AEG Electrolux ERN 2922 User Manual download pdf (Page 33)

Table

2. DIP

Switch Positions

to Use for Different

Ranges

SW1

Range /

Position

99.9

ohms

999

ohms

9.99K

ohms

99.9K

ohms

999K

ohms

1

ON OFF OFF OFF OFF

2 OFF ON OFF OFF OFF

3 OFF OFF ON OFF OFF

4

OFF OFF OFF ON OFF

5 OFF OFF OFF OFF ON

6 ON ON OFF OFF OFF

7

OFF OFF

ON ON ON

8 OFF OFF OFF OFF OFF

SW2

Range /

Position

99.9

ohms

999

ohms

9.99K

ohms

99.9K

ohms

999K

ohms

1

ON

I

OFF

OFF OFF

OFF

2

OFF ON

OFF OFF

OFF

3 OFF

OFF ON

OFF OFF

4

OFF

OFF OFF ON

OFF

5 OFF

OFF OFF OFF

ON

6

OFF OFF

ON OFF

OFF

7

ON

OFF OFF ON

OFF

8 OFF

ON OFF

OFF

ON

the Digi -Ohm module

onto the

rear

of the DMS as shown

in Fig. 7.

Connect

test leads to TBI at TP

+

and TP - . Connect an appropriate

power source

to TP+ and GND and

turn on the power supply.

At this

point,

your DMS module should be

displaying "EEE," indicating an

overrange (infinite- resistance) con-

dition. Shorting

TP +

to

TP -

should

cause

the

displayed

reading to drop

to

"000,"

indicating a 0 -ohm (short -

circuit) condition.

If you

encounter

any problems at

this stage,

UI, CR/ or the headers

are the

probable cause.

There are two

ways

to calibrate the

Digi -Ohm module. The first is

to use

several precision resistors

of differ-

ent

values,

one per range. The

sec-

ond, more accurate, method is to use

a precision current meter.

If you

use precision

resistors

for

calibration, select

resistors

of

known

value

in

the

middle

of each

range

to

be calibrated. If possible, the resis-

tors should be 0.1- percent tolerance.

For the second method, the

current

Fig.

6.

Actual

-size etching -and-

drilling guide

(A) and

wiring

diaram

(B) for LED

boards.

meter used should

have a rated ac-

curacy

of 0.1

percent.

If

you

are

using the

DIP -switch

method of

range selection,

refer to

Table 2 and position

S/ and S2

for

the lowest

range

(99.9

ohms

full -

scale).

If you

are using the

remote

switch

panel, connect

the cables at

S/

and S2

and set the selector

switch to

the 100 -ohm

range.

When

using

the

fixed -range arrangement,

substitute

the appropriate

values

(see

Tables

1

and 2)

for

the

specific

fixed range

you have selected.

For calibration

with

precision

re-

sistors,

connect

a 50 -ohm test resis-

tor

between

TP +

and

TP -

and adjust

the setting of

R2

until the

DMS

dis-

plays "050." For calibration

with

a

current meter, set the

milliammeter

to a

range

that

will measure 10 mA.

Adjust the

setting

of R2 for a

reading

of

10.00 mA on the milliammeter.

Repeat

the

procedure

for

each

range,

using the proper

middle

-of-

the -range

resistor (first method)

or adjusting

for the current

indicated in Table 1.

The appropriate decimal

point and

panel

LED (12

or

KSI)

should

light as

each

range is

selected.

If you

encounter

any difficulties,

check to see if the proper

value

of

trimmer potentiometer has been in-

stalled for each range. If

no

current

is

present, check

U1, CR1 and the

range -selection arrangement.

Make

any

necessary repairs and then

repeat

the calibration

procedure.

After

calibrating

all

ranges,

apply

a small amount of fingernail enamel

to the trimmer screws to prevent

Say You Saw

It

In Modern

Electronics February

1988

/

MODERN ELECTRONICS

/ 43.

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