Elenco 23 Range 20k/V VOM in Kit Form - Manual (Page 4)

Introduction
Assembly of your M-1250 Analog Multimeter Kit will prove to be an exciting
project and give you much satisfaction and personal achievement. If you
have experience in soldering and wiring techniques, then you should have
no problem with the assembly of this kit. Care must be given to identifying
the proper components and in good soldering habits. Above all, take your
time and follow these easy step-by-step instructions. Remember, “An
ounce of prevention is worth a pound of cure”. Avoid making mistakes and
no problems will occur.
CAUTION: WEAR SAFETY GLASSES WHEN ASSEMBLING
THIS KIT.
Safety Procedures
• Wear eye protection when soldering and during all phases of this kit.
• 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 and the board is turned to solder the component leads
on the foil side. Solder immediately unless the pad is adjacent to another
hole which will interfere with the placement of the other component. Cut
excessive leads with a diagonal cutter. Then, place a check mark in the box
provided next to each step to indicate that the step is completed. Be sure
to save the extra leads for use as jumper wires if needed.
Soldering
The most important factor in assembling your Analog Multimeter 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. Many areas on the PC board are close together and care
must be given not to form solder shorts. Size and care of the tip will
eliminate problems.
For a good soldering job, the areas being soldered must be heated
sufficiently so that the solder flows freely. Apply the solder
simultaneously to the component lead and the component pad on the PC
board so that good solder flow will occur. Be sure that the lead extends
through the solder smoothly indicating a good solder joint. Use only
rosin core solder.
DO NOT USE ACID CORE SOLDER! Do not blob the solder over the
lead because this can result in a cold solder joint.
-3-
CONSTRUCTION
1. Solder all components from the
copper foil side only. Push the
soldering iron tip against both the
lead and the circuit board foil.
Component Lead Soldering Iron
Circuit Board
Foil
Example 1
Poor solder connections occur when
the lead is not heated sufficiently. The
solder will not flow onto the lead as
shown. To correct, reheat the
connection and, if necessary, apply a
small amount of additional solder to
obtain a good connection.
Solder does not flow onto the lead. A hard
rosin bead surrounds and insulates the
connection.
Poor solder
connection
Soldering iron positioned incorrectly.
Example 2
A solder bridge occurs 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 solder bridge as shown.
4. Here is what a good solder
connection looks like. Cut off excess
leads.
Mount Part Bend Leads to Hold Part Solder & Cut Off Leads
Foil Side
Rx - 100 Ω 5% 1/4W Resistor
(brown-black-brown-gold)
2. First 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.
Solder Soldering Iron
Foil
3. Allow the solder to flow around the
connection. Then, remove the
solder and the iron and let the
connection cool. The solder should
have flowed smoothly and not lump
around the wire lead.
Solder
Soldering Iron
Foil
IDENTIFYING RESISTOR VALUES
Use the following information as a guide in properly identifying the
value of resistors.
IDENTIFYING CAPACITOR VALUES
Capacitors will be identified by their capacitance value in pF
(picofarads), nF (nanofarads), or
μF (microfarads). Most
capacitors will have their actual value printed on them. Some
capacitors may have their value printed in the following manner.
1 2 Multiplier
Tolerance
BANDS
Second Digit
First Digit
Multiplier
Tolerance
103K
100V
Maximum
Working Voltage
The value is 10 x 1,000 = 10,000pF or
.01
μF 100V
The letter M indicates a tolerance of +20%
The letter K indicates a tolerance of +10%
The letter J indicates a tolerance of +5%
Note: The letter “R” may be used at times
to signify a decimal point; as in 3R3 = 3.3
Multiplier
For the No. 0 1 2 3 4 5 8 9
Multiply By 1 10 100 1k 10k 100k .01 0.1