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Soldering question

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thecheat:


--- Quote from: ChadTower on May 11, 2009, 11:31:04 am ---
That's not going to work well if he wants to keep soldering with this tip.  Good tips have a coating on them that make them easy to clean and slows the buildup of burned crud.  Once you have sanded that coating off you're guaranteeing the need to sand that tip after nearly every use.  Sandpaper is really only a good route on a trashed tip like you have - I learned this by trashing a couple of good tips myself thinking I was cleaning them.

--- End quote ---

I was more referring to the base of the tip where it contacts the steel shaft of the iron. Of course he should have a properly cleaned and tinned tip but if the base of the tip is oxidized, there won't be good heat transfer at all. Since he has a 25w pencil iron, it is likely that he might have a cheap tip that might need some touching up.

ChadTower:


Yeah, especially if he has a set screw type.  I had one of those and the screw didn't hold it all that flush against the element.  The screw on tips are better about that since the thread provides so much surface area for heat transfer.

The ironic part is that I keep seeing guys start on controller hacks because "it's a small easy job".  The truth is that these controllers are using small logic circuits that are fragile to soldering.  The item iself may be low risk but the job is not a simple one for beginners.  Learning to solder is a lot easier on something older like a VCR motherboard - and who can't get a free dead VCR these days?   ;D

thecheat:

I thought about doing a keyboard hack, gamepad hack, then I just sucked it up and bought an I-PAC. The money spent on a purpose-built interface was "cheaper" than time spent forcing something to work and continuing to have to mess with it, ultimately doing it over the right way again. When buttons get pushed, and joysticks get moved, I don't want to have to second guess if the ports have swapped, etc... just want it to operate as it should.

Back on topic, there are a ton of soldering kits for sale, check JDR Microdevices and Jameco.. (JDR.com, jameco.com) for pretty cheap.. they teach soldering, schematic reading, troubleshooting, etc. Good way to start out before moving on to more expensive or small (0605 SMT LEDs, anyone?) components.




MattM:

thecheat, Chadtower and richms: the traces are more of a gold colour than orange, so I guess that might be the issue. Never thought about that. Tinning the wires is no problem at all, so I don't think it's the iron's power or a dodgy tip. Bu then, it's not like I know a lot about these things. Oh, and I chose to do a gamepad hack because I wanted to see if I could make something more so than just having an arcade controller. If I ever make an actual cab though, I'll be thinking about an I-PAC, for the reasons thecheat stated.

As a general update, my uncle came around and helped me out. This kind of stuff, including soldering, was his area of study. To tin the traces (one of the few I hadn't killed :)), he laid the iron on them and then touched the solder to the tip of the iron to melt it and then ran the iron along the trace, 'painting' on the solder as it went. I tried it out after him and once I did that, and soldered on the wires, I plugged the PCB into the computer via it's USB cable. I touched the wires from the trace I soldered to together and they registered as button presses.

Now I'm no less confused, as I was under the impression that this was the wrong way to solder and would cause a cold joint that wouldn't work. My uncle reassured me that this was not the case. I've come across a video where it looked as if the guy was using this same method. It's this one:


Needless to say, I don't know what's going on.    :-[





thecheat:

That method is "cheating" but it works :) If your solder joints are shiny and flat on traces and are conical shaped on thru-hole joints, all is well. If the solder is a dull bubble, it's a cold joint.

The tricky bit is getting the trace or joint to be at least as hot as the melting point of the solder. That's why lead based solder is easier to work with, lower melting point. If you melt a bit of solder on the tip, it helps the heat transfer and acts like a catalyst.

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