from the marvin3m guide:
1b. Before Beginning: How did you learn to solder?
Soldering a new coil in a game is one thing. A sloppy job won't really affect much. Sloppy soldering on a circuit board is another matter however. A circuit board can be totally ruined with bad soldering. Also the equipment and techniques are a bit different on circuit boards than on coils.
I remember when I first learned to solder. My dad taught me with a soldering pencil, some paper clips, and some rosin core solder. I was probably 10 years old, and I thought it was fun! What he had me do first was make a box out of the paper clips. Using needlenose pliers, I constructed one side of the three dimensional box. Then I soldered the points where the paper clips came together. When I was done, it was a pretty nifty 3-D box, and I was proud.
Nostalgia aside, this was a good first experience. It taught me how to solder, at the expense of only some paper clips. If one has novice soldering skills, start small and practice! Sacrifice some paper clips and make a "box".
--------------------------------------------------------------------------------
1b. Before Beginning: Practice makes Perfect.
If a pinball machine is in the future plans, then the owner needs to know how to solder! Knowing how to do basic soldering of wires onto solenoids (coils) and switches is a must. Due to the vibration of solenoids and players in a pinball machines, wires do break off coils and switches. It happens, and the owner will need to know how to deal with it!
Basic soldering is pretty straight forward. Get a soldering station and some good quality solder (as decribed below). Having the right tools is 75% of the job! And remember, a good solder job on a coil or switch starts with a good *mechanical* connection. That is, the wire should be mounted to the coil or switch lug before being soldered, and stay put! After that, soldering the wire is just a matter of heating the wire and the lug *together*, and then applying a small amount of solder. The solder should be applied to the wire or lug, and *not* directly to the soldering iron's tip. This ensures the solder will flow over the wire and the lug, and that they are heated to the right temperature. The soldering iron can then be removed from the joint. Now keep the solder joint steady while it cools, otherwise it could produced a "cold" solder joint (one that does not conduct electricity freely).
Once this basic soldering is mastered, the next step (maybe!) is solder on a Printed Circuit Board (PCB). If one has never soldered a PCB before, don't try your first attempt on a (expensive!) pinball CPU or Driver board! Practice on some junk boards first.
Junk circuit boards are easy to get. Video game collectors can often provide some junk JAMMA games board or other boards. Maybe there's an old PC computer (which you couldn't give away!) that's could be used. Practice circuit boards aren't that hard to find. You just gotta look. Even if one has to pay for some junk boards, it's well worth it.
Another alternative is to go to Radio Shack and buy some cheap resistors (about 50 cents for five), and some "breadboard" print circuit board material with holes, part number 276-150 at $1.19, or part number 276-168 at $2.49. Practice soldering the resistors to the board. This is not as good practice as using a real printed circuit board though (there's nothing like the real thing). Remember to clean the copper on the Radio Shack board with some Scotchbrite before trying to solder them (unsoldered virgin copper likes to oxidize, making soldering difficult). But please read the tips and info below before starting.