RESISTANCE SUBSTITUTION BOX
MODEL K-37
Copyright © 2009, 2004 by Elenco®Electronics, Inc. All rights reserved. Revised 2009 REV-A 753400
No part of this book shall be reproduced by any means; electronic, photocopying, or otherwise without written permission from the publisher.
Elenco®Electronics, Inc.
Assembly and Instruction Manual
-1-
PARTS LIST
If you are a student, and any parts are missing or damaged, please see instructor or bookstore.
If you purchased this kit from a distributor, catalog, etc., please contact Elenco®Electronics (address/phone/email is at the back of this manual) for additional assistance, if needed. DO NOT contact your place of purchase
as they will not be able to help you.
RESISTORS
Qty. Symbol Description Color Code Part #
r 1R1 10Ω 5% 1/2W brown-black-black-gold 121001
r 1R2 22Ω 5% 1/2W red-red-black-gold 122201
r 1R3 47Ω 5% 1/2W yellow-violet-black-gold 124701
r 1 R4 100Ω 5% 1/2W brown-black-brown-gold 131001
r 1 R5 220Ω 5% 1/2W red-red-brown-gold 132201
r 1 R6 330Ω 5% 1/2W orange-orange-brown-gold 133301
r 1 R7 470Ω 5% 1/2W yellow-violet-brown-gold 134701
r 1 R8 680Ω 5% 1/2W blue-gray-brown-gold 136801
r 1R9 1kΩ 5% 1/2W brown-black-red-gold 141001
r 1 R10 2.2kΩ 5% 1/2W red-red-red-gold 142201
r 1 R11 3.3kΩ 5% 1/2W orange-orange-red-gold 143301
r 1 R12 4.7kΩ 5% 1/2W yellow-violet-red-gold 144701
r 1 R13 6.8kΩ 5% 1/2W blue-gray-red-gold 146801
r 1 R14 10kΩ 5% 1/2W brown-black-orange-gold 151001
r 1 R15 22kΩ 5% 1/2W red-red-orange-gold 152201
r 1 R16 33kΩ 5% 1/2W orange-orange-orange-gold 153301
r 1 R17 47kΩ 5% 1/2W yellow-violet-orange-gold 154701
r 1 R18 68kΩ 5% 1/2W blue-gray-orange-gold 156801
r 1 R19 100kΩ 5% 1/2W brown-black-yellow-gold 161001
r 1 R20 220kΩ 5% 1/2W red-red-yellow-gold 162201
r 1 R21 330kΩ 5% 1/2W orange-orange-yellow-gold 163301
r 1 R22 470kΩ 5% 1/2W yellow-violet-yellow-gold 164701
r 1 R23 680kΩ 5% 1/2W blue-gray-yellow-gold 166801
r 1 R24 1MΩ 5% 1/2W brown-black-green-gold 171001
MISCELLANEOUS
Qty. Description Part #
r 1 PC Board 517007
r 1 Switch SPDT PC Mount 541103
r 2 Switch 12 Position 542013
r 2 Knob 622009
r 1 Case with Cover 62RS400
r 4 Screw 4 x 1/2” Phil A 642465
r 2 Nut 9mm 644102
r 2 Washer 9mm x 15mm 645103
r 1 Alligator Clip Black 680001
r 1 Alligator Clip Red 680002
r 1 Wire Black Stranded 12” 814210
r 1 Wire Red Stranded 12” 814215
r 1 Solder Lead-free LF99
The Resistance Substitution Box is a convenient instrument in determining the desired resistance values in
circuits under design or test. The values selected for your resistance substitution box were determined to be
the most commonly used in modern solid-state circuits. The values are from 10Ω to 1,000kΩ (1 meg) in 24
steps. All resistors are 5% tolerance 1/2 watt.
-2-
PARTS IDENTIFICATION
Switch 12 Position
9mm Nut
Alligator Clip
Switch PC Mount
Resistor
Washer
IDENTIFYING RESISTOR VALUES
Use the following information as a guide in properly identifying the value of resistors.
BANDS
1
2 Multiplier Tolerance
PC Board
BAND 1
1st Digit
Color Digit
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9
BAND 2
2nd Digit
Color Digit
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9
Multiplier
Color Multiplier
Black 1
Brown 10
Red 100
Orange 1,000
Yellow 10,000
Green 100,000
Blue 1,000,000
Silver 0.01
Gold 0.1
Resistance
Tolerance
Color Tolerance
Silver ±10%
Gold ±5%
Brown ±1%
Red ±2%
Orange ±3%
Green ±0.5%
Blue ±0.25%
Violet ±0.1%
-3-
CONSTRUCTION
Solder
Soldering Iron
Foil
Solder
Soldering Iron
Foil
Component Lead
Soldering Iron
Circuit Board
Foil
Rosin
Soldering iron positioned
incorrectly.
Solder
Gap
Component Lead
Solder
Soldering Iron
Drag
Foil
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.
1. Insufficient heat - the solder will
not flow onto the lead as shown.
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.
4.
Here is what a good solder
connection looks like.
2. Insufficient solder - let the
solder flow over the connection
until it is covered.
Use just enough solder to cover
the connection.
3. Excessive solder - could make
connections that you did not
intend to between adjacent foil
areas or 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 solder
bridge as shown.
What Good Soldering Looks Like
A good solder connection should be bright, shiny, smooth, and uniformly
flowed over all surfaces.
Types of Poor Soldering Connections
Introduction
The most important factor in assembling your K-37 Resistance
Substitution Box 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.
Solder
For many years leaded solder was the most common type of solder
used by the electronics industry, but it is now being replaced by leadfree solder for health reasons. This kit contains lead-free solder, which
contains 99.3% tin, 0.7% copper, and has a rosin-flux core.
Lead-free solder is different from lead solder: It has a higher melting
point than lead solder, so you need higher temperature for the solder to
flow properly. Recommended tip temperature is approximately 700
O
F;
higher temperatures improve solder flow but accelerate tip decay. An
increase in soldering time may be required to achieve good results.
Soldering iron tips wear out faster since lead-free solders are more
corrosive and the higher soldering temperatures accelerate corrosion,
so proper tip care is important. The solder joint finish will look slightly
duller with lead-free solders.
Use these procedures to increase the life of your soldering iron tip when
using lead-free solder:
• Keep the iron tinned at all times.
• Use the correct tip size for best heat transfer. The conical tip is the
most commonly used.
• Turn off iron when not in use or reduce temperature setting when
using a soldering station.
•
Tips should be cleaned frequently to remove oxidation before it becomes
impossible to remove. Use Dry Tip Cleaner (Elenco
®
#SH-1025) or Tip
Cleaner (Elenco®#TTC1). If you use a sponge to clean your tip, then use
distilled water (tap water has impurities that accelerate corrosion).
Safety Procedures
• Always wear safety glasses or safety goggles to
protect your eyes when working with tools or
soldering iron, and during all phases of testing.
• Be sure there is adequate ventilation when soldering.
•
Locate soldering iron in an area where you do not have to go around
it or reach over it. Keep it in a safe area away from the reach of
children.
• Do not hold solder in your mouth. Solder is a toxic substance.
Wash hands thoroughly after handling solder.
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.
DO NOT USE ACID CORE SOLDER!
'
-4-
ASSEMBLY INSTRUCTIONS
Begin the PC board assembly with resistor R12. Be sure to identify the correct value by reading the color code.
Place the resistor into the PC board with the leads coming out on the copper foil side. Solder in place and clip
off the excess leads, close to the connection.
R12 - 4.7kΩ 5% 1/2W Resistor
(yellow-violet-red-gold)
R11 - 3.3kΩ 5% 1/2W Resistor
(orange-orange-red-gold)
R10 - 2.2kΩ 5% 1/2W Resistor
(red-red-red-gold)
R8 - 680Ω 5% 1/2W Resistor
(blue-gray-brown-gold)
R7 - 470Ω 5% 1/2W Resistor
(yellow-violet-brown-gold)
R9 - 1kΩ 5% 1/2W Resistor
(brown-black-red-gold)
R1 - 10Ω 5% 1/2W Resistor
(brown-black-black-gold)
R2 - 22Ω 5% 1/2W Resistor
(red-red-black-gold)
R3 - 47Ω 5% 1/2W Resistor
(yellow-violet-black-gold)
R5 - 220Ω 5% 1/2W Resistor
(red-red-brown-gold)
R6 - 330Ω 5% 1/2W Resistor
(orange-orange-brown-gold)
R4 - 100Ω 5% 1/2W Resistor
(brown-black-brown-gold)
R19 - 100kΩ 5% 1/2W Resistor
(brown-black-yellow-gold)
R20 - 220kΩ 5% 1/2W Resistor
(red-red-yellow-gold)
R21 - 330kΩ 5% 1/2W Resistor
(orange-orange-yellow-gold)
R23 - 680kΩ 5% 1/2W Resistor
(blue-gray-yellow-gold)
R24 - 1MΩ 5% 1/2W Resistor
(brown-black-green-gold)
R22 - 470kΩ 5% 1/2W Resistor
(yellow-violet-yellow-gold)
R18 - 68kΩ 5% 1/2W Resistor
(blue-gray-orange-gold)
R17 - 47kΩ 5% 1/2W Resistor
(yellow-violet-orange-gold)
R16 - 33kΩ 5% 1/2W Resistor
(orange-orange-orange-gold)
R14 - 10kΩ 5% 1/2W Resistor
(brown-black-orange-gold)
R13 - 6.8kΩ 5% 1/2W Resistor
(blue-gray-red-gold)
R15 - 22kΩ 5% 1/2W Resistor
(red-red-orange-gold)
-5-
r SW3 - PC Mount Switch
Mount SW3 in the place shown on the PC board.
Solder into place.
r Red Test Lead
r Black Test Lead
Cut off 1 1/2” of wire off of both the red and black
wires (SAVE them for later use). Strip 1/4” of
insulation off both ends of the 10 1/2” red and black
wires and insert them into the holes as marked on
the PC board. Solder into place. Tie a knot with
both wires 1 1/2” from the surface of the PC board
as shown in Figure 1. Pull the wires through the
hole in the cover. Slide the alligator boots onto the
wires. Solder the wires to the alligator clips. Then,
slide the boots onto the clips.
r SW1
r SW2
Bend the tab on the switches
down (see Figure 2). Attach the
two switches loosely to the front
panel with the 9mm nuts and
washers. Line up the holes of
the PC board with the switch
lugs, as shown in Figure 3. Be
sure that the board lays flat,
then solder the lugs into place.
Tighten down the 9mm nuts.
r Jumper wire from SW1
r Jumper wire from SW2
Strip 1/4” of insulation off of both ends of the 1 1/2”
red and black wires. Solder one end of the wire to the
wiper pin on the 12 position switches and the other to
the pad without a hole, as shown in Figure 4.
r Installation of Knobs if an Ohmmeter is Available
Place the knobs loosely on the switch posts. Push
the slide switch to the “Ω” position. Connect an
ohmmeter to the output. Line up the pointer of the
knob with the value shown on your meter, then push
the knob onto the shaft. Push the slide switch to the
“KΩ” position and repeat the same procedure.
Figure 4
SW1
SW2
Wiper Pin
Wiper Pin
Jumper Wires
Figure 3
9mm Nut
Washer
Cover
Figure 2
Bend Tab Over
PC Board
Figure 1
Bend Tabs
Over Wire
-6-
r Installation of Knobs without an Ohmmeter
If an ohmmeter is not available, turn both switches
so that the wiper contact is in the position shown in
Figure 5. Start with switch SW1, follow the copper
run on the PC board from the lug in contact with the
wiper to the 470Ω (R7) resistor, to be sure that the
switch is set in the proper position. Align the knob
on the SW1 (Ω) switch to the 470 position, push the
knob onto the shaft. Follow the same procedure for
switch SW2 (KΩ), except follow the copper run to
the 6.8KΩ (R13) resistor. Align the knob on the
SW2 (KΩ) switch to the 6.8 position.
TESTING THE CIRCUIT
SCHEMATIC DIAGRAM
SW1 Ω POSITION
Value Position Meter Reading
10Ω
22Ω
47Ω
100Ω
220Ω
330Ω
470Ω
680Ω
1000Ω
2200Ω
3300Ω
4700Ω
SW2 KΩ POSITION
Value Position Meter Reading
6.8KΩ
10KΩ
22KΩ
33KΩ
47KΩ
68KΩ
100KΩ
220KΩ
330KΩ
470KΩ
680KΩ
1MΩ
Figure 5
Wiper Contact
LugPC Board
The following test is to be made with your meter to determine that the resistors are in their correct circuit
positions. The resistors used in your circuit are gold banded with a tolerance of +
5%. That means that a 10kΩ
resistor could measure between 9,500Ω and 10,500Ω and be correct. Each of the 24 resistance value positions
will be tested and recorded in the chart below.
Elenco®Electronics, Inc.
150 Carpenter Avenue
Wheeling, IL 60090
(847) 541-3800
Website: www.elenco.com
e-mail: elenco@elenco.com
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