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Discussion Starter #1
I recently installed a DP and had to solder together the 4 wires for a new O2 sensor... This was while the vehicle was on jack stands... and under the car... so basically i'm working with my arms above my head trying to solder from the bottom...

I basically had to hold the solder above the wires and hope it was "driping" down where it should be.. i tried turning them over and doing both sides... bla bla bla... best I could manage in the dark and under the vehicle (I had a light.. but wasn't great)...

I'm no expect in soldering.. however just to test I went out and soldered a few wire ends together to make sure I wasn't retarded... had no troubles... So it is just really hard to do? Or are there some tricks to soldering that Would have helped me more?
 

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I always keep the wire I am soldering between the iron and the solder. That help prevent a cold solder connection and it ensures the solder evenly coats the exposed wire.
 

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Discussion Starter #3
You mean.. heating the wires.... enough to melt the solder? I've tried this.. however I often find that either A) the heat source isn't enough to heat the wires and melt the solder.. or B) the wires are made out of something that doesn't conduct the heat well enough (sounds odd I know)...

However in this situation... I was holding everything above my head ... and the heat source wasn't much... so it took quite a while to get it done... trying to heat the wires would have taken even longer... but might have been a more clean install...

Also... Getting the wires to stay together for soldering is another PITA... I usually split them in half on each end.. and twist them together. then mash the 2 larger twists together and start to solder... Seems like the best easiest way to get a connection and keep them together for the solder..
 

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Yes, I do mean heating the wires enough so the solder melts. (Though sometimes you do have to start the solder melting on the iron and then use the heat that is transfered to the wires to keep it going.)

If you can't heat the wires enough to keep the solder flowing, you probably don't have the correct size tip on your iron (for example: a tiny 15W needle tip for surface mount work on circuit cards; a general purpose 45W small tip for all-around work; and a 80W plug-tip monster for chassis soldering and heavy wire).

To keep the wires together, I also twist them together. If that doesn't hold, then you could try some forceps to clamp them together while doing the soldering.

Also, it is recommended to only use enough solder to make the connection. This means that you should be able to see the wires with a coating of the solder, not just a glob connecting the wires together.
 

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Usually you can get just a bit on the end of your iron and wipe it onto the wires... But man becareful cuz hot solder going down your arm hurts like hell... HEHE
 

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Usually you can get just a bit on the end of your iron and wipe it onto the wires... But man becareful cuz hot solder going down your arm hurts like hell... HEHE
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Applying solder like that is probably the best way to get a cold solder joint. I know I wouldn't trust a connection done like that, especially for something like an O2 sensor. Just FYI
 

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My background is in electronics and I've literally soldered 10's of thousands of joints, both on cct boards and wires. Here are a few tips to ensure easy soldering and good solder flow:

1. Make sure the wires will readily accept solder. Try applying a bit of solder to each wire tip. If the solder doesn't seem to want to flow on to the wire, take a bit of sandpaper to the wire and expose fresh metal. Sometimes bare wires can have a microscopic coating (such as oxidation or left over compounds from the insulation) that impedes solder flow. Sanding removes this layer.

2. Use solder with a rosin flux core. If you only have solid core solder get some rosin flux (it's usually available as a thick paste in a small can). Apply flux to the joint being soldered. This helps clean the joint and the solder to flow easier. Don't get the acid flux. That's the wrong stuff for electrical connections.

3. Twist the wires together well. You want a strong, tight mechanical joint so only a little solder needs to flow in to lock it all together.

4. Heat up the wires with the soldering iron tip. The surfaces being soldered have to be almost the same temperature as the soldering iron tip so that the solder flows easily. You need to be able to press the soldering tip against the joint with a bit of pressure to get the heat to transfer. This might mean creating a surface to bear against, or, as in 3, making sure the joint is strong so you can apply a bit of pressure to get heat transfer without the joint coming apart.

5. Clean and pre-tin the tip of your soldering iron. Use a wet rag to clean the tip after it's reached operating temperature. Apply some solder to the tip so that it's nice and shiny. Clean again. The tip should now be ready to go. Again, if you don't have rosin core solder apply some flux too.

6. When everything is ready to go, apply heat to the joint with the soldering iron tip. Wait for it to heat the joint up, then apply the flux and the solder to the point where the tip is touching the joint. Rosin core solder make this much easier as you can do it in one step. The solder should melt almost immediately and flow into the joint. Remove the tip and try not to disturb the joint as the solder is cooling. This will only take a few seconds to cool and become solid. Disturbing the joint will result in poor crystallization and a cold solder joint.


Following the steps above should get you a good strong soldered joint.
 

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^^^ Good write-up for basic soldering :thumbup: :thumbup:
 

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Discussion Starter #9
Yeah... A few things for my situation...

1) I need better heat source... the "classic" long skinny "marker" looking thing "works" but I don't think it provides enough heat to heat the wires up like you say... I was out testing this a day or two ago... i pressed wires against a cardboard box for up to 30 seconds.. and could not get the solder to melt on the wires... only when pressed against the tip of the heat source....

2) I was working upside down... under a car.. in the semi-dark... arms start to get tired.. twisting wires and holding things steady isn't an option really... I managed to get as much solder as possible to hold everything together... then used electrical tape to wrap each wire... and then the whole group of 4 when I was done...

3) The wires I was working with were not "easy" bend and stay... they resisted any movement or placement.... it was a PITA to twist them together... It seems like some types of metal used in wiring will move and bend exactly where you place it.. while others are very resistant... i would twist them together tightly and they'd almost pop back to the way they were...



Anyway... thanks for the writeup... I will try sanding the wires a bit next time that seems like a really good idea... I think the most difficult time I had / have when working in confined spaces soldering... is getting the liquid metal solder to detach from the heatsource and stay on the target... Seems like half the time when i try to coat the target.. it just balls up and stays with the heat source... I think the job got done either way though... much better than using stupid crimp wire connectors...

One thing i'm considering for future use.... The crimp connectors that usually come with a plastic cover... What I want to try is removing the plastic cover.. crimping the wires down.. and then placing solder in the tips and ends of the crimps... I think this will help make a solid connection and keep the wire in place better...
 

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Yeah... A few things for my situation...

1) I need better heat source... the "classic" long skinny "marker" looking thing "works" but I don't think it provides enough heat to heat the wires up like you say... I was out testing this a day or two ago... i pressed wires against a cardboard box for up to 30 seconds.. and could not get the solder to melt on the wires... only when pressed against the tip of the heat source....

2) I was working upside down... under a car.. in the semi-dark... arms start to get tired.. twisting wires and holding things steady isn't an option really... I managed to get as much solder as possible to hold everything together... then used electrical tape to wrap each wire... and then the whole group of 4 when I was done...

3) The wires I was working with were not "easy" bend and stay... they resisted any movement or placement.... it was a PITA to twist them together... It seems like some types of metal used in wiring will move and bend exactly where you place it.. while others are very resistant... i would twist them together tightly and they'd almost pop back to the way they were...
Anyway... thanks for the writeup... I will try sanding the wires a bit next time that seems like a really good idea... I think the most difficult time I had / have when working in confined spaces soldering... is getting the liquid metal solder to detach from the heatsource and stay on the target... Seems like half the time when i try to coat the target.. it just balls up and stays with the heat source... I think the job got done either way though... much better than using stupid crimp wire connectors...

One thing i'm considering for future use.... The crimp connectors that usually come with a plastic cover... What I want to try is removing the plastic cover.. crimping the wires down.. and then placing solder in the tips and ends of the crimps... I think this will help make a solid connection and keep the wire in place better...
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It sounds like the problem is more your soldering iron than anything else... the wires you can rubberband to a pencil, leaving the stripped wire expose, then following the normal steps... this usually holds it down. Ive had to do this in the past...

Also, try to use shrinkwrap instead of electrical tape, this may be a personal preference to some, but if you have to resolder, electrical tape leaves a sticky layer behind that requires you to either sand again, or cut and strip again. Shrinkwrap you can simply cut off, and has the same basic properties as electrical tape.

If you are looking for connectors, get powerpoles. They have the least resistance of any connectors available. Usually they are used in HAM radios, but they are practical for any electrical currents. I use them for just about anything. I forgot the site that has them, but they require no soldering and give, again, minimal resistance.
 
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