Elenco Electronics ST-751 Assembly Instructions Manual

Signal Tracer Kit

MODEL ST-751

Elenco®Electronics, Inc.

Cop

yright © 2005, 1996 by Elenco

®

Electronics

, Inc. All rights reserved. 753031

Revised 2005 REV-E

No par

t of this book shall be reproduced b

y an

y means;

electronic, photocopying, or otherwise without written permission

from the publisher.

Assembly Instructions

Parts List

If you are a student, and any parts are missing or damaged, please see instructor or
bookstore. If you purchased this signal tracer 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.

Resistors

Qty. Symbol Description Part #

1 R6 100W 5% 1/4W (brown-black-brown-gold) 131000
1 R16 220W 5% 1/4W (red-red-brown-gold) 132200
1 R10 1kW 5% 1/4W (brown-black-red-gold) 141000
1 R13 2.7kW 5% 1/4W (red-violet-red-gold) 142700
1 R14 3.9kW 5% 1/4W (orange-white-red-gold) 143900
1 R8 4.7kW 5% 1/4W (yellow-violet-red-gold) 144700
1 R5 6.8kW 5% 1/4W (blue-gray-red-gold) 146800
3 R3, R9, R15 10kW 5% 1/4W (brown-black-orange-gold) 151000
1 R12 47kW 5% 1/4W (yellow-violet-orange-gold) 154700
2 R1, R2 100kW 5% 1/4W (brown-black-yellow-gold) 161000
1 R4 180kW 5% 1/4W (brown-gray-yellow-gold) 161800
1 R7 220kW 5% 1/4W (red-red-yellow-gold) 162200
1 R11 Trim Pot 220kW 191622

Capacitors

Qty. Symbol Description Part #

1 C1 .001mF Discap (102) 231035
3 C2, C3, C7 .1mF Discap (104) 251010
4 C4,C5,C6,C9 10

mF Electrolytic (Lytic) 271045

Semiconductors

Qty. Symbol Description Part #

1 D1 Diode 1N5234 315234
1 Q2 Transistor 2N3904 323904
1 Q1 Transistor MPS 5172 325172
1 U1 IC LM-358 330358
1 D2 LED Diode .125” 350001

Miscellaneous

Qty. Description Part #

1 PC Board 512751
1 Switch Slide DPDT 541023
1 Probe Tip 616001
1 Knob (white) 622019
1 Earphone Jack 622102
1 Case 623007
1 Earphone 8W 629350
2 Screw #4 x 5/8” 643450
1 IC Socket 8-pin 664008
1 Alligator Clip Black 680001
1 Alligator Clip Red 680002
1

Alligator Clip Green

680003
1 Label 720510
12” Wire 815820
36” Cable 3-wire 870801
2” Tubing #20 PVC 890020
48”

Solder

9ST4

-1-

Introduction

Assembly of your signal tracer will prove to be an exciting project and give
much satisfaction and personal achievement. If you have experience in
soldering and wiring techniques, you should have no problems. For the
beginner, care must be given to identifying the proper components and
good soldering habits. Above all, take your time and follow the easy step­by-step instructions. Remember, an ounce of prevention is worth a pound
of cure. Avoid making mistakes and no problems will occur.

Parts Verification

Before beginning the assembly process, familiarize yourself with the
components and this instruction book. Verify that all parts are present.
This is best done by checking off each item against the parts list.

Resistors are identified by their color code as shown in the assembly
instructions.

Soldering

The most important factor in assembling your signal tracer is good
soldering techniques. Using the proper soldering iron is of prime
importance. A small pencil type iron of 25-40 watts is recommended. The
tip of the iron should be the flipplet point type and at all times kept clean
and well tinned. Many areas on the main 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
of 60/40 alloy. Do not blob the solder over the lead because this could
result in a cold solder joint.

Assemble Components

In all of the following assembly steps, the components must be installed
on the top side of the 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. Clip excessive leads with diagonal cutters. Then, place a
check mark in the box next to the step indicating that the step is complete.

-2-

-3-

Step-by-Step Assembly Instructions

Refer to Figure 1, install and solder the following resistors.

R1 100kW 5% 1/4W brown-black-yellow-gold
R2 100kW 5% 1/4W brown-black-yellow-gold
R3 10kW 5% 1/4W brown-black-orange-gold
R4 180kW 5% 1/4W brown-gray-yellow-gold
R5 6.8kW 5% 1/4W blue-gray-red-gold
R6 100W 5% 1/4W brown-black-brown-gold
R7 220kW 5% 1/4W red-red-yellow-gold
R8 4.7kW 5% 1/4W yellow-violet-red-gold
R9 10kW 5% 1/4W brown-black-orange-gold
R10 1kW 5% 1/4W brown-black-red-gold
R12 47kW 5% 1/4W yellow-violet-orange-gold
R13 2.7kW 5% 1/4W red-violet-red-gold
R14 3.9kW 5% 1/4W orange-white-red-gold
R15 10kW 5% 1/4W brown-black-orange-gold
R16 220W 5% 1/4W red-red-brown-gold
R11 Trim Pot 220k

W

Figure 1 - Top Legend

Install and solder D1, the 1N5234 diode. Note: the diode has polarity
as indicated by the band. Mount the diode with the band corresponding
to the PC board marking as shown in Figure 2.

Install and solder the 8-pin IC soc

ket (U1). Carefully install the LM-385

IC (see Figure 3).

Be sure that the notch is in the correct direction as

sho

wn in Figure 1.

Trim Pot

Band

Figure 2 Figure 3

Notch