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CONSTRUCTION
Introduction
The most important factor in assembling your M-2666 Digital Multimeter Kit is good soldering techniques. Using
the proper soldering iron is of prime importance. A small pencil type soldering iron of 25 - 40 watts is
recommended. The tip of the iron must be kept clean at all times and well tinned.
Safety Procedures
• Wear eye protection when soldering.
• Locate soldering iron in an area where you do not have to go around it or reach over it.
• Do not hold solder in your mouth. Solder contains lead and is a toxic substance. Wash your hands
thoroughly after handling solder.
• Be sure that there is adequate ventilation present.
Assemble Components
In all of the following assembly steps, the components must be installed on the top side of the PC board unless
otherwise indicated. The top legend shows where each component goes. The leads pass through the
corresponding holes in the board and are soldered on the foil side.
Use only rosin core solder of 63/37 alloy.
DO NOT USE ACID CORE SOLDER!
What Good Soldering Looks Like
A good solder connection should be bright, shiny,
smooth, and uniformly flowed over all surfaces.
1.
Solder all components from
the copper foil side only.
Push the soldering iron tip
against both the lead and
the circuit board foil.
2.
Apply a small amount of
solder to the iron tip. This
allows the heat to leave the
iron and onto the foil.
Immediately apply solder to
the opposite side of the
connection, away from the
iron.
Allow the heated
component and the circuit
foil to melt the solder.
3.
Allow the solder to flow
around
the
connection.
Then, remove the solder
and the iron and let the
connection
cool.
solder should have flowed
smoothly and not lump
around the wire lead.
4.
Here is what a good solder
connection looks like.
Soldering Iron
Component Lead
Foil
Circuit Board
Soldering Iron
Solder
Foil
Soldering Iron
Solder
Foil
The
Types of Poor Soldering Connections
1. Insufficient heat - the
solder will not flow onto the
lead as shown.
2. Insufficient solder - let the
solder
flow
over
connection
until
covered. Use just enough
solder
to
cover
connection.
3. Excessive solder - could
make connections that you
did not intend to between
adjacent
foil
areas
terminals.
4. Solder bridges - occur
when solder runs between
circuit paths and creates a
short circuit. This is usually
caused by using too much
solder.
To correct this,
simply drag your soldering
iron
across
the
bridge as shown.
-7-
Rosin
Soldering iron positioned
incorrectly.
Solder
the
it
is
the
Component Lead
Solder
or
Soldering Iron
solder
Foil
Gap
Drag
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