LG OS-9020G Service Manual

OSCILLOSCOPE

OS-9020G

SERVICE MANUAL

LG Precision Co., Ltd.

Servicing Precautions

Please read all instructions in the service manual throughly before servicing. Disconnect power cord from power source before opening the enclosure.

Instructions

To maintain the precision and reliability of the product use it

in the standard setting (temperature 10

-35 o centigrade, humidity

45%-85%)

After turning on power, please allow a

15-minute

pre-heating period

before use. Triple-line power cord is to be used for the product. But when you

3. are using the doubleline cord,

make sure to connect the earth terminal

of the product to the earth at the power source for safety. For quality improvement the exterior design and specifications of the

4. product can be changed without prior notice.

Warranty

Warranty service covers a period of one year from the date of original purchase.

In case of technical failure within a year, repair service will be provided by our service We charge for repairs after the When the failure is a result of

accident, we charge for repairs

center

or sales outlet free of charge.

one year warranty period expires. user's neglect,

natural disaster or

regardless of the warranty period.

Notice

This Serivce Manual describes the most typical product of this model.

If there are any specific differences between this Manual and the servicing unit, please contact

Goldstar

Precision sales office in

your area.

Precision

Co-,

IdtcA

CONTENTS

GENERAL..

SPECIFICATIONS

ACCESSORIES

PREVENTIVE

CIRCUIT

CALIBRATION.. 6-l. Calibration Interval 6-2.

Test Equipment Required..

6-3.

Preliminary Procedure..

6-4.

Preliminary Control Settings

............................................

......................................

MAINTENANCE

DESCRIPTION..

................................

................

....................

....................................

.....................................

................................

..................................

.............................

14 14 14 14 15

10,

11,

12,

13*

6-5.

Initial Starting Procedure..

SEMICONDUCTOR LEAD

CONFIGURATIONS.................................

ELECTRICAL PARTS ARRANGEMENT

<WITH ADJUSTMENT LOCATIONS) . . . . .

ELECTRICAL PARTS LIST . . . . . . . . . . . . . . . . . . . .

BLOCK

WIRING

SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . .

MECHANICALPARTZ-LiST&EXPLODED

VIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

.............................

14,

EXTERNAL VIEWS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

GENERAL

This product of OS-9020G is as shown on Fig.1 and to generate triangular wave, sine wave and rectangular wave which have the frequency range and DC offset function from

frequency range from DC to

0.1Hz

1Hk

as well as the waveform meter that has

20Mk

and is a multipurpose portable oscilloscope

mounted by a function producer that generates otherwise pills of total

level of the same frequency as above.

Fig. l. OS-9020G Oscilloscope

OS-Q020G

SPECIFICATIONS

PARTS

CRT

Configration and

useful screen

Accelerating

potential

Phosphor

Focussing

Trace rotation

Intensity control

Vertical Deflection

Band-width

(-3dB)

DC coupled AC coupled

Modes

SPECIFICATIONS

@inch rectangular screen with internal graticule

(

1 div = 1 Cm )

marking for measurement of rise time.

;

8x10 Div

2mm subdivisions along the central axis.

+1.9

approx.

KVDC (ref. cathode)

P31 (standard)

possible provided provided

CHl,CH2,ADD,DUAL (

DC to DC to

10Hz to 10Hz to

CHOP

ALT

20MHz

normal

7MHZ

magnified (x5)

20MHz

normal

7MHz

magnified (x5)

;

Time/div switch - 0.2s to 5mS.

Time/div switch - 2mS to

;

(xl)

0.2~s )

Deflection Factor

Accuracy

4) Input impedance

Maximum input

6) voltage

Input coupling

7) Rise time

Clil

10) *

out

Polarity invertior

Horizontal

Deflection

1) Display modes

2) Time base A

SmV/div

continuously variable between steps at least

(x5 MAG

;

5V/div

in 10 calibrated steps of a l-2-5 sequence

lmV/div to

normal

approx.

Direct ;250V(DC+peak

with probe

refer to probe specification

;

lV/div

;

f3%

lM-ohm

in parallel with 25pF

1:2.5

in 10 calibrated steps.)

magnified ;

f5%

AC),

DC - GND - AC

17.5nS

20mV/div

less(50nS

or less: at x5 MAG)

into 50 ohms ; DC to

10MHz (

-3dB )

CH2 only

xl , xl0

0.2us -

0.2Wdiv

in 19 calibrated steps, l-2-5 sequence.

uncalibrated continuous control between steps at least

(

X-Y

1:2.5

3) Hold-off time

variable with the

holdoff

control

PARTS

SPECIFICATIONS

Sweep

magnification

Accuracy

Trigger System

1) Modes

2) Source

3) Coupling

4) Slope

5) Sensitivity and Frequency range

AUTO,NORM

TV-VW-H

10 times (maximum sweep rate ;

Note

f3%, f5%

;

50nS/div,20nS/div

(0°C to

50C),additional

auto , norm , TV-V , TV-H

CH1 , CH2 , LINE , EXT

20Hz - 2MHz

INT EXT 0.2 vp-p

at least 1 div or

TIME BASE

+ or

0.5 div

20nS/div)

are uncalibrated.

error for magnifier f2%

2MHz - 20MHz

1.5 div

0.8

VP-p

l.OVp-p

6) External trigger input impedance

Max. input voltage

X-Y Operation

1) X-axis

2) Y-axis

3) X-Y phase deff.

Calibrator

(px.obe

Function Generator

adj)

1) Frequency Range

2) Output Waveform

approx.

lM-ohm

in parallel with 25pF

250V ( DC + AC peak )

(same as CH1 except for the following)

;

Deflection factor

;

Accuracy

f5%

Frequency response;

same as that of CH1

DC to

same as CH2

or less ( at DC to

approx.

1KHz

frequency ,

0.5V (*3%)

duty ratio : 50%

0.1 Hz to 1 MHz ( 7 range ) sine ,triangle , square

500KHz

( -3dH )

50KHz

square wave

)

3) Frequency stability

f0.5% (1/10/100/1K/10K/100K fl%

(1M

4) Frequency variable 10 : 1 Min.

5) Output impedance

50a

f10%

range)

range)[ after 15 minutes late power on

(

TrL

output; FAN-OUT 20 ea )

PARTS

Output Voltage

Sinewave

distortio

-n & jittering

SPECIFICATIONS

14Vp-p

Min. (open circuit) DC OFFSET provided (open circuit

TTL

LEVEL (square wave only)

2% Max.

less than

(10Hz -

l/33

100KHz) / lOHz(l00Hz

continuous variable

f6V

;

3Vp-p

Min.

range 0.1)

Min.)

Duty ratio

9) Square wave rise & fall time

Power Supply

Voltage range

2) Frequency

3) Power consumption

Physical

Characteristics

1) Weight

50f3% Max. ( at

50a

output

'ITL

output ; 25nS Max.

120nS

;

voltage range

100 ( 90 -110V) / 120 (108 -132V) / AC

220 (198

230 (207

1KHz

;

max. output level)

Max. ( at max.

output LEVEL into

- 242V) /

250V) /

50 / 60Hz

approx. 45W

7.4Kg

50n)

fuse

2A250V

lA250V lA250V

2) Dimension

Environmental

Characteristics

Temperature range

for rated operation

2) Max. ambient operating temp.

Max. storage

temerature

Humidity range for

rated operation

Max.ambient

operating humidity

320 mm

+10"Cto

C to

(WI

+35"C

-20" C to

140 mm (H) x 430 mm

(+50"Fto

+40 O

C (

+70 o

+32"F

C ( -4" F to

45% to 85% RH

35% to 85% RH

+95"F

+104'

+158

(L)

)

ACCESSORIES

(1) Cable (BNC to CLIP) (2) Probe (Option)

(3) Fuse ( 2A f (4) Power supply code (5) Operation manual

-___--__---_--_------~~~~~--~~--~~----~--~~--~--~--

100V

-------________--------~~~-~--~--__-_---------~~

-_--_----_-__-_-___--~-~------~~~~~-~-~~~~~

-__-_________-_--v---W-----------------------

1 2

120V

set or 1A for

220V

and

230Vset

)

_----

1 1

------

PREVENTIVEMAINTENANCE

Preventive maintenance,

when performed on a regular basis, can prevent

instrument breakdown and may improve the reliability of the oscilloscope.

The severity of environment to which this instrument is subjected will

determine the frequency of maintenance.

A convenient time to perform

preventive maintenance is preceding recalibration of the instrument.

Disassembly

Remove the top cover and the bottom cover of the instrument. Most of the internal parts of the instrument are now accessible, if access to the front of the circuit board are necessary, remove the knobs from the external control shafts on the board.

Cleaning

The instrument should be cleaned as often as operating conditions

require.

Accumulation of dirt in the instrument can cause component breakdown. The covers provide protection against dust in the interior of the

instrument. Loose dust accumulated on these covers can be removed with a soft cloth or small brush. Dirt that remains can be removed with a soft cloth dampened in a mild detergent and water solution.

abrasive cleaners should not be used. Cleaning the interior should only be occasionally necessary. The best way to clean the interior is to blow off the dust with a dry, velocity stream of air.

A soft-bristle brush or a cottontipped

low-

applicator is useful for cleaning in narrow spaces or for cleaning more delicate components.

Visual Inspection

The instrument should be inspected occasionally for such defects as

bracken

boards, and heat-damaged parts.

visible defects is apparent

if heat-damaged components are found. other trouble in the instrument the overheating is important to prevent

connections,

improperly seated transistors, damaged circuit

the corrective procedure for most

;

however,

particular care must be taken

Overheating usually indicates

;

therefore, correcting the cause of

recurrance

of the damage.

CIRCUITDESCRIPTION

The block diagram ( page 51 1 shows the overall relationship between all of the circuits. Complete schematics of each circuit are also given in

section

schmatics

diagrams ( page 52 to 68

Refer to these diagrams throughout the following circuit description for electrical values and relationship.

ATTENUATOR

Signals applied to the input connector can be either AC coupled or they can be disconnected to the internal circuit when S201

or DC coupled,

(

S301 1

GND position. Attenuation is determined by the setting of the VOLT The attenuator that is controlled by the VOLT

s10, s2, -5,

are between S202 ( S302 1 and S203 ( S303

3100 circuit.

-10

CH1

(CH21

circuits are in RA201 ( RA301 > and

INPUT

AMPLIFIER

Signal from the input attenuator is connected to source follower

( Q301 1.

follower, the signals will be

Q201 ( Q301 1.

is feed back to OP AMP through

Q204 (

When excessively high-amplitude signals are applied to the source

When

Q202 ( Q302 )

S202D ( S302D >

R23Q (

is open (

R328 ) amplfies the output signal of

and the gate-source junction of

PULLX5MAG 1,

Q304 > by 5 times.

DIV switch.

DIV switch has

+10,

-100 circuits

the signal that

+1/2, +l,

QZ01

And the signal of Q206 ( Q306 ) base is converted from a single-ended signal to a paraphrase signal by differential amplifier.

CH1 (CH2 1

PRFJWP&TRIGGERPICKOFF

Vertical preamp circuits provide control of vertical position. They also contain a stage to provide a sample of the input signal to the

trigger preamp circuit for internal triggering from the CH1 or CH2 signal only. And the trigger preamp of CH1 provides the CH1 input signal to the horizontal amplifier in the X-Y position of the TIME

DIV switch.

The trigger preamp circuit amplifies the internal trigger signal to the

level necessary to drive the trigger generator circuit.

VERTICAL CONTROL

The

vetical

switching circuit determines the input signal or combination of input signals to be connected to the vertical main amp. Input signal combinations that can be displayed are selected by D FLIP-FLOP that is controlled by the vertical mode switches and the X-Y position of the TIME / DIV switch.

In the DUAL modes, both channels are alternately displayed on a

shared time basis.

VERTICAL MAIN AMPLIFIER

The vertical main amplifier circuit provides the final amplification for

the vertical deflection signal before

it is applied to the vertical

deflection plates of the CRT.

TRIGGER GENERATOR

The Trigger Generator circuit produces trigger pulses to start the sweep generator circuit. The Trigger Generator circuit consists of the trigger source, trigger mode switch, TV

synchronization

circuit, trigger amplifier, U603 and etc. The Trigger Source Switch selects one signal of the signals from the vertical trigger preamps, power line source applied to this instrument, external trigger input BNC connector connected to front panel. The Trigger Generator Circuit has the circuit to control the trigger level and slope. The signal type is AC. The Trigger mode Switch determines the operating mode for the trigger generator

circuit. In the NORM mode, the sweep signal is generated only the trigger signal is generated,

Operation in the AUTO, TV-V mode is the same operation

as NORM mode, except that a free running trace is displayed when a trigger pulse is not present or the amplitude of the trigger signal is not adequate. The Base Signal of Q605 which enters through three switches,

etc.,

Tht>

is amplified by

amplified signal,

Q604,

the collector signal of Q604, enters the NO.2 pin of

Q605.

Q601, Q602

and

U603, outputs in NO.8 pin of U603.

The NO.8 pin signal of U603 is called trigger signal or trigger pulse.

Sweep generator circuit consists of sweep gate circuit and miller integrator. The sweep gate is on, a very little negative going signal is generated in the gate of The signal in the gate of amplified signal appears in the Emitter of enters the Base of This sweep signal is generated on commend

generator circuit.

The sweep gate circuit produces an unblanking gate to unblank the CRT during

sweep time.

HORIZONTAL OUTPUT AMPLIFIER

The Horizontal Output Amplifier provides the final signal amplification to drive the CRT horizontal deflection plates. The Horizontal Output Amplifier consists of six cascade stage amplifiers. The first stage horizontal main amplifier has a low input impedance and requires very little voltage change at the input to produce the desired output change. The output signal from complementary amplifier Q638, Q639 drives the right

horizontal

The

output signal from complementary amplifier Q636, horizontal deflection plate. The Horizontal Output Amplifier has the horizontal magnification and the horizontal position functions.

In all position of the TIME

.of

the horizontal output amplifier is the sawtooth signal from the sweep generator. In the X-Y position of the TIME signal of the Horizontal Output Amplfier is the signal from the channel 1 preamp circuit of the vertical deflection system.

Q612,

input Miller Integrator, by R-C network.

defbctim

Q612

is amplified by Miller Integrator, the

Q627

through R732.

plate.

DIV select switch except X-Y the input signal

(9614,

is called sweep signal and

(

trigger pulse ) from the trigger

Q637

drives the left

DIV select switch the input

The low voltage Power Supply Circuit provides five regulated sources ( -12

Volts,

source ( 195 Volts, system, horizontal deflection system

CRT CIRCUIT

Volts,

-I- 12

Volts, +55 Volts,

+28Volts )

used

+140

Volts ) and two unregulated to operate the vertical deflection and CRT driving circuit.

The CRT Circuit provides the voltage The circuitry consists of the z-axis high voltage regulator, high voltage

The Probe adj.

circuit produces a square wave output signal with accurate

levels and control circuits to operate CRT. amplifier, high voltage oscillator, rectifier and the CRT controls.

amplitude and frequency.

This output signal available as a square wave Voltage at the

( 1KHz )

connector.

0.5Vp-p

FUNCTION GENERATOR CIRCUIT

The basic waveform generated in the function generator circuit is the triangle wave. This is accomplished by charging and then discharging a capacitor by equal magnitude currents.

A dual comparator and flip flop

(C16,

C17, C18,

C20,

C21,

C27)

is being charged or discharged.

(U4, SN75107A)

determine whether the capacitor

when the voltage on the capacitor reaches the positive limit, the charging

current is switched off and the capacitor discharges until the lower limit is

reched

at which time the charging current is then reapplied.

the output of the dual comparator is a square wave.

To produce a sine wave,

the triangle wave is shaped by a special amplifier.

(Q8, Q9, Q10, Ql3)

Range switching is accomplished by changing the magnitude of the current

sources Dial frequency tuning

Wl, U2, Ql, Q3, Q6)

(VR8)

and the timing capacitor.

is done by charging the magnitude of the current sources. A frequency change of over a 10:1 is possible with the frequency Dial.

CALIBRATION

Goldstar

Precision provides complete instrument repair and calibration at our oversea's office and authorized dealer. Contact your local

Goldstar

Precision office or representative.

6-1. Calibration interval

To maintain instrument accuracy, perform the calibration of the OS-9020G Units at least every 1000 hours of operations or every six month if used

frequently.

6-2. Test equipment required

The following test equipment

(

Table 6-l > and accessories, or equivalent,

are required for the complete calibration of the OS-9020G Units.

The given specifications for the test equipment are the minimum necessary

for accurate calibration.

Therefore, the specifications of any test equipment used must meet or

exceed the list specifications. All the test equipment is assumed to be correctly calibrated and operating within the listed specification.

Operating instructions for the test equipment are not given in this procedure. Refer to the instruction manual for the test equipment if more information is needed.

6-3. Preliminary procedure

This instrument should be calibrated at an ambient temperature of

(

5°C 1

for best overall accuracy.

1. Connect the instrument to AC line voltage,

50/60Hz

line source.

+20'tc:

2. Set the instrument controls as given in the Preliminary Control Setting. Allow at least fifteen minutes of warmup before proceeding.

3. See the Adjustment Locations in the pullout pages.

6-4. Preliminary control settings

Preset the instrument controls to the settings given below, when starting the calibration procedures.

Controls

FOCUS

TRACE ROTATION1 As desired

SCALE ILLUM

V-POSITION

V-VARIABLE

INPUT

COUPLING

VOLTS/DIV

I@ V-MODE

CH2 INVERT

VERTICAL

HORIZONTAL

Settings

Midrange

Fully counterclockwise

Midrange

CAL(fully

GND (AC-GND-DC)

CH1 Normal (Pushed In)

clockwise

V/DIV

pushed in)

,,,

TRIG

LEVEL

SLOPE

MODE

HOLDOFF

TRIG SOURCE

FUNCTION GENERATOR

AMPLITUDE full counterclockwise

RANGE SW.

FREQ.

DIAL 0.1

Midrange, normal

+ Normal Auto

Fully counterclockwise CH1

H-POSITION

6-5.

Initial starting procedure

Push the POWER switch.

Wait a few seconds for the cathode ray tube A trace should appear on the display of the CRT.

If the trace disappears,

setting until the trace is easily observed.

Adjust FOCUS control for the best focused display.

Readjust POSITION controls if necessary, to

Midrange

OFFSET PUSH

(

CRT ) to warm up.

increase ( clockwise ) the INTENSITY control

center

the trace.

POWERSUPPLYSYSTEM

NOTE :

Before you begin,

see ADJUSTMENT LOCATIONS in the pullout pages.

Control settings

Preset the controls as given in the Preliminary Control Settings.

Cl1

Check Low-voltage Supply, if necessary.

a. Connect the digital voltmeter

+11.75V

+12.25V (+12V

(

DVM > from the +12 volt line.

point of horizontal board)

b. Connect the DVM from the -12 volt line.

-11.75v

c. Connect the DVM from the

: +

4.75V

to +

-12.25V (-12V

5.25V (+ 5V

point of horizontal board)

volt line.

point of horizontal board)

d. Connect the DVM from the +55 volt line.

+54 V to +58 V

e. Connect the DVM from the

+135 v to +143 v

f. Connect the DVM from the

+190

v to

[23

Adjust Low-voltage Supply.

Adjust the

+210

VR901

for DVM reading of -12V ( f

(+55V

point of horizontal board)

+140

volt line.

(+140V

point of horizontal board)

+195

volt line.

(+195V

point of horizontal board)

0.lV >.

C31

Check High-voltage Supply.

Connnect

the DVM to the H.V test point ( CRT SOCKET B/D

-K(20M) )

by High-voltage Probe. Check for DVM reading as -1805V - -1995V

Adjust the VR618 for DVM reading of -1900V (

;

(Horizontal B/D p/n

513-547 used only)

20V ).

DISPLAY

Control Setting

Preset the controls as given in the Preliminary Control Setting.

141

Check/Ad

Set the

TIMWDIV

a. Rotate the

just

CRT Bias.

switch to the

INTHNSITY

to the direction of 10 o'clock as shown.

1mS

INTEN

b. Observe the trace of CRT. c. Adjust the CRT Bias Adjustment VR617 so that the trace makes

an appear.

151

Check/Adjust Trace Rotation.

a. Check that the trace is parallel to the horizontal

center

line.

b. Adjust the TRACE ROTATION for a trace that is parallel with the

horizontal graticule lines.

[61

Check/Adjust

a. Vertical Mode switch to the CH2

switch to the

ASTIGmatism

[X-Y1

and FOCUS

position, and AC-GND-DC to GND.

[X-Y1

position, and Display

b. Set the INTENSITY control for a small spot, as the following

figure,

using position controls.

The

SDot

screen

c. Check that the spot is round.

d. Adjust the FOCUS adjustment and ASTIG adjustment VR616 for

a round spot.

HORIZONTALSYSTEM

Control settings

Preset the controls as given in the Preliminary Control Settings.

[71

Check/Ad

a. Set the input AC-GND-DC to DC. b. Set the c. Check that the time marks align with the graticule line over the

d. Adjust the H GAIN adjustment

C83

Check/Adjust Horizontal X 10

a. Set the

b. Set X 10

c. Check that the one-cycle time marks align with the ten division d. Adjust the MAG GAIN adjustment VR612 so that the one-cycle e. Push in the VARIABLE control after check and adjustment.

[91

Check/Adjust MAG CENT.

a. Set the TIME/DIV switch to the 1 b. Being the VARIABLE control is in pulled out state

c. Observe the movement of the left end of the trace. d. Adjust the MAG CENT adjustment VR614 for the movement of the

just Horizontal Gain.

TIME/DIV

center eight with the center eight graticule lines.

TIME/DIV

MAG ( Pull out the VARIABLE control

graticule lines, within 5%.

time marks align with the ten division graticule lines.

the left end of the trace is brought to the center point and then the VARIABLE is depressed.

end of the trace within f

switch to the lms.

DIVisions,

switch to the

within 3%.

VB611

MAG

Gain.

1mS.

0.2DIV.

so that the time marks align

mS.

(

Xl0 MAG

Cl01

Check/Adjust low spaced sweep accuracy.

a. Set the time mark generator for 5mS time marks. b. Set the c. Check that the time marks align with the graticule line over the

middle eigth divisions, whth 3%.

d. Adjust the

with the middle eight graticule lines.

Cl11

Check/Adjust High speed sweep accuracy.

a. Set the input coupling switch to DC.

b. Set the time mark generator for 10~s time marks.

c. Set the

d. Check that the time marks align with the graticule lines over

the middle eigh divisions.

e. Adjust VC601 that the time marks coincide with middle eight

graticule lines.

TIME/DIV

switch to 5mS.

5mWDIV

adjustment VR606 so that the time marks coincide

switch to the

10~s.

VERTIACALSYSTEM

Control settings

Preset the controls as given in the Preliminary Control Settings.

Cl41

Check/Adjust DC Balance

(

Step attenuator balance

a. Set the

VOLTWDIV

switch to the 5mV position.

b. Position the trace to the horizontal center line.

c. Change the PULL

x5MAG

switch to the

1mV

position.

d. Check that the trace is within 0.1 division of the horizontal

center line.

e. Adjust the CH1 ( CH2 > DC BAL

(

CH2 1, for a trace at the horizontal center line.

f. Repeat part

(a>

through

is noted when changing the

Cl51

Check/Ad

just ADD BALANCE.

Set the TIME/DIV switch to the

(e)

until less than 0.05 division shift

adjustment,VRZBl (

VOLTWDIV

setting.

1mS

position.

CH1 > or VR301

Set the CH1 and CH2 AC-GND-DC switches to GND.

Set the V-MODE switch to

[CHlI.

Next, Adjust the vertical Position control that the trace is

identical with the horizontal center graticule line.

Set the V-MODE switch to

Next, Adjust the vertical Position control that the trace is

CCH21.

identical with the horizontal center graticule line. Set the V-MODE switch to [ADD]. Check that the trace is identical with the horizontal center graticule line within f 0.5 division.

Adjust the ADD BALANCE adjustment VR501 for two times of the difference with the horizontal center graticule line.

[161

Check/Adjust Vertical Position Center.

a. Confirm the vertical POSITION control at the midrange. b. Check that the trace is within 1 division. c. Adjust the Position Center adjustment VR203

(

CH2 > for a trace at the horizontal center line.

(

CH1 >, VR303

Cl71

Check/Adjust

Xl AC

GAIN.

Set the TIME/DIV switch to the

Set the VOLTWDIV switch to the

1mS

position.

10mV

position.

Set the AC-GND-DC switch to DC.

Connect the square-wave

Adjust the output amplitude of that generator for 5 division

generator(

using

1KHz

output range ).

deflection of screen.

Check that the high-voltage level of pulse is flat.

g. Adjust the X 1 AC GAIN adjustment

VR202(

CH1

),VR302(

CH2 )

for a flat level.

Cl81

Check/Adjust Vertical Gain.

a. Set the VOLTWDIV switch to the

10mV

position and AC-GND-DC

switch to DC.

b. Connect the standard amplitude calibrator to the input Connector.

c. Set the standard amplitude calibrator for a

50mVp-p

signal. d. Check for a display of five divisions. e. Adjust the GAIN adjustment VR204 ( CH1

VR304 ( CH2 ) for a

display of 5 divisions within 3%.

f. Check all the VOLTWDIV switch settings.

Cl91

Check/Adjust Input Capacity (

a. Set the VOLTWDIV switch to the

ATT

10mV

position. b. Set the AC-GND-DC switch to DC. c. Connect the L-C meter to the input terminals. d. Check the input capacity for approximately 25pF.

C203

Check/Adjust Vertical Step Response.

Set the VOLTWDIV switch to the

E :

Set the

Connect the fast-rise, positive output

TIME/DIV

switch to the 0.2~s position.

square-wave generator to the input. Use a

10mV

position.

( 50mV, 1MHz )

500

termination

and cable.

Set the square-wave generator to

1MHz.

Adjust the square-wave

generator output for a 5 divisions display.

Adjust the VC503 for a square-wave that is flat.

CH1

Then, adjust VC501 for over-shoot that is

CH2: Adjust the VC306 for over-shoot that is

of the

+0.15DIV.

[Zl]

Check/Adjust Attenuation Compensation (

a. Set the AC-GND-DC switch to DC. b. Connect the square-wave generator to the CH1

terminals, check for a square-wave that is flat under the following settings.

ATI' G-0, Sl00 1.

(

CH2 ) input

(

flat top

)

ATT

t100

c. Adjust the trimmer condenser for a square-wave

(

flat top 1 under the following settings.

ATT

Sl00

II221

Check/Adjust Input Capacity.

a. Connect the L-C meter to the input connector. b. Check the input capacity for a approximately 25pF. c. Adjust the trimmer condensers for a 25

the following settings.

VOLTWDIV

0.1 v 0.5 V

VOLTWDIV

0.1 v

1 v

The square-wave generator output

5 v

The square-wave Adjust generator output

I 1

0.5 V 5 v

input capacity under

CH1 VC204 ( VC304 VC203

(CH21

(

VC303

ATT

Sl +10 t100

VOLTWDIV

)

1 v

0. 1 v

Adjust CH1 ( CH2

(

I I

]

VC201 ( VC301 VC202 ( VC302

VC305

> )

)

TRIGGERINGSYSTEM

C231

Check/Adjust TRIG CENT.

a. Set the TRIG SOURCE switch to the

the

VOLTWDIV

b. Connect the sine-wave generator to the input connector for a

(

50KHz

). c. Set the TRIG LEVEL knob to the midposition. d. Adjust the VR605 so that synchronization is effected on the

waveform,

e. Next, set the TRIG SLOPE to -(pulled out state) and insure

that synchronization is effected. After confirmation, leave the TRIG-SLOPE in the depressed state. Readjust when stepped out.

C241

X-Y

[24-l]

Operation

Check/Adjust X Gain.

a. Set the

[X-Y], the AC-GND-DC switch of CH1 to DC, the AC-GND-DC switch

of CH2 to GND.

b. Set the

c. Connect the standard amplitude calibrator to the CH1 input connector. d. Set the standard amplitude calibrator for a 50mV. e. Check for a display of

f. Adjust the X GAIN adjustment

within 5%.

switch to

0.3DIV

on the screen.

V-MODE

VOLTWDIV

10mV

and the

switch to

switch to the

CH&

divisions.

CHl,

the TRIG SLOPE knob pushed in,

TIME/DIV

the

TIME/DIV

10mV,

with Xl GAIN.

VR610

for a display of 5 divisions

switch to the

20~s.

0.3DIV

C24-21

Check/Adjust X Position Center.

a. Set the TIME/DIV switch to the

the horizontal POSITION control to the midposition and the AC-GND-DC switch to GND.

b. Check to see that round spot is near the center graticule and

is within 0.2 division against the horizontal line.

c. Adjust the X CENT adjustment

graticule center.

PROBE ADJUST

[251

Check/Adjust Probe Adjust terminal (

a. Connect the Probe Adjust terminal to the Digital Frequency Counter. b. Check for the Probe Adjust frequency of

c. Next, connect the Probe Adjust terminal to the oscilloscope. d. Check for the Probe Adjust output of e. Adjust the

0.495 to

0.5V

adjustment

0.505V.

[X-Y],

VR609

VRll01

for the Probe Adjust output of

the V-MODE switch to CH2

to position spot at the

O.SVp-p, 1KHz

lKHz,

0.5V,

within 20%.

within 3%.

FUNCTION GENERATOR SYSTEM

C261

CHECK/ADJUST

SYMMETRY

a. Setting of equipment for adjustment

FUNCTION GENERATOR

FUNCTION RANGE

FREQ.

DIAL

AMPLITUDE

SINE (

( 1 10 ( 1 100

PUSH

0.1 ( >

FULLY CCW

( * )

)

(MINI

OFFSET

OUTPUT

PULL (

TTL(

FULLY ccw (

* OSCILLOSCOPE

VOLTS/DIV

TIME/DIV

COUPLING

b. Connect output terminal of F/G

uS/DIV

DC ( *

mV/DIV

( *

(

(50Qcz)

with BNC to BNC cable.

SQUARE

( >

(

)

0.2

GND(

mS/DIV

( 1

(

FULLYCW (MAX)

TRIANGLE(* >

(*>

l0K ( 1

1.0

FULLYCW (

500

V/DIV

lQQK ( > 1M (

(* 1

(*>

mS/DIV

AC(

(

and input terminal of oscilloscope

c. To adjust

VR2

(symmetry) of F/G so that on the oscilloscope screen as adjusting screen by a cycle of triangular wave as oscilloscope

100... I

._.. ,.._ ____

--++++-

.___--._..

. . . . . . . . . . . .

--4-++4--

---++++

K------a

Adjust the length of a 81 b

may

be equal (in the time axis).

may show as the following figure as to be full of the oscilloscope turning knob of SWP var of the

-____

------A

+ 53 hidden pages

LG OS-9020G Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual