Epson L90P - TM Two-color Thermal Line Printer Manual do Utilizador descarregar pdf (Página 68)

When

testing an

IC out of the

circuit, plug

it into the proper socket,

make

the

connections

called

for in the test table, apply

power,

and

use

the probe to test

device

operation.

TEST TABLE

FOR IC'S*

OUT OF CIRCUIT

Function

Input

Output

Inverter

signal

blinks

Gate

all

gnd

off

any

one

signal,

others

to gnd

blinks

Flip

-flop

Reset

or Q O or

gnd

then

gnd

signal

gnd

blinks

off

blinks

off

on or off

off

For

Motorola

series

IC's.

"As

indicated

by probe lantp.

+Indicates

+3.6

volts.

MC-00P

a td

Fairchild

0L900

note

where the signal stops (if

the board

faulty). If

number of flip- flopsoare

involved

(as

countdown

circuit),

the probe lamp

will blink

more slowly

you

move

down the

chain. In

this case,

place Si

the

HIGH frequency

position

to speed up the counting.

You

can

trace

the

signal through

gates or inverters

observing the presence of signals

the

inputs

and output.

Out of Circuit Tests. To test

unmount-

(loose) IC's, remove

the

power from

the

test

fixture and insert the IC in its

socket, observing

the notch and dot code

on in -lines and the flat, tab, or color

dot on

round IC's.

The only direct connections to the

IC's

are +3.6 volts

to pin 11 of

the

in-

line and pin

8 of the

round socket

and

ground to

4 of both types. The rest

of the

contacts

to the

are made

through

the

12 spring clips.

Apply power

to the test

fixture

connecting

the

black

test lead to ground

and

the

red

test

lead to a source

+3.6

volts.

Test

the

IC using

the accompany-

ing table

as a guide.

Use

small

lengths

of insulated

wire

with bare

ends to make

any

necessary

interconnections.

The

two

-speed

oscillator

built

into the test

fixture

serves as

the

signal

source.

-o-

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