Vectronics VEC-1290K - Manual (Page 4)

BEFORE YOU START BUILDING
Experience shows there are four common mistakes builders commonly make.
Avoid these, and your kit will probably work on the first try!
1. Installing the Wrong Part: It always pays to double-check each step. A 1K
and a IOK resistor may look almost the same, but may act very differently in
an electronic circuit! The same is true for capacitors-a device marked 102 (or
.001 uF) may have very different operating characteristics from one marked
103 (or .01 uF).
2. Installing Parts Backwards: Always check the polarity of electrolytic
capacitors to make sure the positive (+) lead goes in the (+) hole on the
circuit board. Transistors have a flat side or emitter tab to help you identify
the correct mounting position. ICs have a notch or dot at one end indicating
the correct direction of insertion. Diodes have a banded end indicating correct
polarity.
3. Faulty Solder Connections: Inspect for cold-solder joints and solder
bridges. Cold solder joints occur when you don't fully heat the connection
or when metallic corrosion and oxide contaminate a component lead or
pad. Solder bridges form when a trail of excess solder shorts pads or
tracks together (see Solder Tips below).
4. Omitting or Misreading a Part: This is easier to do than you might think!
Always double-check to make sure you completed each step in an assembly
sequence.
Soldering Tips: Cleanliness and good heat distribution are the two secrets of
professional soldering. Before you install and solder each part, inspect leads
or pins for oxidation. If the metal surface is dull, sand with fine emery paper
until shiny. Also, clean the oxidation and excess solder from the soldering
iron tip to ensure maximum heat transfer. Allow the tip of your iron to
contact both the lead and pad for about one second (count "one-thousand-
one") before feeding solder to the connection. Surfaces must become hot
enough for solder to flow smoothly. Feed solder to the opposite side of the
lead from your iron tip. Solder will wick around the lead toward the tip,
i ll d f
Desoldering Tips: If you make a mistake and need to remove a part, follow
these instructions carefully! First, grasp the component with hemostats or
needle-nose pliers. Heat the pad beneath the lead you intend to extract, and,
pull gently. The lead should come out. Repeat for the other lead. Solder may