AEG Electrolux ERN 2922 User Manual download pdf (Page 31)

Fig. 4. Actual

-size etching- and -drilling guide

(A) and

wiring

diagram

(B) for

Digi -Ohm

pc

board.

board has

been designed to accom-

modate

either

vertical-

or

horizontal

-

mount

trimmers. Use only cermet or

wire

-wound trimmers, again to

en-

sure

temperature stability.

Next,

cut

the header

strip

into four

strips of eight and one strip

of

four

pins. From

the component side of

the main board, push

the

longer -pin

end of the

eight

-pin headers through

the board's holes

at

locations

ji, 13,

J4 and Js.

Seat the

headers

so that

their plastic separators sit solidly

against the surface

of the board.

Do

the same

with

the four -pin

strip

in

the J2 location.

Plug

the

header pins into

the mat-

ing header sockets

on the

DMS mod-

ule to assure proper header align-

ment.

Solder

each

pin

to its associat-

ed copper pad

on the Digi -Ohm

board. Take

care to avoid creating

solder bridges

between the pads

on

the bottom

of the board.

After

soldering

all

pins

to the Digi-

Ohm

board, unplug

the

DMS

mod-

ule and set it

aside. Then install

and

solder

into place

the

four

-contact

terminal

block at TB -I

on the

Digi-

Ohm board. Make

sure that

the

holes

in

the terminal

block face the edge

of

the

board, as shown in Fig.

5(A).

Turn

over

the board and mount

CRI in place, again making sure that

it is properly oriented before

solder-

ing its leads to the copper

pads. This

diode

must mount on the foil side of

the board and

must

be

in intimate

contact

with

the copper

pattern to

ensure proper

temperature

tracking

with

UI. Hold the diode

tight against

the copper

pattern as you solder

each

lead into place and

until the liquid

solder sets.

Install UI on the

foil

side

of the

board as follows. First position

it so

that its leads are as shown

in Fig.

5(B).

Then before soldering

it into

place,

bend

its leads so that the

flat

side of the device's case

is against the

foil

pattern near

CR1.

Hold the di-

ode tight against the board

while

sol-

dering its leads to the copper

pads

and until the

liquid solder

has

set.

Later, after calibration

has been per-

formed,

you

will

epoxy both CRI

and UI to the board

to ensure maxi-

mum

temperature

stability.

The

circuit board

has provisions

for

an on

-board + 5 -volt

regulator at

U2. If

you

do

not need this regulator,

install a jumper

wire

in the two out-

side

regulator holes to connect TB/

to header J4.

Loosely twist together two 3'/4-

inch lengths

of

No. 24 hookup

wire

and strip

% inch

of

insulation from

both ends of

both

wires.

Plug one

wire into

the

hole labeled J nearest

the edge of the board to the left of

CR3 and solder into place.

Plug

the

other end

of this

wire

into the hole la-

beled

J

at pin

4 of J2 and solder

into

place. If both

wires

have the same

color

insulation,

use an ohmmeter

or

continuity tester to

identify the other

end of this

wire.

Then plug the ends

of the other

wire

in

the twisted

pair

into

the remaining

holes labeled J

and

solder into place.

As you approach final assembly,

decide

how

you

are going

to use the

Digi- Ohm -as a single,

fixed

-range

device; as a DIP -switch selectable

multiple

-range

device; or as a re-

motely

selected

multiple

-range

de-

vice.

How

you

plan on using this

project determines how to proceed

with

final assembly.

If you

have

decided to

use Digi-

Ohm as a single,

fixed

-range device,

simply solder a jumper

wire

in the

Say You Saw It In Modern Electronics February

1988

/

MODERN ELECTRONICS

/

39

1 2 ... 26 27 28 29 30 31 32 33 34 35 36 ... 79 80

Comments to this Manuals

No comments