Vectronics VEC-820K - Manual (Page 4)

V EC-820K Instruction Manual CW Filter
BEFORE YOU START BUILDING
Experience shows there are jour common mistakes builders make. Avoid these.
and your kit will probably work on the first try! Here's what they are:
1. Installing the Wrong Part: It always pays to double-check each step. A 1K and
a 10K resistor may look almost the same, but they may act very differently in
an electronic circuit! Same for capacitors--a device marked 102 (or.001 uF)
may have very different operating characteristics from one marked 103 (or
.01uF
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. Always double-check--especially before applying power to
the circuit!
3. Faulty Solder Connections: Inspect for cold-solder joints and solder bridges.
Cold solder joints happen 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
allow 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, wetting all exposed surfaces. Apply solder
sparingly, and do not touch solder directly to the hot iron tip to promote rapid
melting.
Desoldering Tips: If you make a mistake and need to remove a part, follow these
instructions carefully! First, grasp the component with a pair of 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.