils.....take a surgical clip and clamp the old lead close to the circut board to act as a heat sink...slide the new componet coil onto the old lead....solder quickly using a low heat soldering pencil. prevents the circut trace from coming off, and gets you a good repair. Quote Link to comment Share on other sites More sharing options...
fini Posted April 6, 2011 Author Share Posted April 6, 2011 Nothing right now, but I have a ton of pieces that need work. Seriously though, you are able to use the sucker, then pull out the component? I usually at a minimum need to be pulling on it with needle nose pliars while applying heat. Quote Link to comment Share on other sites More sharing options...
fini Posted April 6, 2011 Author Share Posted April 6, 2011 Speakerfritz, Most pieces I'd be working on are older, point-to-point wired (although of course the ST-70s have circuit boards). Same technique when it's soldered to a post? Quote Link to comment Share on other sites More sharing options...
cfelliot Posted April 6, 2011 Share Posted April 6, 2011 Sometimes a little solder flux paste or new solder added to the existing joint will make it easier for the sucker to clear the joint. Alligator clips make great heat sinks to protect other leads. Quote Link to comment Share on other sites More sharing options...
Guest davidness Posted April 6, 2011 Share Posted April 6, 2011 I use both a solder sucker and some solder wick. Link. I can't give you any advise as to what size of wick to use, I just use the one size I bought. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted April 6, 2011 Share Posted April 6, 2011 the traces on PCB are problematic....they come right off very easy...component cut off method. Tag boards have both terminals and eyelet pass thru holes....these are pretty easy and the above mentioned solder suckers and wicks work well. Sometimes you have a terminal with multiple components on it....desoldering becomes difficult as the heat needed to melt the solder on a multiple component connection can damage good components. I would use the cut off method for PCB boards and for multiple component connection terminals. keep in mind, once a trace comes off...now you need a jumper wire...and the problem expands. Quote Link to comment Share on other sites More sharing options...
Blvdre Posted April 8, 2011 Share Posted April 8, 2011 For multiple components soldered to a terminal, the problem is that, if the components were installed properly, there will be a strong mechanical connection to overcome as well. For instance, a cap lead wrapped around a terminal will have been "crimped", or secured, with a pair of needle nose in order to establish a solid mechanical connection before soldering. When removing these components, it's difficult to remove every last bit of solder. Using a sucker and following up with wick helps, but requires longish dwell times which heats up your other parts. My preffered method is to clip the old component out of the circuit (as Speakerfritz already recommeded), leaving just little bit of the lead still secured to the terminal. Heat the terminal and suck out as much solder as possible. Now grab your needlenose and grab on to the end of the remaining lead. Apply heat once more and pull the lead out while the solder is flowing. The dwell times required are short which will minimize the heat applied to the joint and other components. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted April 8, 2011 Share Posted April 8, 2011 Not all solder suckers are equal. I've had several that wouldn't hardly suck new out of the box. I seem to fall back on one of the oldest I have and that's one with heat and the sucker built into one unit. Also if you can move the soldered wire a little while sucking that can really help make the solder go. Quote Link to comment Share on other sites More sharing options...
fini Posted April 8, 2011 Author Share Posted April 8, 2011 JL, is this the desoldering tool you use? http://www.radioshack.com/product/index.jsp?productId=2062731 Quote Link to comment Share on other sites More sharing options...
Wrinkles Posted April 8, 2011 Share Posted April 8, 2011 fini, Another model is the soldapulit http://www.partsconnexion.com/tools-53660img.html I have used this for over 30 years. Teflon tip is replaceable should you melt it. I think I have replaced one tip in that thirty years. It comes apart to grease an oring that creates a seal when drawing the rquired vacuum. Only need to do this when it stops drawing the vacuum, easy twist and turn. They are $19.95 at parts express. The other models listed in this thread I have not used and I am sure are probably very capable. This is my 2 cents. Quote Link to comment Share on other sites More sharing options...
Wrinkles Posted April 8, 2011 Share Posted April 8, 2011 A quick read on soldering and desoldering techniques: http://www.uky.edu/~kdbrad2/Soldering_Desoldering.pdf Quote Link to comment Share on other sites More sharing options...
mike stehr Posted April 8, 2011 Share Posted April 8, 2011 My temptation would be to clip the wire long and solder the new component to the old component's lead. I'm guessing this technique is frowned upon by those who do quality work. It sure seems like it would be easier (and less messy). What do you think? There is no problem with doing that. Just leave enough of the old component's lead to make a little hook, and then make a little hook on the new component...crimp, and solder. After that, it would be wise to re-heat/reflow the solder at the pins of the socket, to make there is no old dry solder joints you may pass up. If you are doing a vintage tube amp rebuild, I wouldn't too concerned about overheated components. They will all pretty much need to be replaced, with some exceptions. The socket pins in old 45-50 year old tube amps can be pretty filthy, and one needs to pay attention to that. You do need to concern overheating when soldering new components in however. If I can afford it, I tend to try replacing the sockets with new ones. Or I'll look the pins over and clean them. Get a solder sucker and iron, go find find some scrapped tube amp in the pile, and practice on it. Use the sucker to get the majority of the solder, and if you want to save the sockets/pins, use the wick to clean them up. Quote Link to comment Share on other sites More sharing options...
WMcD Posted April 8, 2011 Share Posted April 8, 2011 I did some of this a long time ago. It is a real problem when the terminal has multiple wires connected to it. I clipped off the lead at the component. That way you have more access and you can get a solder sucker, or wick, in there plus the iron. Then you can use a needle nose on the long clipped off lead to push it through the hole in the terminal post.and unwind the winding of the lead around the terminal post from that end. Sometimes this has to be done with an iron applied. You can imagine the situation. It can be tough to find the far end of the original lead. But by clipping it, you can work the new, second end. WMcD Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted April 9, 2011 Share Posted April 9, 2011 Sorry to not get back sooner. Yes Fini, that is the one I prefer. Just got through replacing all the servo motors on my '05Tahoes instrument panel with one just like that. Worked great!. Quote Link to comment Share on other sites More sharing options...
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