GoldStar CB21T20S Schematic

NO RASTER

CHECK +B

at D821 cathode

Is the voltage at pin37

& 12 of IC501 8V?

Check

FUSE of AC line

Check the voltage

of C805

Check the voltage

of pin9

Check pin40

of IC501(H-out)

Check Q402

collector waveform

Check T401

& each pin voltage

Is the voltage at pin37

& 12 of IC501 8V?

Check &replace

IC501

Check &replace

IC501

Check &replace

IC501

Check the in/out

of IC841

Check u-COM

pin1 low?

Check /replace

Q802

Check /replace

D804,IC801,R801,802

Check /replace

Fuse,DB801,IC801

Check /replace

DB801,R851

Normal Abnormal

Yes

Yes

Yes

Yes

No

No

No

No

No

No

OK

254~380V

Open

0V

NO TELETEXT

Check the

voltage of IC701 pin19

Check

IC701& IICBus Line

Check 5V Supply

Line of IC701

0V

OK

OK

Check

CVBS signal

at IC701 pin9

Check / Replace

Q701, X701, & IC501

Not OK

OK

NO RASTER / SOUND OK

Check the

Heater voltage of CPT

(6 ≠ 6.5Vrms)

Check

FR704, FR901

P302, & P903

Check

FBT T701

Check the

Heater pulse of FBT

T701

Check

Ik Current of

IC501, pin18

Not OK

OK Not OK

Check/Replace

CPT Board

Components

Check
IC501, ZD904
P501, & P902

OK Not OK

OK

Check

HV, Screen voltage of

CPT

Check

FBT T701

Not OK

NO SOUND / PICTURE OK

Check the voltage of SMPS

25V at pin5 of IC601

Check the voltage

swing of pin2 of IC501

Normal(20~25V)Abnormal

Check demodulated

signal of pin15 of IC501

Check demodulated
of input pin of IC601

Check/Replace IC01

Check/Replace of

FR824,D824,FR601

Check/Replace IC501

Check/Replace IC601

NO PICTURE / NO SONUD

Is any OSD displayed?

Check receiving system in MENU

& excute Auto-program.

Yes

OK

Not OK

Check IC01 pin9,10

(V-Sync, H-Sync)

Check IC01 pin36,37

(XLC, EXLC)

& IC01

No

Go to

NO SOUND /

PICTURE OK

Does the Auto-program

operate properly.

Store in manual-program MENU

Check 5V, 33V & IIC Bus Line

of TUNER

Is the CVBS signal OK.

( IC501 pin6 )

Check R,G,B signal

at IC501 pin19,20,21

Check

5V, 33V &

IIC Bus Line

Yes

Not OK

Not OK

OK

Check / Replace

TUNER, IC501

Not OK

OK

Check / Replace

CPT Board component

Check

CVBS singal Line

& IC501

Check IC01 pin30,31,32

(R,G,B)

OK

Not OK

- 1 -

Y Safety Precautions

1. It is safe to adjust after using insulating transformer
between the power supply line and chassis input to
prevent the risk of electric shock and protect the
instrument.

2. Never disconnect leads while the TV receiver is on.

3. Don't short any portion of circuits while power is on.

4. The adjustment must be done by the correct appliances.
But this is changeable in view of productivity.

5. Unless otherwise noted, set the line voltage to
230Vac

!10%, 50/60Hz.

Y Test Equipment required

1. Multimeter (volt meter)

2. Oscilloscope

:

RF AGC (Automatic Gain Control) Adjustment

The RF AGC was aligned at the time of manufacture for
optimum performance over a wide range conditions.
Readjustment of RF AGC should not be necessary unless
unusual local conditions exist, such as ;

1) Channel interference in a CATV system.

2) Picture bending and/or color beats, which are unusually
due to excessive RF signal input when the receiver is too
close to a transmitting tower or when the receiver is
connected to an antenna distribution system where the RF
signal has been amplified. In this case, the input signal
should be attenuated (with pad or filter) to a satisfactory
level.

3) Picture noise caused by "broadcast noise" or weak signal.
If the broadcast is "clean" and the RF signal is at least
1mV (60dBu), the picture will be noise free in any area.

Adjusting RF AGC to one end of rotation will usually cause a
relatively poor signal to noise ratio;
Adjusting to the other end of rotation will usually cause a
degradation of over load capabilities resulting in color beats or
adjacent channel interference.

: Screen Voltage Adjustment

1) Press TV/AV Key to get AV Mode.

2) Connect the probe of oscilloscope to the RK (Red
Cathode) of CPT Board.

3) Adjust Screen Volume of FBT so that the waveform is the
same as below figure.

: Focus Adjustment

NOTE: This adjustment should be performed after warming

up for 10 minutes.

1) Tune the TV set to receive an inactive channel station.

2) Adjust the Focus control of FBT for best overall focus.

Adjustment

1. Connect RF signal (65dB!0.2dB) and turn on the TV.
[ Standard adjustment Channel

- EU 05 Ch. (f

rf = 175.25MHz) : CK, CL, CB

- EU 41 Ch. (f

rf = 631.25MHz) : CI

2. Press OK buttons on TV set and Remote Controller at the

same time to get into SVC-0 mode.

3. Press Channel UP/DOWN button on the Remote Controller

several times to find AGC??.

4. Press Volume UP/DOWN button until the AGC Voltage is

the same as the Table below.

5. Press OK(Y) button to memorize the data.

Test Point : AGC TP (J05)
Adjust : Remote Control

Test Point : RK (Red Cathode of CPT Board)
Adjust : Screen Control of FBT

Model

System

Tuner P/N

Marker

AGC Voltage

CK-

PAL/SECAM-B/G,D/K

6700VPF005B

LGEC

2.3! 0.1V

CL-

PAL/SECAM-B/G,LL'

6700VPF005A

LGEC

2.3! 0.1V

Model

System

Tuner P/N

Marker

AGC Voltage

CB-

PAL-B/G

6700VPF005B

LGEC

2.3! 0.1V

CI-

PAL-I/I

6700VPF005A

LGEC

2.1! 0.1V

Test Point : Observing Display
Adjust : Focus control of FBT

ADJUSTMENT

The waveform of AV Mode

V

200

150
100
50
GND

50V/DIV. 0.5usec.

Black­Level(DC)

150V

- 2 -

: Deflection Data Adjustment (Line SVC-1)

NOTE: To enter SVC mode, press "OK" buttons on both TV set

and the Remote control at the same time.

1. Preparation for Deflection Adjustment

1) At SVC mode, press the Yellow colored button.
If the Remote Controller doesn't have the Yellow button, you
should use a Service Remote Control (105-201G) and press
SVC button.
And then, deflection data adjustment OSD (SVC1 mode) will
be displayed.

2) Press Channel UP/DOWN button for desirous function
Adjustment.

3) Press Volume UP/DOWN button to adjust the data.

2. Deflection Adjustment Procedure

1) Vertical Adjustment

Slect VS and adjust until the mechanical center of CPT and
that of screen coincides and select VA and adjust to coincide
the inner circle of screen with outer frame of CPT.

2) Horizontal Adjustment

Select HS and adjust until the mechanical center of CPT and
that of screen coincides.

3) Vertical S Correction Adjustment

Select SC and adjust until top-bottom side pincushion are
equal.

4) Press OK(Y) button to memorize the data.

3. Deflection Initial Setup Data

: White Balance Adjustment.(LINE SVC-0)

NOTE : This adjustment should be performed after screen voltage

adjustment.

1) Tune the TV set to receive an 100% white pattern.

2) Press OK(Y) buttons on TV set and remote controller at the
same time to get into SVC mode.

3) Press PSM(RED) button on remote controller. (Standard
picture)

4) Press Channel UP/DOWN button for desirous function
adjustment.

5) Adjust VOL+ or VOL- button for GG031.

6)

Adjust VOL+ or VOL-button in each status of "Rg--"/"Bg--" for
X=293

!

8, Y=295!8 with color analyzer.

7) Press OK

(Y)

button to memorize the adjustment data.

Status

RG
GG
BG

Range

0~63
0~63
0~63

Initial Data

28
31
25

RemarkAdjustment

R-Drive
G-Drive
B-Drive

VL
VS

VA
HS
SC

38
23
40
30
11

Status Default

38
23
40
30
11

21" SEB

38
19
36
32
11

20" SEB

- 3 -

: OPTION Adjustment (SVC MODE:OPTION-1,

OPTION-2)

NOTE: When the EEPROM has been replaced, the Option data

should be restored as the function of individual system
and specification.

1) Press OK buttons on both TV set and Remote Controller at
the same time to get into SVC mode.

2) Press the Yellow button several times to find OPTION-1 or
OPTION-2.

3) Input the correspond OPTION data referring to Table below
with the numeric buttons 0~9.

Table 1. OPTION 1 Function

Table 2. Specifications for OPTION-1 data

20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63

CL-Model
CK-Model
CB-Model
CI-Model
for BUYER'S
request

AV 2

TOP

ACMS

HOTEL

SYSTEM

Option

OPTION Data SYSTEM HOTEL ACMS TOP AV 2

Code

00
01
10
11

0
1
0
1
0
1
0
1

0
1
2
3
4
5
6
7
8

9
10
11
12
13
14
15
16
17
18
19

00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
01
01
01
01

0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0

0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0

0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1

0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1

Function Remark

B+L (BG+LL')
B+D (BG+DK)
BG
II
W/O HOTEL
For HOTEL
ACMS Off
ACMS On
TOP Off
TOP On
AV 2 Off
AV 2 On

OPTION Data SYSTEM SCART EYE UBB AV2

01
01
01
01
01
01
01
01
01
01
01
01
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11

0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1

1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1

0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1

0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1