I got a replacement preamp for one that went bad. It has a small circuit board which needs a battery lead soldered to one tiny little point on it. Looks really delicate and I tend to burn everything in sight when I have a soldering iron. This is weird because I'm really skilled with almost all other tools. Got any tips?
There have been some good threads/advice about soldering on here, and YouTube has all the info you need (and maybe some you don't).
With some help from YouTube, this should be really easy to do. However, if you are worried about it, find the local PA shop. They always have a bench guy that's making mic cables, snakes, adapter cables, etc. He'll be good at it (unless he gets totally sick of it like I did). If you haven't invested in (good) soldering gear, and you don't otherwise plan to solder anymore once this project is done, it would be worth a few bucks to the bench guy to fix you up.
get yourself a pot of coffee (or a six pack, whatever), sit down and watch this complete series on soldering; it's long and slow, but it'll answer all your questions about how solder actually works. it's transformed my own soldering techniques.
A common mistake is to use the iron to melt the solder while the tag/wire/track you're dealing with is not hot enough. Use the iron to heat the object and let its heat melt the solder. Use the right size iron and tip for the job. A little solder on the tip will allow a greater area of contact between it and the object and so better heat transfer. And please don't suck - use a solder sucker.
I started soldering this year. A good iron and utilizing Flux really keeps it under control! I notice that my 15 watt solder iron really messed me up. It took longer to heat up the solder. Went back to the store and bought a solder gun with 2 settings 50 or 100 watts. Made it a lot easier. I notice that the flux I use really keeps it clean and quick.
Use very then solder and a small tip 25-30 watt iron. Make sure to clean tip on on the iron with the wey foam pad. Try to get on and of as quickly as possible to not over heat the board
I taught myself to solder by watching some videos, as others have suggested. Before I touched my bass, though, I found some old/broken/useless electronic components and did a bunch of practicing until I felt confident enough to do the real job.
Or find a neighbor high school or college kid that's into engineering. Don't practice on something you might fry. Practice on old junk computer boards or something like that. I can't strees enough about getting a good iron. The hardware store ones suck IMO. Some people pride themselves on how long they can use a $15 iron, sort of like a badge of honor amongst certain DIY'ers. If this is a once-only type of deal, find someone. If this is going to be a regular thing, invest in a high quality solder station with variable heat.
It's just like brazing (a form of welding). On parts like that, the important thing is to never get your work (what you are soldering) too hot. Less heat, the better. But, make sure it bonds well. There's a thin line between too muck and too little.
Youtube was how I taught myself, but I would say get a decent quality iron ($30-50 should get the job done) and just practice soldering wires together. Pick up some cheap pots or whatever and practice soldering wiring to those. Get an old PC board and practice soldering stuff onto there as well. You can watch videos all day long, but you'll need to get a feel for it before you can be truly effective. Several preamps, a few circuit boards, and some random tidbits later I'm pretty confident in my abilities. Do NOT cheap out on the iron! First one I used had a chunk melt out of it, cheap ones are cheap for a reason. Weller makes some awesome ones, I love mine.
variable temp iron with different size tips... having only one size tip is like only having only one size screw driver. it just won't work for some applications
Here is a discussion thread about soldering : http://www.talkbass.com/threads/tactics-of-the-soldering-masters.1009302/ Hope it helps.