Eico ST 40 Instruction Manual 2

Page 1

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CONSTRUCTION

The ElCO kit you are about to assemble and wire

has been designed to meet the highest standards of

performance. It is ahigh quality amplifierto be con-

structed from the finest components available any-
where.

The following Construction Book has been writ-
ten to carefully guide you through the construction of
your kit. if you follcwall the instructions implicitly,
and work carefullywlthout haste, you will be rewarded
with many years of fine performance from thisamplifier
and a personal inner satisfaction froma iobwell done.

YourConstruction Book: Beginning with the number on
this page, and throughout the rest ofyourConstruction
Manual, the page numbers are followed bya "C" (iC,
2C, etc. ). The instruction Manual, detailing the in-
stallation, operation and maintenance of your ampli-
fier, are identified by numerals only, without any
letters Following these numerals.

Observe that the instruction Manual section pre-
cedes this page and follows the last page of your Con-
struction Book section. After you are certainthat you
have successfully completedthe wiring of your kit,
you no longer need the Construction Book. You may
remove these centrally located Construction pages,
leaving the instruction section intact for tutu-re refer-
ence. Keep the instruction Monualforinformation as
to the installation and operation, as well as for any
maintenance that may be necessary in the future, on
your amplifier.

Choosing a Workbench and Tools; Toavoid the acci-
dental loss or misp acemmt of components, choose a
convenientworkbench before unpacking your new kit.
You will find it mostadvantageous to choose a comer
on a table that willnot be used for any other purpose
until you have completed the construction ofyourklt.
Proper precautions should be observed to prevent dam-
age to any table top from a soldering iron or anyheavy
tools.

When you check the component parts against the
Parts List later on, it will be convenient to separate
the various pieces into types of components and hard-
ware sizes. itwili be convenient to keep these sorted
pieces separated in the compartments of special ly made

trays. Small cartons, egg trays or a refrigerator ice.

tray with dividers serve equally well.
Several basic tools are required to constructing
this kit. They'are:

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BOOK

l. Screwdriver :- 3/16" to V4" blade

2. Screwdriver - 1/8" blade

3.. Longnose pliers - 5" or 6"

4. Diagonal wire cutters

5. Soldering iron (100 watts), solder gun or
pencil iron (35 watts).

6. Gas Pliers

7. High quality rosin core radio solder. DO
NOT use Acid Core solder or Paste fluxes under any
circumstances.

Thevfollowing tools are useful, but are not abso-
lutely necessary to construct this kit:

1. Socket wrench set

2. Open and wrench set

3. Wire stripper
Unpacking the kit: This procedure serves two purposes.
Firstiipermits you to become acquainted with the vari-
ous types of components. Secondly, itenables you to
ascertain ifyou receivedall the parts required to build
the kit. This is your opportunity to have any packing
errors corrected. '

When unpacking, handle allparts carefully so that
you will not damage any fragile components. Do not
throw any packing material away until after having
checked all components" Check each part off against
the Parts List" which you will find in yourlnstruction
Book. Check the packing for any small PQTTSo

From time to time, due to modernization or possible
error, corrections may be necessary to your Parts List.
it there areany changes to be made, they will be listed
on the loose addenda sheets included with this book.
Make the corrections if any, before checking your
components. if no corrections of your Parts List are
noted on the addenda sheets,lor therevare no addenda
sheets, assume your Parts List is correct, and commence
to check all components against this list.

To enable rapidldentificotion ofelectronlc parts,
each part has been assigned one or two letters of the
alphabet calleda "reference designation". These "re-
ference designations" are nothing more than an initial
letter or two representing the name of the part. For
example, a vacuum tube has been assigned the refer-
ence designation letter V, anda transformer the letter
T. Thus, if you have eleven vacuum tubes and three
transformers in yourklt, these parts would be identified
by the designationVi through Vii and Ti through T3,
respectively.

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PAGE 2C

The reference designation assigned to receptacles
(often referred to as lacks) isthe letter J. The differ-
ent types of jacks and plugs used in this kit are so
lettered and illustrated here as well as in the construc-
tion steps. In some cases, three iacks are mounted on
one bakelite strip and are so noted.

AC
RECEPTACLE

in some cases, these iacks are insulated from the
Chassis. A bakelite insulator used between the chassis
and the iack is supplied for this purpose.

The reference designation assigned to capacitors
is C.

Some capacitors, suchaselectrolytics, are marked
plus (+) and minus (a). These are the only capacitors
that must be mounted in a specific direction. Follow
the direction for mounting described in the appropriate
steps below. When no direction is mentioned, mount
the capacitor either way. Some molded paper capac-
itors have a black line near one end. Although these
can be mounted without any concern for direction, it
is preferable that you followthe direction for the black
line shown onthe drawing. if there is no black line on
the drawing or on the capacitor, iust mount the capac-
itor in either direction.

The peak or working voltages are important cap-
acitor characteristics. A capacitor marked witha high-
er voltage maybe substituted for a lowervoltage unit.
Thus, a 1000 volt capacitor may be used in place of a
500 volt unit. The reverse is obviously not true. You
cannot use a 500volt unit as a substitute for a i000 volt
capacitor. Where more than one capacitor of identical
value but different breakdown voltages are used, the
unityou are to use is indicated in the appropriate con-
struction step.

Ceramic capacitor tolerance may be noted by a
letter rather thananumber. "K" is iO%. "M" is 20%,
"P or "GMV" means guaranteed minimum value.

Ceramic capacitors have specific temperature char-
acteristics -- percent and degree of variation of cap-

acity with temperature. These variations are indicated
by means ofa code numberstamped on most capacitors.
Thus, a capacitor marked 68 25E indicates a 68mmf
capacitor having a 25E temperature characteristic.
The actual meaning onSE, or any other characteristic,
is important to the engineer. When building the kit,
be sure to use the capacitor with the characteristic
specified by the engineer, if it is indicated in the
construction steps. if no value is indicated in the
construction book, use any of the ceramic capacitors
of propervalue, tolerance and voltage characteristics,
supplied with the kit.

Resistors are denoted by the symbol letter R.

Some resistors have their resistance value stamped
on the surface of the resistor body. However, other
fixed resistors are coded with color bands which indi-
cate their value. The actual color code of these re-
sistors isnoted in the parts list. in some instances, even
when the color code is noted, in the book, the actual
resistor value may be stamped on the body, rather than
the color code.

The tolerance ofa resistoristhe amount the resist-
ance can vary around Its marked value. Thus, if a
iKQ (i000 ohms) resistor has a :i:i0% tolerance, its
actual value can be between 900(2th and i100 ohms.
if the same resistor has a i5% tolerance, its actual
value can be between 950 ohms and i050 ohms. The
fourth color band from the end of the resistor, indi-
cates the tolerance, The gold band indicates a 5%
tolerance, the silver band 0: l0% tolerance and the
absence ofa band a 20% tolerance. This tolerance
value isalways stotedor given as part of the color code
when the resistor is listed. if the resistor is marked with
a number rather than a color code, the tolerance, is
stamped on the body. in your kit, 5% resistors may be
substituted for l0% and i0% resistors substituted for
20%. However, be certain that you do not use at io%
resistor when a 5% resistor is required or a 20% resistor
when a 10% or 5% resistor is specified.

Resistors are capable of dissipating power. Large
resistors handle more power while smaller ones handle
less. A i/Z watt resistor is usuallysmalierthana iwatt
unit, while a iwatt resistor is usually smaller than a 2
watt unit. if like valued resistors are used in the kit,
differing in power, rating, the proper resistor to use is
designated in the particular construction step.

Besides the fixed resistors discussed, there are also
variable resistors known as potentiometerss They may
be equipped with shafts on which a control knob may
be mounted. The potentiometer combinations R3l-R32
and R33-R34, are both dual pots controlled by one
shaft. R45-R46 and R57-R48 are dual pots each con~