Hafler DH-110 manual Proper Soldering

There are three basic rules for success in electronic kit building:

1:Read the instructions carefully, and follow them in or- der.

2.Make secure solder connections which are bright and smooth .

3.Check your work carefully after each step.

The DH-110 preamplifier is a versatile component with sophisticated circuitry which has been made remarkably easy to build by individuals with many years of experience in the design and engineering of the finest performing audio kits, and in the preparation of their manuals.

Kit building should be fun, and we am certain you will find this to be so. Fatigue increases the risk of error, so take a break rather than push to early completion. There are relatively few separate components in this design, to make it easy to pack everything away, if need be.

Your work area should have good lighting	and the	proper
tools. The tools should include:
1 . A 40 to 60 watt pencil soldering iron with	a 3/16" or	smal-
ler tip which reaches 700°F

2.60/40 (60% tin) ROSIN CORE solder, l/16” diameter or smaller.

3.A damp sponge or cloth to wipe the hot tip of the iron.

4.A wire stripping tool for removing insulation. This can

be a single-edge razor blade, but inexpensive stripping tools are safer, faster and easier.

5.A medium-blade screwdriver (about l/4” wide).

6.Needle-nose pliers (a long, narrow tip).

7.Diagonal or side-cutting small pliers.

8.Large “gas” or “slip-joint” pliers.

9.A l/4” “Spin-tite” nut driver may be helpful, but is not necessary.

A soldering “gun” is not recommended. The unfamiliar user is more likely to damage the etched circuit boards with its higher heat potential and unbalanced weight. Also,

because he may not wait long enough for it to reach operat- ing temperature each time it is switched on, poor solder connections are more likely. Pencil irons are much lighter and easier to use, and there is no waiting time when solder connections follow in sequence, as in kit building. Make sure you have a holder for it, though, and always unplug it when you take a break.

Proper Soldering

There are four steps to make a good solder connection:

1 . Make a good mechanical connection to hold the wire in position while heat and solder is applied.

2 . Heat the junction of the wire and lug, or eyelet, with the bright, shiny tip of the iron.

3.After heating for a couple of seconds, apply solder to the junction. It should melt immediately and flow smoothly around both surfaces.

4.Allow the connection to cool undisturbed.

Remember that the connection is made by the solder, not by mechanically attaching the wire to the terminal. Usually the wire is looped through the lug and crimped in place, but some prefer to just place it through the hole and rely on the stiffness of the wire to hold it while soldering. Eyelet connections, of course, are handled this way.

Good solder connections are essential for trouble-free, noise-free operation. A good solder joint does not require much solder around the conductors. Never “butter” par- tially melted solder on the joint, as it is useless. A good connection looks smooth and bright because the solder flows into every crevice when the parts am hot enough. The iron must have a bright, shiny tip to transfer heat eas- ily to the junction. That’s why the damp sponge should be used frequently to wipe the tip, and occasionally you must add a small amount of solder to the tip, too. If a connection is difficult to heat, “wet” the tip with a small blob of solder to provide a bigger contact surface to the joint. Once the solder flows around the conductors, any movement must be avoided for a few seconds to allow a good bond. When cool, check the connection by wiggling the wire. If in doubt, or if the connection is not shiny, m-heat the joint.