Samsung SC-528DXL, SC-528L, SC-528DX Service Manual

Picture tube

SC-528DX. ANALOGUE. SC-528DXL. ANALOGUE. SC-528L. ANALOGUE.

Input signal

Display

Colors

Synchro-

nization

Resolution

Video band

width

Display area

AC Input

voltage

Power

consumption Dimension

Weight..,,..

SPECIFICATION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M36KUT26XXOl(F)

M36KUT23XXOl

15 Inches diagonal 90 degree deflection,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Video

. .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Any

....

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Horizontal

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

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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Horizontal

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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6OW(MAX.) i_

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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 640 dots(H) x 350 Lines

~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7fjMHz(_3&)

matrix

0.7Vp_p Analog level positive

Sync : TTL level

Colors

31,5/35.2/35.5/37.9/40,1/48,4/56.4KHz

Vertical : 56/60/70/72/87Hz

640 dots(H) x 400 Lines 640 dots(H) x 480 Lines 800 dots(H) x 600 Lines 1024 dots(H) x 768 Lines

260 +3mm

Vertical : 195

AC9OV_264V(47-63HJ

354(W)X364(H)

j4kg(Approx)

(SC-528DX)

(F) (SC-528DXL)

0.28mm

*3mm

10%

X4OO(D)mm

dot pitch, black

1. GNEERAL INFORMATION

(1) SAFETY PRECAUTION

WARNING : Service should not be attempted anyone untamilliar with the necessary precautions on this unit.

The following precautions are necessary during servicing.

1. Some parts such as a picture tube in this unit have special safety-relate charateistics for X-RAY RADIATION protection. For continued safeth, the parts replacement should be undertaken referring to item 2 below.

2. Many electrical mechanical parts in this unit have special safety-related characteristics for protectron against shock hazard and others. These characterstics are often passed unnoticed by a visual inspection and the protection afforded by them cannot necessarily be obtained by using replacement components rated for higher voltage wattage, etc. Replacement parts which have these special characteristics are identifide in the manual and supplements by shading on the schematic diagram and the parts list. Before replacing of these components read the parts list in this manual carefully

3. When replacing chassis in the cabinet, always be certain that all the protective devices are installed properly, such as insulating covers, strain relief, etc.

Before replacing the back cover of the set, thoroughly

spect

inside the cabinet to see that no stray parts or tools

in-

have been left inside.

5. Before returning the set to the customer always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as terminal, screwheads, metal overlays, control shafts, etc, To be sure the set in safe to operate without danger of electrical shock, Plug the AC

rectly into a

transformer during this check). Use an AC voltmenter having 5000 ohms per volt or more sensitivrty in the following manner.

Connecta 1500ohm, 10watt (PF),

ground (water pipe, conduit, etc.) and the exposed metallic

parts, one at a Measure the AC voltage across the combination of 1500 ohm resistor and plug at the AC outlet and repeat AC voltage measurements for each exposed metailic part.

Votage

sponds to tutes a potential shock hazard and must be corrected diately.

115V

AC aoulet (do not use a line isolation

resistor, paralleled by a

250VAC capacitor, between a known good earth

time.

O.l5mfd( /IF)

measured must not exceed

0.2mA

AC any value exceeding this limit

capacitor, Reverse the AC

0.3V

RMS. This corre-

lrne

cord

0.15mfd

constr-

imme-

diL

MONITOR

0.15~

Place this a water pipe, conduit etc.

proge

on each

Vdtrneter

Hook-up

250V AC

for leakage Current

(50000hm per volt or more

Reading should not exceed

Good earth Qroud such as

exposed metallic part

chebc

sensitivrty)

0.3V.

“-_

(4) User ADJUSTMENTS

Side

Power switch

Contrast

Brrghtness

Vertical Position Horizontal Position Height Width Side-Pincushion Degauss

Turn the display on and off with this switch. 0 : Turn off, Adjusts the white level of the image, It sets the contrast between the light and dark portions of the Image. Adjusts the black level of the image, It sets the overall brightness. Adjusts the vertical position of the image, The image should be centered on the screen. Adjusts the horizontal position of the image. The image Adjusts the vertical height of the image. The vertical image size should be approximately 195mm. Adjusts the horizontal width of the image. The horizontal image size should be approxjmately 260mm. Adjusts the left and right sides of the image. The irnage should be a rectangle. Removes the color impurities which can appear on the screen after longtime use. It is automatically activated when you turn on the

I :

Turn on

display.

shouki

be centered on the screen.

2. CHARACTERISTICS

[l]

GENERAL CHARACTERISTICS

CDT (Color Display Tube

CDT Phosphor

D.Y

3 4

7 8 9

[

2) Electrical Characteristics

Deflectron Angle Resolution Sync. Frequency Input Signal

AC Input Display Color

Drsplay

Display Character

Detiption

Zone

2-1. Input Power

Nominal Remark

)

M36KUT26XXOl

M36KUT23XXOl

P 2’2 Dark Phosphor 90”

80Ox600/1024x768Lines H

31.5/35.2/35.5/37.9/48.1/48.4/56.4KH/

V :

56/60/70/72/87Hz

R.G.B

Analog

9OV -

264V

Unlrmrted

H :

260mm,

Up To 2400 Characters

(F) :

SC528DX

(F) : SC-528DXL

v : 195mm

TOSHIBA

WITH ASN WITH VLF. Graphic Mode

Free Voltage

NO --

1 2 3

The

drsplay

device shall

Description Nominal Power Source Frequency Power Consumption MAX.

maintarn

the specified performances in the range described below.

9OV -

47-63Hz

8OWilO%

264V

Remark

Universal Power

2-2

Input signal

The input signals shall be applied to the display devices through a signal cable tor. (Rof. Fig 1 Timing chart)

Section

Desaiption Nominal

which

must be intemeded as part of the moni-

Remark

Video

Signal Red Green Blue Input impedance 75 Ohms

Horizontal Frequency 31.5/35.2/35.5/37.9/48.1/48.4/56.4UH~

-Sync.

Vertical

-Sync

Video input Polarity Positive Pixel Rate Rise/Fall Time Less than 8 nsec

Sync input Pulse Width

Front Porch

Back Porch

Sync Input

Pulse Width

Frecuency

Front Porch 0.014-1.2 Back Porch

0.0 to

0.7Vpr

Analog

Up to 75

2.4 6 Level 6 5V

1.2-3.92psec

0.18-1.12psec

1.25-4.6 p

2.4V ZZ

0.06-0.2msec 56/60/70/72/87H~

0.48-1.88

MHz

set

Level 6 5V

msec msec

2-3.

CRT Electrode voltage

Heater 2 3 4

Cathode( R.

Gride

Gride $3

Anode Voltage

G. B)

#I @

Description

6.3V i 0.5V,

80V f 20V ov- -70v 600V + 1

6.5kV

24kV

+0.5kV

I!I

OOV

kV@OuA

Nominal

300mA

30mA

RGf?X3rk

Screen

Focus

-__

2-4. Timing

Ct-wactristic

The monitor shall be capable of displaying 5 different vertical resolution within the scan frequencies as well as the scanning mode. (REF. FIG 1 TIMING CHART)

(3ilM;$tNICAL

The total weight shall be approximate 14kg.

Exter

Width

Height

Length

33. Tilt/Swivel

The inclination of the must be min. 180deg.

34. Tool Resin

TOd

Front

CHARACTERISTICS

nal Dimensions(n-rn)

Without Stand

354 335 400

suface

I I

Resin

KJU

of the screen shall be adjustable at least -5deg. With a

With Stand

354 364 400

I 1

PARCHMENT WHITE

color

min. ldeg

from the

wertrcal.

The swivel

I 1

Rear

Stand

KJU

PARCHMENT WHITE

1 1

3. SERVICE ADJUSTMENT

VOLTAGE ADJUSTMENT

Receive a cross-hatch pattern signal of 640 x 400 mode.

*Adjust contrast and brogtitness controls to maximum.

Adjust G2 control to minium. *Make sure the AC power supply voltage is at the specified value. *Adjust VRlOl(

HIGH VOLTAGE ADJUSTMENT

138.5V

line-ADJ. volume) for +b voltage equal to

138.5i-0.5V.

*Receive a cross-hatch pattern

*Adjust

VR102( +B controler)

stgnal

of 640 x 400 mode.

for the voltage of pin No.2 of FBT equal to 68f0.5V.

HORIZONTAL DEFLECTION CIRCUIT ADJUSTMENT

Horizontal

31.

*Disconnect the signal cable from signal source. *Adjust

*The horizontal frequency for other modes are automatically set by interface circuit.

Horizontal position adjustment. (H-SHIFT)

*Receive a cross-hatch pattern signal of 800 x *The picture is to be placed at the center position of the CDT screen by sdjusting

Horizontal

33.

*Adjust contrast and brightness controls to maximum. *Receive a cross-hatch pattern signal. (800 x 600 mode *Adjust

oscillation Frequency

VR302(horizontal

bottom side of front.

width adjustment. (H-WIDTH)

VR902(

H-WIDTH control) located at the bottom side of the front, for the H-SIZE equal to 260mm.

adjustment(H-HOLD)

frequency control) for the horizontal frequency equal to

600( 37.9kHz, 60HZ)

37.9kH, 60Hz)

mode.

4. VERTICAL DEFLECTION CIRCUIT

4-1.

Vertical oscillation frequecny adjustment.

*Disconnect the

Adjust VR305(VHOLD2) control to maximum value of resistance. *Adjust VR301 (V-HOLDl) for the vertical frequency equal to 48i0.5H,

Receive a cross-hatch pattern signal of 800 x

*Adjust VR903 located at the bottom side of the front for the V-SIZE equal to 195mm.

*Receive a cross-hatch pattern signal of 640 x

*Adjust VR305(VHOLD2) for the V-SIZE equal to 195mm.

4-2

Vertical linearity

*Receive a cross hatch pattern signal.

Adjust the size volume so that the height becomes 195mm.

*Adjust V-LIN volume( VR303) for optimum linearity.

4-3.

Vertical size adjustment

*Receive a cross hatch pattern

*Adjust

Vertical position adjustment (V-SHIFT)

*Receive a cross hatch pattern

*The picture is to be placed at the center position of the CDT screen by adjustiong

VR903(SIZE

bottom side of front.

signal

cable from signal source.

adjustmt(V-LIN)

control) located at the bottom of the front for the height of the pattern equal to 195mm.

(V-HOLDI, V-HOLD2)

600(37.9kHL, 60HL)

480(37.9kHZ 72H/)

(37.9kHz 60Hz

srgnal. (37.9kHz 60HL

signal.

(

37.9kHZ 60HZ

mode.

mode)

31.5i0.2kHL

VR904(H-SHIFT

VR905(

control) located at the

V-SHIFT control) located at the

5. VIDEO CIRCUIT ADJUSTMENT

1. Controls function

Brightness volume

This knob controls the black level of the image.

*R.

G. B gain volumes (VR401, VR402, VR403)

These volumes control the gain of RED, GREEN, BLUE video pre-amplifier.

R. G. B. bias volume

These volumes control the bias voltage of RED, GREEN, BLUE cathode of CDT.

Screen volume (On the FBT)

This volume controls the screen voltage of the CDT.

Cpmtrast Golume (VR907)

This knob controls the contrast of the image. It establishes the gain of the video amplifier but does not affect the raster

luminance.

Focus volume. (On the FBT

This volume controls the focus of the picture.

(VR906)

(VR405R, VR405G, VR405B)

)

6. WHITE BALANCE ADJUSTMENT

*Adjust R. G. 6. gain and bias volumes to mechanical center.

*Operate the set for 15 minutes to warm up.

Degauss the CDT face fully with degaussing tool.

*Adjust screen volume

*Adjust bias volume of R. G. B so that the color of the raster may becomes white.

*Now

adjust the screen volumes for the luminance of the raster equal to 1.0 F/L MAX. (without wideo signal)

*Receive a full white pattern signal. *Adjust R. G. B gain volume for the specified white color.

Use the color analyzer equipment.

Standard Color coordinate. (@lOF/L,

X = 0.281

Maximum brightness : More than 25

l With full white pattern. l Brightness V/R

Checking area : Center of display.

l Contrast V/R

kO.02,

fo’r

the luminance of the raster equal to l-3 F/L.

=0.311 kO.02

Set to raster cut off.

Set to maximum.

25F/L)

F/L.

7. FLASHOVER PROTECTION

Due to the high voltage in this tube(CRT), internal flashover flashover from destroying the cathode or other internal circuits. These spark gaps shall be connected with each electrode in socket PCB assembly.

occurrs.

Protection must be provided using spark gap to prevent

5. THEORY OF OPERATION

GENERAL

The circuit of this monitor could be devided into four sections. One of them is power supply section, and the others are the-interface, sweep video, and CDT drive section.

POWER CIRCUIT

The switching mode power supply is adopted for this circuit. The chassis (secondary side) is insulated from the power source (primary side) by the transformer By the winding of the transformer TlOl connected to the collector of cuit, the ICI01 is submitted to negative feed back and it operates as a blocking oscillator. When the voltage of power source or load

IClOl.

When the voltage applied to pin2 is varied, the conducting time of IClOl is varied to compensate output voltage for the change.

Which makes output voltage of

The range of operating frequency is

+B Voltage regulator drcuit

1~103

is a regulator for

comes from FBT pin6 and outputs signals with different duty times and frequencies.

there signals drive

controling

IC103

TlOl

stabilized.

+B Voltage of each mode supplied to

to control the adjusment of +B Voltage of each mode to

curredt

22kHz-70kHz.

is varied, it is detected by the winding and the voltage is applied to pin2 of

IClOl

and the other winding connected to the control cir-

FBT(T301)

pin2.

ICI04

FBT Pin2.

TlOl.

detects the Level of Pulse which

Interface circuit

This is a circuit for detecting the polarities and frequencies of the sync. pulse from computer, and for the automatic control of each mode. It uses Micro controller unit, which has three functions as follows.

MCU identifies each mode by processing the received frequency and polarity of the sync. from computer.

*MCU

controls buffer and decoder IC to output proper signal for picture size, frequency, and picture position.

*When monitor is turned on or mode is changed, mute function is operated.

VIDEO DRIVE CIRCUIT

The R. G. B input signals with analog level are applied to the pre-amplifrer LMt203. This section amplifies the output signal of a generator enough to dirve a video output circuit. Video gain is controlled by the DC voltage of pin12 and DC bias is controlled by the DC voltage of the pin 15, 19 and 24. Clamping pulse is applied to pin14 through IC

VIDEO OUTPUT CIRCUIT

The

LM2416T

The

LM2416T,

It is designed to swing large voltage n a short duration. The dirven signals are applied tp CDT cathodes.

DEFLECTION CIRCUIT

IC has 3 channels of R. G. B in one chip.

the CRT video dirver,

502(MCU

a large signal amplifier with wide bandwidth.

IC).

This circuit has two cal power amplifier.

KS. IC301

is a monolithic IC for horizontal and vertical sync processing. And

IC201

is a monolithic IC for verti-

1. Vertical Deflection Circuit. The

vertrcal

sync. signal with negative polarity is applied to pin 14 of IC 301. The vertical frequency of the oscillator can be controlled by the voltage at pin 12 of IC 301. And it canbe varied vy adjusting V-HOLD volume The vertical The vertrcal linearity is controlled by the voltage at pin 17 of IC 301. The ramp The IC 201 is a power Vertical position is determined by the DC adjusting V-SHIFT volume(VR905). Horizontal Deflection Circuit.

7-2

The horizontal sync. signal with negative polarity is applied to pin4 of controlled by the voltage at pin 1 of IC 301. And it can be varied by adjusting H-HOLD volume

The flyback pulse is fed to pin 8 of The phase of horizontal saw-tooth wave is compared with that of fly back pulse and the

IC301.

By adjusting H-phase control(VR904) the horizontal position of picture is varied. The horizontal frequency oscillation is obtained from pin3 of The horizontal output anode and focus vollages as well as several secondary supplies. A

diode

SlDE

PlNCUSt-liON CORRECTOR

herght

is controlled by the voltage at pin 16 of

srgnal

from pin 15 of IC 301 is applied to pin 1 of IC 201.

amplifier.

cuttent

flowing through vertical DY. So the picture is shifted to top or bottom by

IC302

for AFC(Automatic Frequency Control).

IC302

and is fed to the next horizontal drive circuit.

circurt

uses a resonant

modulator circuit IS used for east/west correction and for setting horizontal size.

flyback

IC301.

IC301

The horizontal frequency of the oscillator can be

system to drive the deflection yoke that generates the anode the

horrzontal

(VR301,

(VR302).

sync.

VR305)

srgnal

at AFC circuit of

Thus

circuit compensates the east/west distortion. The signal processing for east/west correction The vertical ramp signal from the The output section of A positive horizontal The horizontal width is determined by the voltage of

(VR902).

IC701

flyback

IC301

is a class-D(PWM) power amplifier. pulse from T301 is divided by resistor R703 and applied to pin 9 of

done in

is AC coupled through

PROTECTION CIRCUIT

If a failure, voltage of D300 will be Increased by the FBT(T301). Then the protectron When thes happens, the Therefore In order to restart

whrch

causes high voltage increased, occurrs(such as opened sweep capacitor or failed power regulator), the cathode

occurrs

turnrng

on Q301 as a result of the breakdown of

oscrllator

signal coming from

operatron,

the monitor must be turned off and on agaim.

IC701.

C205

to the east/west distortion amplitude control,

IC701.

pinl0,

which is varied by the setting of the gorizontal width control volume

D300.

IC301

can no longer dirve Q305. then the set is turned off.

VR901.

+ 35 hidden pages