Epson L90P - TM Two-color Thermal Line Printer Manual de usuario descargar pdf (Pagina 66)

°

o

1±2

source

of 3.6

volts ( the

same

voltage

used

for the

IC circuit).

The

lamp should

glow and

be plainly

visible at

the

top

of

the probe.

Touch the

probe

tip

to the

3.6 -volt

source

and

note that

the

lamp

goes off.

If the

lamp either

doesn't

light

or doesn't

go

off when

it

is supposed

to,

remove the

circuit

from the

probe

and

check

for accidental

shorts

that

may

have occurred

during

assembly.

Test Set.

There

are

two

circuit

boards

in

the

test set:

an

oscillator

and

a

sock-

et- contact

board.

The

oscillator

section,

whose

schematic

is

shown

in

Fig. 3,

is

assembled

on the

PC board

with

the

foil

pattern

shown

in

Fig.

4. Mount

the

components

on

the

board

as

shown

in

Fig.

5.

To

test this

circuit,

connect

the

board

to

ground

and

+3.6

volts

at

the

indi-

cated

places

and

connect

an

oscilloscope

across

the

OUT terminals.

Depending

on

the position

of

Si, you

should

see

either

a

2 -Hz

or

10

-Hz

pulse train.

Make

the

socket-

contact

board

using

the

foil pattern

shown

in

Fig. 6.

Solder

the

12 spring-

contact

terminals

and

the

two

IC

sockets

in place

as

shown

in Fig.

7.

Looking

at

the top

(non

-foil) side

of

the

socket

-contact

board,

orient

the

S-

pin

round socket

so

that pin

8 (

identified

by a

small

projection

on

the

socket)

is

in

the

position

shown

in Fig. 7.

Make

some sort

of

marks

on

the board

to

iden-

tify

pin 8

and to

identify

the

dot

and

72

O

O

-1

Fig. 6.

Actual

-size foil

pattern

for

the socket -con-

tact

board.

Switch

Si cutout

and

mounting

holes

are

dependent

on the particular

switch

you are

using.

3/32 OR

#

42

DRILL

#25

DRILL

(12)

(41

DRILL

AND

CUTOUT FOR

SWITCH

USED

14 13

12

10 9 8

DOT ON

IN -LINE

IC'S

FLAT

ON --¡

ROUND

IC'S

1111,f

I 2 3

5 6

7

#64

DRILL

(22)

SUPPORT

HOLES

Fig. 7.

Parts layout

for the

socket

-contact

board.

Note the three

support

holes

for

oscillator

board.

notch

end of

the

in -line

socket.

At the

same

time,

mark the

LOW and

HIGH

frequency

positions

for

switch

Si. The

hole

for this

switch

can

be

cut to

fit

the

switch

used.

The oscillator

board

is mounted

on the

socket

-contact

board

using

three pieces

of stiff

wire

about 1/2"

long.

Insert

the

three

wires

in the

indicated

holes

on

the smaller

board

(Fig.

5)

and solder

them

in place.

Insert the

other ends

of

these

wires

in the appropriate

holes

in

the

larger

board

and

solder

them

in place.

Clip

any

excess

wire

from

the top

of

the

board.

Connect

Si to

its

leads.

On

the

upper

surface

of

the

metal

chassis,

cut

out

a

rectangle

4" by

2" so

that the

larger

board

can

be

mounted

within

the

chassis

and

secured

with

ap-

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