Hafler DH-200 Instruction Manual

THE

POWER

AMPLIFIER

DH-200

INSTRUCTIONS

for

ASSEMBLY

and OPERATION

929204

$3.00

THE

DAVID

HAFLER COMPANY

5910 Crescent Boulevard, Pennsauken,

New

Jersey 08109

Please

refer to this serial

number in all communications

regarding this equipment.

INTRODUCTION

The

Hafler

DH-200 is a two channel audio power amplifier

designed to the very

highest

performance standards. It is

available either as a kit, or fully assembled. Its 100

watt

per

channel power rating is sufficient for

driving

all

loudspeakers in home applications, and its design provides

extremely low distortion of

all

types. A combination of high

performance,

dependability and reliability, and moderate

price

is in the

Hafler

tradition of using the

latest

technology

to provide outstanding value.

Combining

the

latest

power

MOSFET

technology with

uniquely

simple

and

effective

circuit

topology reduces distor-

tion of all types, and at all power

levels,

over the

full

audio
frequency spectrum, to the vanishing point. In addition to its
pace-setting performance achievements, the conservative
mode of operation accomplishes a new high in long term
reliability

and exceptional resistance to abusive operating

conditions.

This

is one of the direct

benefits

of

MOSFET

utilization

in overcoming a serious limitation of conven-

tional

transistors — their tendency to self-destruct under
other than normal operating conditions. So rugged is the
DH-200

that it can deliver as much as ten amperes into a

short circuit!

The

speed — measured as the

slew

rate — of this design
delivers unmatched transient linearity, revealing the most
delicate shadings,

textures

and nuances of the music, surpass-

ing

the capabilities of the most revealing loudspeakers and
cartridges by a wide margin. Coupled with its unconditional
stability, and ability to deliver adequate power into any
loudspeaker load, the result is absolute freedom from listen-
ing

fatigue. The longer you listen to this phenomenal
amplifier,

the more certain you will be that you could not

have made a better choice.

Though

modest in

cost,

the DH-200

evidences

the very
finest electrical and mechanical design. It avoids costly frills
and

unnecessary gadgetry while

providing

quality sound and

reliability

based on top grade components conservatively

operated.

The

oversized power transformer

and

bridge rectifier; the

massive

heat

sinks; the conservative operating

levels

of the

MOSFET

output

devices

— all are evidence of the design
efforts to achieve exceptional reliability simultaneously with
state

of the art

sonics

and specifications. And this circuit is
convertible (with an internal accessory bridging circuit
board)

to a high power monophonic amplifier with

equivalent stability and specifications.

The

fully complementary, symmetrical push-pull circuit,

which

is direct coupled throughout

(except

at the input), in-

corporates all silicon

devices

in a format which is directly
related to the highly acclaimed DH-101 preamplifier. Its
unique self-protecting output

stage

prevents the thermal

runaway

which is a common threat to solid

state

amplifiers.

The

ruggedness and conservative operation of the output

stage

allows the DH-200 to avoid the need for special protec-

tive circuits which could compromise audio performance.

Basic

protective

systems

provide maximum security against

malfunction

damage to the amplifier or the speaker: the AC

line fuse, B+

fuses,

thermal breakers,

and

loudspeaker

fuses.

Nothing

hinders the essential purity of the audio signal.

Those who use

these

instructions to

assemble

the

DH-200

kit will

find

that the

left

and right audio modules

(printed

circuit and

heat

sink

assemblies)

are preassembled

and

pretested.

This

greatly simplifies the kit assembly so that
it can be done in only a few hours without special skills or
know-how. Because of the modular arrangement, it is possi-
ble to operate on one channel if the other requires service,
and

obviates the need to return the entire amplifier in

cases

where one channel is inoperative.

Accessories for special applications include the input

bridging

circuit board for monophonic use; a panel for stan-

dard

19"

rack

mounting; and an alternative power

transformer

for international AC line

voltages.

Through

advanced engineering geared to the audio per-

fectionist, and an efficient no-frills approach,

Hafler

is mak-

ing

high technology high fidelity affordable.

CONTENTS

Operation

Page

3 AC

Line

Connections

for

Overseas

Use 12

Assembly

Instructions

4 Kit

Parts

List

13

Wiring

the Kit 6

Schematic

Diagram

14

If

Problems

Arise

10

Component

Value

Listing

15

Service

and

Warranty

11

Pictorial

Diagram

Insert

©

Copyright

1980.

All

rights

reserved.

2

INSTALLATION

The

DH-200 is most likely to be ihstalled out of sight in
most applications, since its power may be controlled by the
AC

switching of most audio preamplifiers, like the

Hafler

DH-101.

If your control unit

does

not provide switching

capacity sufficient for the amplifier's 5 amp

needs

(plus other

equipment it is

also

switching), you should use the amplifier's

own power switch. In that

case,

turn

on the preamplifier first;

then

turn

the amplifier on a few

seconds

after

the preamp has
been turned on, to avoid any unnecessary turn-on transients
from

some

preamplifiers. Likewise, switch the power

amplifier

off first.

If

the amplifier is to be installed

close

to a record player,

you

should first check its position for freedom from hum

pickup

by the cartridge from the field radiated by the power

transformer

of the DH-200. Although the design of the

transformer

minimizes such radiation, certain cartridges are

more

sensitive

than others, and require separation from the

amplifier.

Check

at a comparatively high volume setting, and

while swinging the

tone

arm throughout its arc. Often a few

inches additional spacing will eliminate the problem.

Be

sure to provide sufficient

ventilation

for the amplifier.

Unobstructed

air

circulation

around the finned

heat

sinks

and

above

the amplifier is important for long, trouble-free
life. Never put anything on top of the cover perforations. It is
normal

for the top and the

heat

sinks to become warm in use.

It is expected that the amplifier will always be resting on

its

feet,

which should be on a

hard

enough surface that air
flow underneath is not obstructed. If it is mounted in a rack,
or

through a panel, the

feet

may be removed so long as ade-

quate ventilation is provided through the bottom openings.

OPERATION

The

red pilot lamp which is integral with the power

switch

glows

whenever the amplifier is turned on. A blown

AC

line

fuse

is the most likely

cause

if it is not illuminated

when the amplifier is switched on.

The

yellow

lens

is a high temperature indicator. While it
is not likely that you will ever see it lighted, if it is, the
amplifier

will not produce sound. It indicates that one of the

thermal

breakers has shut down the amplifier

because

of ex-

cessive

temperature rise in a

heat

sink.

When

the

heat

has dis-
sipated in a few minutes, the amplifier should return to nor-
mal

operation. If the lamp again lights, check for insufficient

ventilation, or an

excessive

input signal, or an input which
may have dangerous signal content (such as oscillation).
Failing

evidence of this, the amplifier may have malfunc-

tioned. Because of the very large

heat

sinks, it is highly

unlikely

that any normal signal will

cause

the amplifier to

overheat.

Loudspeaker

Fuse Selection

The

DH-200 power amplifier is supplied with 2 amp

fuses

in the speaker lines. Experience has shown that since an

overload

must

exist

for a few

seconds

for a

fuse

to blow, a 2

amp

fuse

will protect most speaker

systems,

and only blow

when overload occurs. Smaller

fuses

tend to blow too easily,

and

larger

fuses

do not adequately protect most speaker

systems.

A

pair

of 5 amp

fuses

are

also

supplied as alternatives for

the speaker

fuse

holders. These should be substituted if the

power output of the amplifier is to be

tested,

or if the

amplifier

is to be operated at very high power

levels

into 4

ohm

loads.

If

the manufacturer of your speakers recommends a

specific value of

fuse

for their protection, we

suggest

that you

obtain 3AG

fuses

of that value and substitute them for the

ones

supplied.

Loudspeaker

Power Ratings

There

are no U.S. standards for rating the power han-

dling

capabilities of loudspeakers. As a result the manufac-

turers'

usual "music power" ratings, or

suggested

amplifier

limits,

are of only

minimal

help in determining

safe

operating

levels

with amplifiers which can deliver substantial amounts

of

power. You must take into consideration the type of

music, and the

levels

you like, to provide long term trouble-

free operation of

your

speaker choice, when you have a

size-

able amplifier like the DH-200.

Connections

AC

The AC

power cord should be plugged into 120 volts, 60

Hz,

on the switched output of a preamplifier which can

pro-

vide at

least

5 amps, or 600

watts.

Then

the amplifier power

switch may be

left

on, and it will be controlled by the rest of

the system.

Or,

it may be plugged into a 120 volt wall outlet,

and

switched on and off independently.

If

your line voltage is different, be sure you have the

alternate power transformer which can accommodate several

line

voltages,

and be sure it is

wired

for

your

mains voltage as

described later in this manual

before

you

plug

in the

amplifier.

Input

Conventional

shielded cables, such as

those

supplied
with your preamplifier, provide the input signal to the
sockets

on the back panel of the DH-200. Be sure that the
outer shield connection is secure, to avoid hum. The length
of

these

cables (so as to permit remote location of the

amplifier,

if desired) is limited only by the output impedance

of

the preamplifier. If it is 1,000 ohms or

less,

as with the

DH-101,

for instance, cable

lengths

up to 100

feet

are per-

missible without

loss

of performance. Special low .maci-

3

tance cables enable

even

greater distance

between

preanip

and

amplifier. It is desirable to keep the

left

and right input

cables

close

together

throughout their length to minimize the

likelihood

of hum pickup.

Also,

you should avoid running

them parallel to

AC

cords —

these

should be crossed at right

angles.

Output

The

loudspeakers (or headphones) connect to the red

and

black terminals in the center of the back panel. These

binding

posts

provide several convenient alternative con-
necting methods. The screw cap may clamp the bared wire
end,

or a "spade lug" attached to it, but a better connection

will

be made by locating the hole

drilled

through the shaft of

the terminal when the cap is unscrewed. Insert the twisted

end of the bared wire so that the cap will clamp it in place.

Always

be sure that no strands of wire are unsecured, and

that the bared end is not too long to

risk

contacting other

ele-

ments. A soldered end or fitting is the

safest

solution.

These terminals

also

accept standard plug-in "banana pin

connectors," including the double

ones

with standard 3/4"

spacing, available from electronic supply

houses.

These are
the most convenient, especially if you may wish to in-
terchange speakers occasionally.

It is important to maintain correct phasing of the
speakers when making their connections. Some speaker ter-
minals are coded red and black, or + and —, etc. It is im-
portant that the

"sense"

of one speaker's connections match

the others. If one is reversed, you will

find

that the sonic im-
age has a "hole in the middle," and that it is deficient in bass.
Speaker wire always identifies one conductor to make this
easy.

There may be a molded ridge in one lead, or the color

of

the insulation on one wire is different, or the wire itself

may be color coded. If pin plugs are used, be sure they are

There

are three basic rules for

success

in electronic kit

building:

1. Read the instructions carefully, and follow them in
order.

2.

Make

secure solder connections which are bright and

smooth.

3.

Check

your work carefully after each

step.

The

DH-200 preamplifier is a versatile component with

sophisticated

circuitry

which has been made

remarkably

easy

to

build

by individuals with many years of experience in the
design and engineering of the finest performing audio kits,
and

in the preparation of their manuals.

Kit

building should be fun, and we are certain you will

find

this to be so. Assembly will be faster, easier, and more

enjoyable if

you

have

someone

help you by reading the

steps

aloud,

selecting the required parts, and

preparing

the

neces-

sary wire

lengths

in advance as you proceed. Fatigue in-

creases

the

risk

of

error,

so take a break rather than push to

early

completion. There are relatively few separate compo-

nents

in this design, to make it

easy

to pack everything away,

if

need be.

color

coded, or that you follow the indexing

mark

on one

side

of the double connectors.

Select

speaker wire of sufficient

size

to preserve the high

damping

factor (and

excellent

speaker control) of your

amplifier.

Standard 18

gauge

lamp cord ("zipcord") is

satisfactory for

distances

up to 30

feet

for an 8 ohm speaker.

As

the distance increases, larger wire

sizes

are recom-

mended. The

next

larger wire

size

is #16, and it is often

preferred

by perfectionists. If you have 4 ohm speakers, the

maximum

cable length for

best

results is halved.

The

black output terminals are electrically connected to

the

chassis

internally. Be certain that when the amplifier is

operated in its normal

stereo

mode that the red output ter-

minals are

never

connected together. In the special

case

when
the amplifier has been internally modified for monophonic
bridged

operation, the output is taken from the two red ter-

minals

only.

Then,

the black terminals are

left

unconnected.

Headphones are normally operated from the loudspeaker
outputs, but are usually connected through a junction box
which

provides switching from phones to speakers. Such a

box usually provides

some

added resistance to reduce the

sensitivity of the phones, and thus minimize the likelihood of

hearing

component noise,

because

of the low setting re-

quired

at the volume control. Some headphone

boxes

utilize

a "common

ground"

system

which makes it

particularly

im-
portant that you carefully observe the proper connections.
While

the black ground terminals

can

be connected together,

the red

ones

must not be.

Some headphones, such as electrostatic types, are

less

sensitive

and may need little or no resistance in

series

for

normal

operation. These could be easily interchanged with

the speakers through the use of double banana plugs.

Your

work area should have good lighting, the proper

toots,

and a place where the large pictorial diagram can be

tacked to the wall within

easy

reach for checking. The

tools

should include:

1. A 40 to 100

watt

soldering

iron

with a 1/4" or smaller

tip which reaches at

least

600°F.

2.

60/40

(60% tin)

ROSIN

CORE

solder, 1/16" diameter

or

smaller.

3. A damp

sponge

or cloth to wipe the hot tip of the

iron.

4. A wire stripping tool for removing insulation.

This

can

be a

single-edge

razor blade, but inexpensive stripping

tools

are safer, faster and easier.

5. A medium-blade screwdriver (about 1/4" wide).

6.

Needle-nose

pliers (a long, narrow tip).

7. Diagonal or side-cutting small pliers.

8.

Large

"gas" or "slip-joint" pliers.

9. A 1/4" "Spin-tite" nut driver may be helpful, but is not

necessary.

4

ASSEMBLY

INSTRUCTIONS

A

soldering "gun" is not recommended. The unfamiliar
user is more likely to damage the etched circuit boards with
its higher

heat

potential and unbalanced weight.

Also,

because

he may not wait long enough for it to reach operat-

ing

temperature each time it is switched on, poor solder con-
nections are more likely. Pencil irons are much lighter and
easier to use, and there is no waiting time when solder con-
nections follow in

sequence,

as in kit building.

Make

sure

you

have a holder for it, though, and always unplug it when

you

take a break.

Proper

Soldering

There

are four

steps

to making a good solder connection:

1.

Make

a good mechanical connection to hold the wire in

position while

heat

and solder is applied.

2. Heat

the junction

of the wire and iug, or

eyelet,

with the

bright,

shiny tip of the

iron.

3.

After

heating for a couple

seconds,

apply solder to the

junction.

It should melt immediately and flow smoothly

around

both surfaces.

4.

Allow

the connection to cool undisturbed.

Remember

that the connection is made by the solder, not

by

mechanically attaching the wire to the terminal. Usually
the wire is looped through the lug and crimped in place, but
some

prefer to just place it through the hole and rely on the

stiffness

of the wire to hold it while soldering. Eyelet connec-

tions, of course, are handled this way.

Good

solder connections are

essential

for trouble-free,

noise-free operation. A good solder joint

does

not require

much

solder

around

the conductors. Never

"butter"

partially

melted solder on

the

joint,

as it is

useless.

A good connection

looks smooth and bright

because

the solder

flows

into every

crevice when the parts are hot enough. The

iron

must have a

bright,

shiny tip to transfer

heat

easily to the

junction.

That's

why the damp

sponge

should be used frequently to wipe the

tip,

and occasionally you must add a small amount of solder

to the tip, too. If a connection is difficult to heat, "wet" the

tip with a small blob of solder to provide a bigger contact
surface to the joint. Once the solder

flows

around the con-

ductors,

any movement must be avoided for a few

seconds

to

allow a good

bond.

When

cool, check the connection by wig-

gling

the wire. If

ir.

doubt, or if the connection is not shiny,

re-heat the

joint.

Excess solder may be removed

from

a con-

nection by heating it and allowing the solder to flow onto the
iron,

which is then wiped on the sponge.

ALL

SOLDER

USED

MUST

BE

ROSIN

CORE.

Never

use acid core solder or any separate flux in

electronic work. Silver solder is

also

not suitable. If

in

doubt

about

unmarked

solder, always obtain a fresh supply of

rosin

core solder. We recommend

60/40

for

easiest

use. Do not

confuse it with

40/60,

which is harder to melt.

The

general procedure is to use a hot

iron

for a short time

to

heat

a connection, then add solder with the

iron

still in

contact. Remove the solder

once

it flows, and then remove

the

iron.

A cooler

iron

applied for a longer time is more

likely

to damage components, or lift the copper circuit pat-

tern

from

the boards. A break in the etched circuit can be
mended by simply soldering a small piece of wire across it.
Do

not allow much build-up of solder on the tip of the

iron,

or

it may

fall

into adjacent

circuitry.

When

soldering to an

eyelet

on the

board,

insert the wire

from

the components side, and apply the

iron

to the bottom,

leaving

some

bare wire exposed so that you can see that the

eyelet

is then filled with solder for a secure bond. A

round

wooden toothpick is

suggested

so that you can

heat

and clear

an

eyelet

of solder if it hinders your inserting the wire. Some

builders

prefer to clear every

eyelet

first with a touch of the

iron

and toothpick.

Others

connect the lead by

bringing

it up

to the center of the

eyelet

on top of the

board,

applying the

iron

from

the bottom of

the

board,

and

pushing the lead in as

the solder in the

eyelet

melts. If the wire has first been

"tin-

ned,"

usually no additional solder is necessary, but it is a

good practice to push the wire

through,

and then back it up a

bit,

to be sure solder fills the

eyelet

from

both

sides.

On the

bottom of the

board,

make certain a

bright,

shiny flow is evi-

dent

from

the wire, across the

eyelet,

onto the circuit pattern

on

the

board.

It is

essential

that the

eyelet

be fully soldered to

the

.circuitry,

too.

"Tinning"

refers to the process of

applying a light coating

of

solder to the bared wire end.

This

keeps

all the strands

secured, and

also

makes a good connection easier. Simply

touch the wire with the

iron

for a couple

seconds,

and apply

solder.

Allow

the

excess

to flow away onto the

iron.

When

properly

done, the wire is uniformly bright, and no larger

than

before. The hookup wire supplied with this kit

does

not

normally

need tinning, for it is pre-tinned.

5

Wiring

the Kit

Mechanical

Assembly

If

any components are unfamiliar to you, checking the

pictorial

diagram

should

quickly

identify them.

Or,

the

quan-
tities, and the process of elimination as you check the parts
list,

will

help. The pictorial diagram is necessarily distorted

to

some

extent

for

clarity,

so that you can trace every wire in

a

single overall view for verification as you work. You may

wish to check off

on

the

diagram

as you solder each location.

To

"prepare"

a wire means to cut the designated length

from

the coil of that color, and strip about 1/4" of insulation

from

each end. The wire supplied in the kit is #18, so you

can

set adjustable wire-strippers accordingly. The

transformer

leads are #16 or 18, and the line

cord

is #18.

Be

careful that you do not nick the wire when you strip it

(that

can

happen more easily

if

you

do not use wire strippers)

for

that

weakens

it. The wire supplied in this kit is "bonded

stranded,"

which provides exceptional flexibility with resis-

tance to breakage for easier use.

Whenever

a connection is to be soldered, the instructions

will

so

state,

or indicate by the symbol (S). If

more

than one

wire is to be soldered to the same point, they

will

be

indi-

cated by (S-2), (S-4), etc. If soldering is not called for, other

connections have yet to be made to that terminal.

They

would

be more difficult if the connection was already

soldered.

Every

connection in the kit

will

be soldered when

it is complete.

After

soldering a connection, it is

best

to clip

off

any

excess

lead length to minimize the possibility of a
short circuit (as on switch lugs, where terminals are very
close

together), and for

neatness.

Be

sure that uninsulated wires cannot touch adjacent ter-

minals or the

chassis

metalwork.

The

symbol (#) indicates a connection is to be made to

that point.

When

a lug number is specified without (#), it is

simply

a locating reference.

When

the instructions

call

for twisting two or three wires

together, the length of wire indicated anticipates a

fairly

tight,

uniform

twist

by

hand,

of three

full

turns every two in-

ches. If

you

find

the wires too short, loosening the

twist

will

gain

some

needed length.

Handle

the

circuit

boards

carefully.

They

represent a ma-

jor

part

of the kit

cost.

Stand-up

components, such as transis-
tors, should be checked when you install the module, to be
sure all leads are separated.

All

of

the

active

circuitry

is contained on the

PC-6

board,

which

has been carefully

tested

to assure that it

meets

every

specification.

Only

the interconnection of power supply

ele-

ments is left to the

builder.

Take

the time to be accurate and

neat, and you can be sure that your completed amplifier

will

meet

the performance of a factory assembled unit, and can

continue to

perform

properly

for years to come.

Check

your

work,

and make sure the entire

step

has been completed

before placing a check

mark

in the space

provided,

and con-

tinuing

on to the next

step.

KEP

nuts have been supplied as a convenience. These

have lockwashers attached, and the lockwasher always

goes

onto the screw first. If the

sheet

metal

screws

have hex heads,

you

may

find

it easier to first start them with a regular

screwdriver,

to set the thread, and then use the more con-

venient nut

driver,

if one is available.

1 •

When

you unpack your kit, you

will

find

that the

transformer,

large capacitors, and the output assem-

blies have been temporarily fastened to the

chassis

for

safe

shipment. Disengage

these,

and include this

hard-
ware with the rest when you check off the components
against the parts list in the back of the manual. We
recommend

this check-off to be sure you have every-

thing,

and to enable you to identify any unfamiliar
items by comparing them with the pictorial diagram.
An

egg

carton

is ideal for keeping

hardware

items sepa-

rated.

A

"set" of hardware includes one screw and one

KEP

nut
(with its attached lockwasher). Always install the lockwasher
side of the nut first. If the

size

of the hardware is not

specified, use the #6 size. The smallest

size

is #4 and #10

the largest. Always insert the screw

from

the outside of the

chassis.

It

will

simplify matters if

you

first separate the #4 nuts

from
the #6 nuts, which have the same outside dimensions. A #4
screw

will

pass

through a #6 nut, aiding identification.

2 • Select the four rubber

feet,

four

sets

of

hardware,

and
the chassis. Insert each screw through a foot so that the
head is recessed, and install the

feet

on the outside at

each corner hole.

3 • Select the two red output terminals. Install them in the

sequence

shown below, in the two center

holes

R2 and

R3

at the rear of the chassis. Before you fully tighten

the first nut, unscrew the cap to

expose

the hole

drilled

through

the threaded shaft. Connection of loudspeaker

wires

will

be easier if

these

holes

are positioned ver-

tically. A nail

through the hole

will

keep it positioned

while the hardware is tightened.

Each

connecting lug

should

point downward before the last nut is secured.

Be

sure both nuts on each terminal are tight, as they

are difficult to reach when the amplifier is completed.

4 • Select the two black output terminals and install them

on

either side of

the

red

ones,

at Bl and B4. Be sure the

shaft

holes

are vertical, the lugs point downward, and

each nut is tight.

5 • Select the two

round

fuse

holders, and two each 1/2"

rubber

washers, lockwashers and nuts.

First

install the

rubber

washer on the holder, so it

will

be outside the

chassis, and then fasten the

fuse

holders at

LF

and

RF,

with the tip lugs

pointing

away

from

each other, toward

the

edge

of the chassis.

6

6 • Select the larger

round

input socket, its insulating disc,
the solder lug with lockwasher teeth, two #4 screws,
and

the two nylon nuts.

This

socket

will

be installed at

RS.

The inside of

the

chassis

at

RS

and

LS

has not been

painted,

so that a good ground connection can be

made. It may be necessary to clean this with a solvent,

or

with an eraser, before the

sockets

are installed. Place
the solder lug on the lower mounting screw inside the
chassis, followed by the insulating disc, then the socket.
Position

the lug toward the

edge

of the chassis. The

shorter

ground

lug on the socket should also be nearest

this right

edge.

Secure this socket with the nylon nuts.

7 • Select the other input socket and two

sets

of #4

hard-

ware. Install it at

LS

after cleaning the unpainted area,

with its short ground lug near the left

edge

of the

chassis.

8 • Select the four-lug rectifier block RB, the long #6

screw, and a nut. Install the rectifier in the center hole
near the rear of the chassis, with the plus (+) terminal
located over the tiny indexing hole at position four.
Correct

orientation of this rectifier is essential for

proper

wiring.

9 • Select the single

fuse

clip,

and one set of #4 hardware.

Install the clip in the right front

chassis

hole

FC,

closest

to the foot.

10 • Select the two

dual

fuse

clips and four

sets

of #4

hard-

ware. Install

these

in the pairs of

holes

FL

and FR on

either side of the center of the chassis.

11 • Select the two-lug terminal strip and one set of #4

hardware.

Install it in the front hole TS, next to the

single

fuse

clip.

Note the position of the mounting lug

(to the right) in the pictorial diagram.

NOTE:

Kits

provided

with

the

multiple

voltage

power

transformer

for

locations

outside

;K-

United

States

which

use a

line

(mains)

voltage

other

than

120

VAC,

are

also

supplied

with a five-lug

ter-

minal

strip

which

is

to be

installed

in

place

of

the

two-lug

strip,

using

an

additional

set

of

#4

hardware

near

the

dual

fuse

clip.

12 • Select the power switch. If

it

says

"Carting,"

position it

with

lug

#3 at the top. If

it

says

"Chicago,"

position the

small

protruding

plastic lug at the bottom. Snap it fully

into the front

chassis

hole PS

from

the outside.

A

soldering

iron

will

be used

regularly

for installing the wir-

ing.

Be sure you wipe its tip frequently with a damp cloth or

sponge, as a bright tip

will

make connections easier with

less

likelihood

of overheating components. If it is difficult to heat

a

connection in a couple of seconds, apply a small

amount of

fresh

solder to the tip so it can flow around the connection

and

provide good heat transfer.

Take

the time to observe the direction each wire

takes

from

its connecting lug, so that when you connect the first end, it

will

be pointing in the right direction.

This

makes the job

neater, and assures that each wire is long enough.

13 • Prepare a

6-1/2"

green wire. Connect one end to

dual

fuse

clip

FL

lug #

1.

Connect the other end to the other

dual

clip FR lug #1. (S).

14 • Prepare a

6-1/2"

white wire. Connect one end to FR

lug

#3. Connect the other end to

FL

lug #3. (S).

15 • Select the 2.2 ohm (red-red-gold) resistor. Cut each

lead

to 112" or

less.

Connect one end to the separate

solder lug installed under input socket RS. (S).

Con-
nect the other end to the short (ground) lug #2 of
socket RS.

16 • Prepare a 10" green wire and a 10" white wire. Twist

these

together uniformly (about three complete

twists

every two inches). Connect the green wire to the short

RS

lug #2. (S-2). Connect the white wire to RS lug

#

1.

(S). Place

these

wires out of

the

way, over the

edge

of

the chassis.

17 • Select one of the

.0047

mfd

film

capacitors. Cut each

lead

to 1/2", and connect one lead to

fuse

holder RF

lug # 1.

Connect the other lead to RF lug #2.

18 •

Prepare

two 8" white wires.

Start

with

one wire project-

ing

3/4" beyond the other, and

twist

them uniformly
together throughout their length. Connect the project-
ing

end to RF lug #1. (S-2). Connect the correspond-

ing

end of

the

other wire to

RF

lug #2. (S-2). Place this

pair

over the

edge

of the chassis.

19 •

Prepare

an 11" white wire

and a 9"

green wire. Starting
with the white wire 3/4" longer than the green wire,
twist

them together to within one inch of the other end

of

the green wire. At the beginning end, connect the
green wire to output terminal lug #B4. Connect the
white wire to lug #R3. (S). Place

these

wires off to the

right.

20 • Prepare a 6" green wire. Connect one end to lug #B4.

(S-2).

21 • Prepare a 10" white wire and a 10" green wire. Twist

them together, and connect the green wire to the short
LS

lug #1. (S). Connect the white wire to LS lug #2.

(S). Place

these

wires to the left, over the

edge

of the

chassis.

22 • Select the remaining

.0047

mfd

film

capacitor, and cut

each lead to 112". Connect one lead to

LF

lug #

1,

and

the other lead to

LF

lug #2.

23 • Prepare two

7-1/2"

white wires. Start with one wire

3/4" longer, and

twist

them together throughout their

length. Connect the longer end to LF lug #2. (S-2).

Connect

the other wire to

LF

lug # 1.

(S-2). Place

these

wires off to the left.

24 • Prepare a

9-1/2"

white wire and a 10" green wire.

Starting

with the white wire 3/4" longer than the green

wire,

twist

them together to

within

one inch of

the

other

end

of the white wire. At the beginning end, connect

the green wire to output

terminal

lug

#B1.

Connect

the

white wire to lug #R2. (S). Place

these

wires off to the

left.

25 • Prepare a 6" green wire. Connect one end to lug #B1.

(S-2).

7