Elenco Electronics K-37 User guide

RESISTANCE SUBSTITUTION BOX
MODEL K-37
Copyright © 2004 byElenco®Electronics,Inc. All rights reserved. 753400
No partof this book shall be reproduced byanymeans; electronic,photocopying, or otherwise without written permission from the publisher.
Elenco®Electronics, Inc.
Assembly and Instruction Manual

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/e-
mail 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 #
1 R1 10W5% 1/2W brown-black-black-gold 121001
1 R2 22W5% 1/2W red-red-black-gold 122201
1 R3 47W5% 1/2W yellow-violet-black-gold 124701
1 R4 100W5% 1/2W brown-black-brown-gold 131001
1 R5 220W5% 1/2W red-red-brown-gold 132201
1 R6 330W5% 1/2W orange-orange-brown-gold 133301
1 R7 470W5% 1/2W yellow-violet-brown-gold 134701
1 R8 680W5% 1/2W blue-gray-brown-gold 136801
1 R9 1kW5% 1/2W brown-black-red-gold 141001
1 R10 2.2kW5% 1/2W red-red-red-gold 142201
1 R11 3.3kW5% 1/2W orange-orange-red-gold 143301
1 R12 4.7kW5% 1/2W yellow-violet-red-gold 144701
1 R13 6.8kW5% 1/2W blue-gray-red-gold 146801
1 R14 10kW5% 1/2W brown-black-orange-gold 151001
1 R15 22kW5% 1/2W red-red-orange-gold 152201
1 R16 33kW5% 1/2W orange-orange-orange-gold 153301
1 R17 47kW5% 1/2W yellow-violet-orange-gold 154701
1 R18 68kW5% 1/2W blue-gray-orange-gold 156801
1 R19 100kW5% 1/2W brown-black-yellow-gold 161001
1 R20 220kW5% 1/2W red-red-yellow-gold 162201
1 R21 330kW5% 1/2W orange-orange-yellow-gold 163301
1 R22 470kW5% 1/2W yellow-violet-yellow-gold 164701
1R23 680kW5% 1/2W blue-gray-yellow-gold 166801
1R24 1MW5% 1/2W brown-black-green-gold 171001
MISCELLANEOUS
Qty. Description Part #
1 PC Board 517007
1 Switch SPDT PC Mount 541103
2 Switch 12 Position 542013
2 Knob 622009
1Case with Cover 62RS400
4Screw 4 x 1/2” Phil A 642465
2 Nut 9mm 644102
2 Washer 9mm x 15mm 645103
1 Alligator Clip Black 680001
1 Alligator Clip Red 680002
1Wire BlackStranded 12” 814210
1Wire Red Stranded 12” 814215
1 Solder 9ST4
-1-
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 10Wto 1,000kW(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
12 Multiplier T
olerance
PC Board
BAND 1
1st Digit
Color Digit
Black0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9
BAND 2
2nd Digit
Color Digit
Black0
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-
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.
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!
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 flowonto the
lead as shown.
3. Allowthe 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
Agood solder connection should be bright, shiny,
smooth, and uniformly flowed over all surfaces.
Types of Poor Soldering Connections

-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 - 4.7kW5% 1/2W Resistor
(yellow-violet-red-gold)
R11 - 3.3kW5% 1/2W Resistor
(orange-orange-red-gold)
R10 - 2.2kW5% 1/2W Resistor
(red-red-red-gold)
R8 - 680W5% 1/2W Resistor
(blue-gray-brown-gold)
R7 - 470W5% 1/2W Resistor
(yellow-violet-brown-gold)
R9 - 1kW5% 1/2W Resistor
(brown-black-red-gold)
R1 - 10W5% 1/2W Resistor
(brown-black-black-gold)
R2 - 22W5% 1/2W Resistor
(red-red-black-gold)
R3 - 47W5% 1/2W Resistor
(yellow-violet-black-gold)
R5 - 220W5% 1/2W Resistor
(red-red-brown-gold)
R6 - 330W5% 1/2W Resistor
(orange-orange-brown-gold)
R4 - 100W5% 1/2W Resistor
(brown-black-brown-gold)
R19 - 100kW5% 1/2W Resistor
(brown-black-yellow-gold)
R20 - 220kW5% 1/2W Resistor
(red-red-yellow-gold)
R21 - 330kW5% 1/2W Resistor
(orange-orange-yellow-gold)
R23 - 680kW5% 1/2W Resistor
(blue-gray-yellow-gold)
R24 - 1MW5% 1/2W Resistor
(brown-black-green-gold)
R22 - 470kW5% 1/2W Resistor
(yellow-violet-yellow-gold)
R18 - 68kW5% 1/2W Resistor
(blue-gray-orange-gold)
R17 - 47kW5% 1/2W Resistor
(yellow-violet-orange-gold)
R16 - 33kW5% 1/2W Resistor
(orange-orange-orange-gold)
R14 - 10kW5% 1/2W Resistor
(brown-black-orange-gold)
R13 - 6.8kW5% 1/2W Resistor
(blue-gray-red-gold)
R15 - 22kW5% 1/2W Resistor
(red-red-orange-gold)

SW3 - PC Mount Switch
Mount SW3 in the place shown on the PC board.
Solder into place.
Red Test Lead
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.
SW1
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.
Jumper wire from SW1
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.
Installation of Knobs if an Ohm Meter is Available
Place the knobs loosely on the switch posts. Push
the slide switch to the “W” position. Connect an ohm
meter 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
“KW” 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
-5-
Figure 1
Bend T
abs
Over Wire

-6-
Installation of Knobs without an Ohm Meter
If an ohm meter 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 470W(R7) resistor, to be sure that the
switch is set in the proper position. Align the knob
on the SW1 (W)switch to the 470 position, push the
knob onto the shaft. Follow the same procedure for
switch SW2 (KW), except follow the copper run to
the 6.8KW(R13) resistor. Align the knob on the
SW2 (KW)switch to the 6.8 position.
TESTING THE CIRCUIT
SCHEMATIC DIAGRAM
SW1 WWPOSITION
Value Position Meter Reading
10W
22W
47W
100W
220W
330W
470W
680W
1000W
2200W
3300W
4700W
SW2 KWWPOSITION
Value Position Meter Reading
6.8KW
10KW
22KW
33KW
47KW
68KW
100KW
220KW
330KW
470KW
680KW
1MW
Figure 5
Wiper Contact
Lug PC 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 10kW
resistor could measure between 9,500Wand 10,500Wand 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
[phone]
Web site: www.elenco.com
e-mail: [e-mail]