Radio Shack SSM-1750 User Manual download pdf (Page 50)

RI5RI6

4

20060

RI7RI8

U2

r-

80

012

C6

11

90 0 013

SW2

30

70

R19

NRG

ow

02

03

Q4

R1

R2

R3

J1

R 4

C31

C7

R5

1

C4

100

2d

014

R

RI3

R6

CI

RI2

R14

U3

R7

DICE

Q5

C

2I

T

06

J2

RIO

.7.à9

071

08

RII

0

C5I

V

9

óSW1101II

I?

I14

I16 17

18

Fig. S.

Components

placement

/orientation

diagram

for

pc

board.

the board

by

installing

and soldering

into

place

the

diodes

at the

locations

indicated

by

numbers

only

along

the

bottom

of

the board

when

held in the

orientation

shown.

Make

sure

you

properly

orient

these

and

all

other

polarized

and

indexed

compo-

nents-

tantalum

capacitors,

LEDs,

transistors

and

ICs -before

solder-

ing

their

leads

or

pins

to the

board's

copper

pads.

After

installing

the

diodes,

pro-

ceed

with

the

resistors,

insulated

jumper

wires (in

the

locations

indica-

ted by

J1

and J2)

and

capacitors.

Next,

install

the

ICs.

You can

install

these

directly

on

the

board

or

via op-

tional

sockets

that

make

it easier

to

troubleshoot

the circuit

and

replace

a

defective

IC

if this should

become

necessary.

Use sockets

only

if the

plated- through

board

is used.

You

can

not use

sockets

with

a home-

made

board

because

they

do

not pro-

vide access

to solder

the pins

to the

required

pads

on

the

top

of

the

board.

Instead,

use

Molex

Solder

-

cons

that

do give

soldering

access.

Practice

safe

handling

procedures

for the

4520 CMOS

decade

counter

IC.

One

way to ensure

against

dam-

aging

this

IC with

static

electricity

is

to

make

sure

that

your

hand

is the

only

thing

that

touches

it once

it

is re-

moved

from

its protective

carrier

and

that you

hold the

board

in your

other

hand as you

plug

it into

the

holes

in the

board,

the

socket

or

the

Molex

Soldercons.

Install the

transistors,

making

sure

their

emitter,

base

and

collector

leads plug

into the

appropriate

holes

and

that

they

stand

approximately

'A

" above

the

surface

of the

board.

Install

the

2N2907

transistors

in the

Q2 and

Q7

locations

and

the

2N2222

transistors

in all

other

locations.

Note that

the

tabs

pointing

to

the

transistors'

emitters

point

upward

and

slightly

to the

left

for QI

through

Q4

and

downward

and

slightly

to the

right

for

Q5 through

Q8 as shown

in

Fig. 5.

Now

install

the

LEDs

in the

loca-

tions

indicated

by

numbers

only

in

the

upper

-left and

upper-

right.

Make

sure

that

the cathode

leads plug

into

the

holes

indicated

by the

flats

in the

case

outlines.

Let the

LEDs

stand

a

uniform

3/

" above

the surface

of

the

board.

You

might

want to

slip

3A

"

lengths

of

small

-diameter

plastic

tubing

over

each

anode

lead

before

plugging

the

LEDs

into

the

board.

The

tubing

serves

two

purposes

-

one

is to give

a uniform

height,

the

other

to provide

insulation

to pre-

vent the

LED

leads

from

shorting

to

each

other.

Bear in

mind that

light- emitting

diodes

are

heat sensitive

and

are easi-

ly damaged

by excessive

soldering

heat.

Therefore,

it is a good

idea to

use small

heat sinks

or

the jaws

of

longnose pliers

to

absorb

the

heat as

you solder

each

lead to

its copper

pad

on the

board.

When all

LEDs

have

been soldered

into

place,

arrange

them

in

symmetrical

patterns.

Solder

the

leads of the

battery

clip

to

the

labeled

9V

pads on

the

right

side

of the

board.

The red

clip

lead

goes

to the

hole

labeled

with the

+

sign,

the

black

lead to

the

hole

la-

beled

with the

sign.

Prepare

two

2"

lengths

of

hookup

wire

by stripping

'A

"

of

insulation

from

both

ends.

If you

use stranded

wire,

tightly

twist

together

all

fine

strands

of

wire at

each

end

and

spar-

ingly

tin

with solder.

Solder

one

end

of

each

wire to the

pads

labeled

SWI.

Then

install

slide

switch

SW2

direct-

ly on

the

board.

Cut two

sheets

of

% " -thick

Plexi-

glass to

6 "

x 5

3/

". Drill

four

% "

holes

through

both

sheets

for mount-

ing

the circuit

-board

assembly

cen-

tered

in the

area.

Drill

a

fifth

hole

for

pushbutton

switch

SWI

in the

top

panel.

Place

a 'h

"

x

3/

" strip

of

double

-sided

foam

tape

exactly

in

the

center

of

the

bottom

panel

for

mounting

the

9 -volt

battery.

Mount SWI

in

its hole

in the

top

panel.

Solder

the

free ends

of

the two

hookup

wires to

the

lugs

of SWI.

Then

use

1 " spacers

and

4 -40

x

3/

"

machine

hardware

to sandwich

to-

gether

the

circuit

board

and

Plexi-

glass panels.

When

you

are

finished,

there

should

be

eight

spacers,

two

at

each

corner,

separating

the

circuit

board

from

each

Plexiglass

panel.

Press the

battery

into

the

foam

tape

and

clip

the

connector

onto

its

terminals.

Reach

under

the

top

Plex-

iglass

panel

and

flip SW2

to

on.

The

LEDs

should

immediately

begin

flashing

and

eventually

stop

at a

roll

56

/ MODERN

ELECTRONICS

/ September

1986

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