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CHASSIS: TB1238
MODEL:
21RBS3Ve
B
B
B
S
S
S
3
3
3
21RBS3Wn
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
Page 3
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CONTENT
TB 1238 SERIES I2C BUS CONTROL INSTRUCTION ....................................................................... 4
TYPICAL FAILURE ANALYSE............................................................................................................6
VARIOUS PARAMETERS OF INTEGRATED CIRCUIT.................................................................. 20
CIRCUIT DIAGRAM............................................................................................................................ 22
EXPLODED VIEW................................................................................................................................ 23
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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TB 1238 SERIES I2C BUS CONTROL INSTRUSTION
3. The way go into the factory mode
Step 1. Press the numeric keys, switch to the position 12
Step 2. Press the numeric keys again, switch to the position 38
Step 3. Press the MENU key to call up the POS.LOCK menu
Step4. Press the MUTE key
Step5. Press the numeric key to input the password 1, 2, 3, 8. Then the TV will enter into the
factory mode while the "M" displayed on the top of the screen.
4. Under adjusting mode, you can select the item you want by pressing the “ ” keys and you
can adjust the value of the items when you press the “ ” keys.
5. If the adjusting is default, please restore the data as previous or adjust according the table as
follows.
No Item Value Meaning No Item Value Meaning
1 RCUT 20* Red cut-off 35 VP 60 01 60Hz vertical center
2 GCUT 38* Green cut-off 36 HITS FD 50Hz/60Hz vertical size
3 BCUT 44* Blue cut-off 37 VLIN 0A Vertical linearity
4 GDRV 40* Green drive 38 VSC 06 Vertical S correction
5 BDRV 40* Blue drive 39 VLIS FF 50Hz/60Hz vertical linearity
6 CNTX 3F Contrast maximum 40 DPC 00 50Hz pillow distortion correction
7 BRTC 30 Brighter center 41 DPCS 00 50/60Hz pillow distortion
correction
8 COLC 50 Color center 42 KEY 00 50Hz keystone distortion
9 TNTC 40 Tint center 43 KEYS 00 50/60Hz keystone distortion
10 COLP 10 Color center of PAL 44 WID 00 50Hz horizontal size
11 COLS 40 Color center of
SECAM
12 SCNT 0F Sub-contrast 46 VCP 00 Vertical compensation
13 CNTC 20 Sub-contrast center 47 CNR 00 Coner correction
14 CNTN 08 Sub-contrast minimum 48 HCP 00 Horizontal compensation
15 BRTX 20 Sub-bright maximum 49 SBY 08 SECAM B-Y
16 BRTN 20 Sub-bright minimum 50 SRY 08 SECAM R-Y
17 COLX 7F Sub-color maximum 51 RAGC 16 R.F. AGC
18 COLN 00 Sub-color minimum 52 AFT 40* Auto frequency tune
19 TNTX 35 Sub-tint maximum 53 HAFC 00 AFC Gain
20 TNTN 28 Sub-tint minimum 54 V25 55 25 percent Volume
21 ST 3 3F TV-3.58 sharpness 55 V50 6F 50 percent Volume
22 SV 3 3F AV-3.58 sharpness 56 BRTS 00 Sub-bright
23 ST 4 20 TV-4.43 sharpness 57 VM 2 30 (CTS-763A)
24 SV 4 3F AV-4.43 sharpness 58 MOD0 21 Mode 0
26 SHPN 1A Sharpness minimum 60 MOD2 0C Mode 2
27 TXCX 36 OSD contrast
maximum
45 WIDS 00 50/60Hz horizontal size
06 For 14 and 21 inches Mode 1 25 SHPX 30 Sharpness maximum 59 MOD1
17 For 25 and 29 inches Mode 2
61 SELF
VCO
7G* Self-diagnosis VCO
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
Page 5
No Item Value Meaning No Item Value Meaning
28 RGCN 16 OSD contrast
minimum
29 VMO 7C VCD data 0 63 SELF
62 SELF
AGC
69* Self-diagnosis AGC
75* Self-diagnosis bright center
BRTC
30 VM 1 00 VCD data 1 64 SELF
00* Self-diagnosis contrast center
CNTC
31 HPOS 0B Horizontal position 65 SELF
32* Self-diagnosis tint center
TNTC
32 VP 50 04 50 Hz vertical center 66 SELF
23* Self-diagnosis color center
COL
33 HIT 19 50 Hz vertical size 67 OSD 00 OSD width adjustment
34 HPS 02 50/60Hz horizontal
68 OPT 27 Option
center
69 MOD3 07 Language 70 ZOOM
3F Zoom in height
IN HIT
71 ZOOM
0b Zoom out height
OUT
HIT
5
Note:
1. The items with * in value are very special, do not adjust them at random. The items(1-5) are
used to debug white-black-balance of set.
2. The general secret code is 2175.
3. If you find the threadlike disturbance on the top of picture, please adjust the VM 2 in the items
and make its value come to 34.
4. When E PROM does not work, please exchange the same model chip with data that the
manufacture has already input. 2
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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TYPICAL FAILURE ANALYSE
1. Three-None (no raster, no picture, no sound)
This failure is mainly caused by big-power circuit such as power supply, horizontal scanning, vertical
scanning.
The detail checking and repairing steps are as follow.
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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0V
0V
>130V
Test the voltage of C461
0V
Check R552,V553,VD561
VD515,V511,V512,R555
115V
N201 pin 8 voltage
115V
<50V
N0 variation
Cut off W320
Others
9V
Normal
Low
Test other voltage such
as 180V,24V and 12V
300V
Check Z203,C209,N201
2V
N201 pin32 voltage
V553,VD561,RP551
R569,V706,V512
C513,VD515,V511
0V
Check the voltage
of V513 collector
24V
V431 pin C voltage
Check VD 551, C561
Check T501
Check VD553,C563,R434
C434,T402,C432,V431,R550
Check R431,V431
Others
No variation
Recover W320,unplug
XS 401 for a while,then
test the voltage of C561
115V
Check V513
>1V
115V
Check V432 pin C voltage
Check V432,T401
T402,VE 601
0V
Check T401,V432,R435 Check T401
Check L407, L408,
VE601,VD411,C443
Check if V706
is broken down
0V
Voltage of C507
Check if V513 collect-emitter
was broken down
No
Yes
Check R502,F501, power
0V
300V
Check V513,V512,F501,R502,VD503
switch, AC cord and plug
0.6V
Test voltage of V513 base
Yes
N701 Pin42
Test the voltage
Check if it get right
when cut off V706
Check T501,VD517
of
C515,C517,VD552
VD553-VD555
V432,C435,C436
T401,C443,VD411
4.5-5.5V
CPU has sent the
power-off signal
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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2. Two-None (no picture, no sound)
The failure shows that the set does not display the picture but it has noise wave or blue background or
OSD on the screen. This means that the circuits of power supply, horizontal scanning, vertical scanning
and video amplification are normal and they are not considered in the repairing. The failures are mainly
in the small signal processing circuits.
Before checking these circuits, a kind of practical test method is introduced .It is called Signal-input
way .The detail is described as follow:
W e can use the resistance function of an analog multimeter, connect the red pole (negative in ohm
scope) on the circuit board ground, then touch softly the test point with another pole (black pole) in
ohm scope meanwhile observe the reactivity on the output device.
Note: In the TV test, we mainly observe the noise wave on the CRT and listen to the noise voice liking
as Ka....Ka from the loudspeakers.
a. No picture
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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No picture
9
Check RF signal input and adaptor
No
Check if U101 has input signal
Yes
Out of the 0-33V range
Check R576,C573,VD573,UPC574
Check the VT voltage when auto searching
In the 0-33V range
Check the voltage on the C704
Check L103,N203,U101
0V
Check the MB voltage on U101
5V
Check R120,R121,R714
R715,N701,U101
0V
The voltage between band1 and band2 vary
from 0V to 5V or not when auto searching
Yes
Check R706,R705,VD701,R704
R703,V701,R701,R702,N701
Yes
<2V
Check R104,R204,C206,U101,N201
Exam the voltage of AGC on U101 without antenna
>3.8V
0V
Test the voltage on pin 1,3,17,28,36 of N201
9V
Check L206 ,C122, N101,C120, R258 ,R569
C554,VD554,N201,L209,L201,R218,VD205
Test the voltage on pin46 of N201
0V
Check N203,L203,N201
5V
Observe if there is snow-noise-wave disturbance on the CRT via using Signal-input way by touching pin 6 and pin8 of N201
No
Yes
Observe if there is snow-noise-wave disturbance on the CRT via using Signal-input way by touching pin 47 of N201
No
Observe if there is snow-noise-wave disturbance on the CRT via using Signal-input way by touching pin 35 of N201
33V
The voltage on the C573
=33V
0-33V
Check R707,C103,U101
Yes
Check N203,L203,C239,N201
Yes
No variation
Check if the voltage on pin28 of N201 is 4.6V
<2V
Check C244,C245,
N201,L205,R228
Yes
Observe if there is snow-noise-wave disturbance on the CRT via using Signal-input way by touching pin 39 of N201
The voltage on pin4 of N201
2.38V
The voltage on pin13 of N701
0V
Check R720,N701,R202
0V
Check N201
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
No
Check C211,R252-255,V804,V204,V202,N201
ZN01,LN01,RN03,RN02,R244,R240,R227
Yes
No
Test if there is the sync signal on the pin36 of N701
Yes
Check R222,R223,V201,C228,R229
No
Check R780,C715,N701,N201
Observe if there is snow-noise-wave disturbance on the CRT via using Signal-input way by touching pin 18-20 of N201
No
Check R206-R208,VD202-VD204,XS601,N201
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b. No sound
In this kind of failure, first of all we should observe if there is the picture on the CRT . It proves the
small signal circuit to work correctly with the picture on the CRT and we only check the sound signal
processing and sound amplification circuit. The repairing method (B1) may be referred without picture.
The detail checking and repairing steps are as follow.
Note:
Before repairing, assure that the volume is on and the state of set is in TV.
Model No: 21RBS3Ve_21RBS3Wn
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<9V
No
Yes
9V
9V
Yes
Check C253,C250,C251,N201
No
Check 9V -power supply
No
The voltage on pin16 of N801
No
No
The voltage on pin9-11 of N801
9V
The voltage on pin 10 of N301
Check V806,R750,R737
No
Check BL301,BL302,N301
Hear if there is the voice liking Ka...ka in the loudspeaker via using Signal-input way by touching pin53 of N201
Yes
Hear if there is the voice liking Ka...ka in the loudspeaker via using Signal-input way by touching pin1 of N201
Hear if there is the voice liking Ka...ka in the loudspeaker via using Signal-input way by touching pin2 and pin5 of N801
Check C251,ZN04,R245
<5V
Hear if there is the voice liking Ka...ka in the loudspeaker via using Signal-input way by touching pin4,pin15 of N801
Hear if there is the voice liking Ka...ka in the loudspeaker via using Signal-input way by touching pin1 and pin3 of N301
Check R562,C565,VD555,N301
Hear if there is the voice liking Ka...ka in the loudspeaker via using Signal-input way by touching pin9 of N301
Yes
Yes
Check C303,R352
Check R111,V102,R112,C201,N201
R362,V303,C807
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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3. Only horizontal line in the middle of the screen
If vertical deflection circuit does not work, this kind of failure will happen. In deflection yoke, there
only has horizontal sweeping. The electron beam in the CRT only moves in the horizontal orientation
so form this failure.
(While checking horizontal and vertical deflection circuit s failure, we have better to use an
oscilloscope.)
Model No: 21RBS3Ve_21RBS3Wn
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Check N401
Check VD 401, N4 01
Abnormal
0V
Normal
The waveform on the pin24 of N201
Abnormal
24V
Normal
The voltage on pin3 of N401
Measuring the waveform on pin4 of N401
Measuring the waveform on pin2 of N401
Abnormal
Check N201,C216,C217,R260
Check R259,C403,N401
Normal
Measuring the waveform on the deflection yoke
Abnormal
Normal
The deflection yoke on the CRT
Check R402,L401,R406
R407,C409,XS401
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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4. Only vertical line in the middle of the screen
This is a dangerous failure. It probable causes flashover and smoking inside the set. Don t let your TV
work for a long time as this failure appears.
Because the electron beam can not move in the horizontal orientation, the failure should be in the
horizontal deflection circuit. We mainly check the open-circuit fault in horizontal deflection circuit.
The detail checking and repairing steps are as follow:
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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Repair CRT
Yes
No
No
Vertical line
The horizontal yoke is opened or not
Whether XS401 is opened
Yes
Check L407,L408,VD411,C443, especial in inductive components and connector
Check if there is bad solder between
XS401,and the main board
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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5. CPU does not work
In television, remote-control system is similar with the computer system. In theory, it can work if it
holds two conditions as follow:
1) The power supply: In general, it is 5V, the error is not above 10% and the disturbance
pulse is as small as possible.
2) The clock pulse: In TB 1238 circuit, the clock pulse is generated by pin31/ pin32 of
N701 and a 8M crystal oscillator.
Television s remote-control system also needs reset circuit that can preset the values in internal register.
The circuit around pin33 of N701 is called auto-reset circuit. If CPU detects errors in resetting, it will
come to the state of programme protected.
The detail checking and repairing steps are as follow:
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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Check N705
>5V
Check T501,VD556,C556
Check alternant voltage
on secondary coil of T502
<5V
Check T501
<7V
<5V
Check the voltage on the positive pole of C566
N701 does not work
The voltage on the pin42 of N701
Yes
<4.98V
<4.98V
=3.6V
5V
Check R754, V705, R752
Observe if there is sine wave on t he pin31
or pin32 of N701 with an oscilloscope
No
Check the voltage on the pin33 of N701
4.98V
Check Z701,N701
4.98V
Check N701
Check the voltage on the emitter of V705
Check the voltage on the positive pole of VD 704
<3.6V
Check R741
Check R753,VD704
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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6. No OSD (On Screen Display)
This failure is usually cause by the circuit of character generated and located. Most of reasons are that
the horizontal and vertical flyback pulse signals do not come to CPU.
We can judge this failure by measuring the wave of the character in an oscilloscope.
The detail checking and repairing steps are as follow:
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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No OSD
No
Observe if there is character wave on the pin14-17 of N201
Yes
Yes
Check R727-R732,C707-
C709,C210-C212
No
Observe if there is character wave on the pin22-24 of N701
Yes
Observe if there is oscillating wave on the pin28-29 of N701
Check N701
Yes
No
Check the wave on the base of V703,V704
No
Check V703,V704, R747
R748,R740,R735
Yes
Check the wave on the pin5 o f FBT
Check the wave on the pin7 of N401
No
Check C720,R766,R736,C711,R738,R739,C461,R410
Yes
No
Check FBT,N401
Check the horizontal and vertical flyback pulse on the pin26 and pin 27 of N701
Check N201
Check L701,N701
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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VARIOUS PARAMETERS OF INTEGRATED CIRCUIT
A. Pin voltage of N201
PIN 1 2 3 4 5 6 7 8 9
VOL. 4.9V 3.5V 4.1V 2.4V 0V 2V 2V 1.2V 4.2V
FUNC. DE
EMP A-OUT
PIN 10 11 12 13 14 15 16 17 18
VOL. 2.4V 3.8V 0V 0V 3V 3V 3V 9.1V 2.5V
FUNC. APC XCO Y/C
PIN 19 20 21 22 23 24 25 26 27
VOL. 2.4V 2.5V 6.1V 4.6V 5.3V 1V 1.8V 3.9V 4.1V
FUNC. G
OUT BOUT
PIN 28 29 30 31 32 33 34 35 36
VOL. 9.3V 3.8V 0.4V 4V 2V 0V 1.3V 5.3V 3V
FUNC. H
VCCIDCW
PIN 37 38 39 40 41 42 43 44 45
VOL. 2.5V 2.5V 3.1V 7.3V 1.6V 0V 3.2V 2.3V 2.8V
FUNC. B-Y INR-Y INY IN H AFC EXT
PIN 46 47 48 49 50 51 52 53 54
VOL. 5.4V 3.8V 4.6V 0V 8.2V 8.2V 9.1V 4.7V 5.6V
FUNC. Y/C
VCC
PIN 55 56
VOL. 4.3V 3.5V
FUNC. EXT
A IN FMDET
IF
DET
IF
VCC
GND
ABL V
FBP INSYNC
LOOP
FIL
AFT
GND
FB R IN G IN B IN RGB
RAMP
OUT
VCD
GND
IF
GND
V FB V
H
OUT
Y IN
VC 01 Vc02 VCO
IF IN 1IF IN 2 RF-
V AGC SCL SDA
OUT
DEF
GND
DIG
GND
SCP CVBS
TV Y
IN
VCC
AGC
VCC
OUT
BLA
CK
DET
SIF
IN
IF AGC
R OUT
DIG VCC
C IN
REG
Model No: 21RBS3Ve_21RBS3Wn
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B. Pin voltage of N701
PIN 1 2 3 4 5 6 7 8 9
VOL. 0V 4.8V 5V 0V 3.8V 3.8V 0V 5V 5V
FUNC. GND VT RMT
MUTE VOL1 VOL2 POWER LED BAND1
OUT
PIN 10 11 12 13 14 15 16 17 18
VOL. 0V 5V 5V 2.4V 0V 4.8V 4.9V 0V 0V
FUNC. BAND2 SCL0 SDA0 AFC IN KARA
SW
KEY IN 1KEY IN 2 KARA
CLK
KARA
DATA
PIN 19 20 21 22 23 24 25 26 27
VOL. 0V 0V 0V 0V 0V 0V 0V 4.4V 4.8V
FUNC. SGV KARA
GND OSD R OSD G OSD B OSD Y HD VD
ENA
PIN 28 29 30 31 32 33 34 35 36
VOL. 5V 5V 0V 1.4V 2.2V 5V 0.6V 4.5V 4.8V
FUNC. OSC1 OSC2 TEST X IN X OUT RESET TV/AV REMOTE H SYNC
PIN 37 38 39 40 41 42
VOL. 3.8V 4V 0.2V 0.2V 0V 5V
FUNC. SCL1 SDA1 S
IF 1 IF 1 VCC
VIDEO
C. Pin voltage of N401 (TA8427)
PIN 1 2 3 4 5 6 7
VOL. 0V 14.1V 27.2V 0.93V 0.83V 26.8V 1.33V
FUNC. GND V OUT PUMP
POWER
INPUT PHASE
COMPEN.
POWER
SUPPLY
PULSE OUT
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
Page 22
Pin Voltage of N701(Unit:V)
r
o
22
Pin Voltage of N201(Unit:V)
Pin Voltage of N401(Unit:V)
Significance to product safety . It is particularly recommended that only the parts specified in se
Manual be used for components replacement pointed out by the mark.
The values of the components indicated by a mark in this circuit diagram have special
6. This circuit diagram covers a basic or representative chassis by only. The re may be some comp
or partial circuit differences between the actual chassis and the circuit diagram.
.
3
,n=10
6
6
. M=10
3
. k =10
. M represents M
Notice:
1. All resistance values are in ohms. k represents k
4. The rated voltage of all capacitances is 50V unless otherwise noted.
5. Product safety should be considered when a component replacement is made in any area of a receiver.
2.The rated power of all resistance is 1/6W unless otherwise noted.
3. All capacitance values without unit are in pF . m represents mF, n represents nF ,m=10
CIRCUIT DIAGRAM
Model No:21RBS3Ve_21RBS3Wn
Version 1.0
n
Page 23
EXPLODED VIEW
23
Model No: 21RBS3Ve_21RBS3Wn
Version 1.0
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