Changhong Electric 21NF55, 21PF93 Service Manual

FILE NO. SM-CTV-O-131

COLOR TELEVISION

SERVICE MANUAL

MODEL NO. 21NF55/21PF93

CHASSIS NO. EX-1A1

Please read this manual carefully before service

TABLE OF CONTENTS

SPECIFICATIONS............................................................................................................. 1

SAFETY INSTRUCTIONS AND MAINTENANCE......................................... 2

X-RAY RADIATION PRECAUTION.......................................................................................... 2

SAFETY PRECAUTION.............................................................................................................. 2

PRODUCT SAFETY NOTICE.................................................................................................... 3

SAFETY SYMBOL DESCRIPTION...........................................................................................3

MAINTENANCE............................................................................................................................ 4

ADJUSTMENTS.................................................................................................................. 5

SET-UP ADJUSTMENTS........................................................................................................... 5

CIRCUIT ADJUSTMENTS.......................................................................................................... 8

STRUCTURE AND CHASSIS FUNCTION DESCRIPTION.................... 14

STRUCTURE BLOCK DIAGRAM............................................................................................. 14

BLOCK DIAGRAM FOR SUPPLY VOLTAGE SYSTEM...................................................... 15

CHASSIS DESCRIPTION............................................................................................................16

SERVICE DATA .................................................................................................................17

TECHNICAL DATA OF KEY ICS...............................................................................................17

SERVICE DATA OF KEY ICS ....................................................................................................37

REPLACEMENT OF PARTS.......................................................................................................41

APPENDIX

1. CIRCUIT DIAGRAM

4. FINAL ASSEMBLY DIAGRAMS

3. FINAL WIRING DIAGRAMS

2. PRINTED CIRCUIT BOARD LAYOUTS

WAVEFORMS OF KEY ICS .......................................................................................................35

SERVICE MANUAL

SPECIFICATIONS

Model Number 21NF55 21PF93

Color

RF system

Video system PAL4.43, NTSC3.58, NTSC4.43, PAL-M, PAL-N (50/60Hz)

Receiving
channel

Programs preset 236(0-235)
Antenna input

Picture tube (Approx.)
Effective screen dimensions
Audio output (THD≤7%)

Power source 150-250V ~, 50/60Hz
Weight (Approx.) 24kg 25kg
Dimensions

(W×H×D) (Approx.)
Rated power consumption 69W

Note: Designs and specifications are subject to change without notice.

system
Sound
system

VHF
UHF
CATV

PAL4.43, NTSC3.58, NTSC4.43, SECAM

B/G, I, M, D/K

C1～C12 (49.75-85.25MHz, 168.25-216.25MHz)

C13～C57 (471.25-863.25MHz)

Z1～Z7 (111-167MHz)

Z8～Z35 (223-447MHz)

75Ω(unbalanced)

406×305mm

3W+3W

585×460×480mm 577×459×480mm

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SERVICE MANUAL

INSTRUCTIONS FOR SERVICE SAFETY AND MAINTENANCE

WARNING: BEFORE SERVICING THIS CHASSIS, READ THE “X-RAY RADIATION PRECAUTION”,
“

SAFETY PRECAUTION”AND “PRODUCT SAFETY NOTICE”INSTRUCTION BELOW.

X-RAY RADIATION PRECAUTION

1. The EHT must be checked every time the TV is serviced to ensure that the CRT does not emit
X-ray radiation as result of excessive EHT voltage. The maximum EHT voltage permissible in any
operating circumstances must not exceed the rated value. When checking the EHT, use the High
Voltage Check procedure in this manual using an accurate EHT voltmeter.

2. The only source of X-RAY radiation in this TV is the CRT. The TV minimizes X-RAY radiation, which
ensures safety during normal operation. To prevent X-ray radiation, the replacement CRT must be
identical to the original fitted as specified in the parts list.

3. Some components used in this TV have safety related characteristics preventing the CRT from
emitting X-ray radiation. For continued safety, replacement component should be made after
referring the PRODUCT SAFETY NOTICE below.

4. Service and adjustment of the TV may result in changes in the nominal EHT voltage of the CRT
anode. So ensure that the maximum EHT voltage does not exceed the rated value after service
and adjustment.

SAFETY PRECAUTION

WARNING: REFER SERVICING TO QUALIFIED SERVICE PERSONNEL ONLY.

1. The TV has a nominal working EHT voltage. Extreme caution should be exercised when working
on the TV with the back removed.

1.1 Do not attempt to service this TV if you are not conversant with the precautions and procedures for
working on high voltage equipment.

1.2 When handling or working on the CRT, always discharge the anode to the TV chassis before
removing the anode cap in case of electric shock.

1.3 The CRT, if broken, will violently expel glass fragments. Use shatterproof goggles and take extreme
care while handling.

1.4 Do not hold the CRT by the neck as this is a very dangerous practice.

2. It is essential that to maintain the safety of the customer all power cord forms be replaced exactly
as supplied from factory.

3. Voltage exists between the hot and cold ground when the TV is in operation. Install a suitable
isolating transformer of beyond rated overall power when servicing or connecting any test
equipment for the sake of safety.

4. When replacing ICs, use specific tools or a static-proof electric iron with small power (below 35W).

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SERVICE MANUAL

5. Do not use a magnetized screwdriver when tightening or loosing the deflection yoke assembly to
avoid electronic gun magnetized and decrement in convergence of the CRT.

6. When remounting the TV chassis, ensure that all guard devices, such as nonmetal control buttons,
switch, insulating sleeve, shielding cover, isolating resistors and capacitors, are installed on the
original place.

7. Replace blown fuses within the TV with the fuse specified in the parts list.

8. When replacing wires or components to terminals or tags, wind the leads around the terminal
before soldering. When replacing safety components identified by the international hazard symbols
on the circuit diagram and parts list, it must be the company-approved type and must be mounted
as the original.

9. Keep wires away from high temperature components.

PRODUCT SAFETY NOTICE

CAUTION: FOR YOU PROTECTION, THE FOLLOWING PRODUCT SAFETY NOTICE SHOULD BE
READ CAREFULLY BEFORE OPERATING AND SERVICING THIS TV SET.

1. Many electrical and mechanical components in this chassis have special safety-related
characteristics. These characteristics are often passed unnoticed by a visual inspection and the
X-ray radiation protection afforded by them cannot necessarily be obtained by using replacements
rated at higher voltages or wattage, etc. Components which have these special safety
characteristics in this manual and its supplements are identified by the international hazard
symbols on the circuit diagram and parts list. Before replacing any of these components read the
parts list in this manual carefully. Substitute replacement components which do not have the same
safety characteristics as specified in the parts list may create X-ray radiation.

2. Do not slap or beat the cabinet or CRT, since this may result in fire or explosion.

3. Never allow the TV sharing a plug or socket with other large-power equipment. Doing so may result
in too large load, causing fire.

4. Do not allow anything to rest on or roll over the power cord. Protect the power cord from being
walked on, modified, cut or pinched, particularly at plugs.

5. Do not place any objects, especially heavy objects and lightings, on top of the TV set. Do not install
the TV near any heat sources such as radiators, heat registers, stove, or other apparatus that
produce heat.

6. Service personnel should observe the SAFETY INSTRUCTIONS in this manual during use and
servicing of this TV set. Otherwise, the resulted damage is not protected by the manufacturer.

SAFETY SYMBOL DESCRIPTION

The lightning symbol in the triangle tells you that the voltage inside this product may be
strong enough to cause an electric shock. Extreme caution should be exercised when

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SERVICE MANUAL

working on the TV with the back removed.
This is an international hazard symbol, telling you that the components identified by the
symbol have special safety-related characteristics.

FDA

This symbol tells you that the critical components identified by the FDA marking have

special safety-related characteristics.

UL This symbol tells you that the critical components identified by the UL marking have

special safety-related characteristics.

C UL This symbol tells you that the critical components identified by the C-UL marking have

been evaluated to the UL and C-UL standards and have special safety-related
characteristics.

VDE

This symbol tells you that the critical components identified by the VDE marking have

special safety-related characteristics.

MAINTENANCE

1. Install the TV set on a stable and level surface. Do not place the set near or over a radiator or heat
register, or where it is exposed to direct sunlight.

2. Do not install the TV set in a place exposed to rain, water, excessive dust, mechanical vibrations or
impacts.

3. Allow enough space (at least 10cm) between the TV and wall or enclosures for proper ventilation.

4. Slots and openings in the cabinet should never be blocked by clothes or other objects.

5. Please power off the TV set and disconnect it from the wall immediately if any abnormal condition
are met, such as bad smell, belching smoke, sparkling, abnormal sound, no picture/sound/raster.
Hold the plug firmly when disconnecting the power cord.

6. Unplug the TV set from the wall outlet before cleaning or polishing it. Use a dry soft cloth for
cleaning the exterior of the TV set or CRT screen. Do not use liquid cleaners or aerosol cleaners.

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SERVICE MANUAL

ADJUSTMENTS

SET-UP ADJUSTMENTS

The following adjustments should be made when a complete realignment is required or a new picture
tube is installed.
Perform the adjustments in the following order:

1. Color purity

2. Convergence

3. White balance

Notes:

①　 The purity/convergence magnet assembly and rubber wedges need mechanical positioning.
②　 For some picture tubes, purity/ convergence adjustments are not required.

1. Color Purity Adjustment

Preparation:
Before starting this adjustment, adjust the vertical sync, horizontal sync, vertical amplitude and
focus.

1.1 Face the TV set north or south.

1.2 Connect the power plug into the wall outlet and turn on the main power switch of the TV set.

1.3 Operate the TV for at least 15 minutes.

1.4 Degauss the TV set using a specific degaussing coil.

1.5 Set the brightness and contrast to maximum.

1.6 Counter clockwise rotate the R/B low brightness potentiometers to the end and rotate the green low
brightness potentiometer to center.

1.7 Receive green raster pattern signals.

1.8 Loosen the clamp screw holding the deflection yoke assembly and slide it forward or backward to
display a vertical green zone on the screen. Rotate and spread the tabs of the purity magnet
around the neck of the CRT until the green zone is located vertically at the center of the screen.

1.9 Slowly move the deflection yoke assembly forward or backward until a uniform green screen is
obtained.

1.10 Tighten the clamp screw of the assembly temporarily. Check purity of the red raster and blue raster
until purities of the three rasters meet the requirement.

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SERVICE MANUAL

Adjust the Angle (Vertical Lines)

Convergence Magnet Assembly

Deflection Coil

Dummy Wedge

Rubber Wedge

Glass Cloth Tapes

4-pole Magnet

Purity Magnet

Purity/Convergence
Magnet Module

6-pole Magnet

Adhesive

Deflection Yoke

Fig. 1

Fixed

Rotate Two Tabs At the
Same Time (Horizontal Lines)

Adjustment of Magnets

Fig. 2

2. Convergence Adjustment

Preparation:
Before attempting any convergence adjustment, the TV should be operated for at least 15 minutes.

2.1 Center convergence adjustment

2.1.1 Receive dot pattern.

2.1.2 Adjust the brightness/contrast controls to obtain a sharp picture.

2.1.3 Adjust two tabs of the 4-pole magnet to change the angle between them and red and blue

vertical lines are superimposed each other on the center of the screen.

2.1.4 Turn both tabs at the same time keeping the angle constant to superimpose red and blue

horizontal on the center of the screen.

2.1.5 Adjust two tabs of the 6-pole magnet to superimpose red/blue line and green line.

2.1.6 Remember red and blue movement. Repeat steps2.1.3-2..1.5 until optimal convergence is

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SERVICE MANUAL

Red/BLU

Red

pole Magnet

Red/BL

obtained.

2.2 Circumference convergence adjustment

2.2.1 Loosen the clamp screw holding the deflection yoke assembly and allow it tilting.

2.2.2 Temporarily put the first wedge between the picture tube and deflection yoke assembly. Move

front of the deflection yoke up or down to obtain better convergence in circumference. Push the
mounted wedge in to fix the yoke temporarily.

2.2.3 Put the second wedge into bottom.

2.2.4 Move front of the deflection yoke to the left or right to obtain better convergence in

circumference.

2.2.5 Fix the deflection yoke position and put the third wedge in either upper space. Fasten the

deflection yoke assembly on the picture tube.

2.2.6 Detach the temporarily mounted wedge and put it in either upper space. Fasten the deflection

yoke assembly on the picture tube.

2.2.7 After fastening the three wedges, recheck overall convergence and ensure to get optimal

convergence. Tighten the lamp screw holding the deflection yoke assembly.

BLU Red

BLU

4-pole Magnet Movement 6­Movement

Incline the Yoke up (or down) Incline the Yoke Right(or left)

Circumference Convergence by DEF Yoke

Fig. 3

3. White Balance Adjustment

Generally, white balance adjustment is made with professional equipment. It’s not practical to get
good white balance only through manual adjustment. For TVs with I2C bus control, change the bus
data to adjust white balance.

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SERVICE MANUAL

CIRCUIT ADJUSTMENTS

Preparation:
Circuit adjustments should be made only after completion of set-up adjustments.
Circuit adjustments can be performed using the adjustable components inside the TV set. For TVs with
I2C bus control, first change the bus data.

1. Degaussing

A degaussing coil is built inside he TV set. Each time the TV is powered on, the degaussing coil will
automatically degauss the TV. If the TV is magnetized by external strong magnetic field, causing
color spot on the screen, use a specific degausser to demagnetize the TV in the following ways.
Otherwise, color distortion will be shown on the screen.

1.1 Power on the TV set and operate it for at least 15 minutes.

1.2 Receive red full-field pattern.

1.3 Power on the specific degausser and face it to the TV screen.

1.4 Turn on the degausser. Slowly move it around the screen and slowly take it away from the TV.

1.5 Repeat the above steps until the TV is degaussed completely.

2. Supply Voltage Adjustment

Caution: +B voltage has close relation to high voltage. To prevent X-ray radiation, set +B voltage to
the rated voltage.

2.1 Make sure that the supply voltage is within the range of the rated value.

2.2 Connect a digital voltmeter to the +B voltage output terminal of the TV set. Power on the TV and set
the brightness and sub-brightness to minimum.

2.3 Regulate voltage adjustment components on the power PCB to make the voltmeter read 115±1V.

3. High Voltage Inspection

Measure voltages of test points on the main PCB with the digital voltmeter. Measure the CRT high
voltage with the high-voltage testing equipment and heater voltage with the high-frequency
effective voltmeter. The rated values are shown as below.

Table 1

Test Point Voltage Value (V)
Positive of C492 185V±5V
Filament pin of socket 6.3V±
21” CRT anode 25.5KV±1.2KV
Anode of 21” pure flat CRT (including Samsung, BMCC and Toshiba) 27.5KV±1.5KV
Anode of other 21” pure flat CRTs 26.5KV±1.5KV

Notes:

①　 Measure voltage of the related isoelectronic point if it’s difficult to measure a certain point in Table 1.
②　 Anode high voltage differs depending on CRTs used, which should be decided by engineers.

8

0.3

V

RMS

SERVICE MANUAL

4. Focus Adjustment

Caution: Dangerously high voltages are present inside the TV. Extreme caution should be
exercised when working on the TV with the back removed.

4.1 After removing the back cover, look for the FBT on the main PCB. There should be a FCB on the
FBT.

4.2 Power on the TV and preheat it for 15 min.

4.3 Receive a normal TV signal. Rotate knob of the FCB until you get a sharp picture.

5. Safety Inspection

5.1 Inspection for insulation and voltage-resistant
Perform safety test for all naked metal of the TV. Supply high voltage of 3000V AC, 50Hz (limit
current of 10mA) between all naked metal and cold ground. Test every point for 3 min. and ensure
no arcing and sparking.

5.2 Requirements for insulation resistance
Measure resistance between naked metal of the TV and feed end of the power cord to be infinity
with a DC-500 high resistance meter and insulation resistance between the naked metal and
degaussing coil to be over 20MΩ.

6. DESIGN/SERVICE mode

6.1 To enter the USER SERVICE mode

Caution: The user service mode adjustment can be changed only when service personnel adjust
the whole set data during servicing. As the control data have dramatic effects on functions and
performance of the TV, service personnel should not tell user how to
enter the SERVICE mode to avoid improper data settings.

6.1.1 Set the volume to 0. Then press and hold the MUTE button on

the remote control, and press the MENU button on the TV to

S

VS 0-3F 25

xxxxxxxx

enter the SERVICE mode. (In this case, the S mode cannot be
stored in the EEPROM. To exit from the S mode, turn off the TV set. )

6.1.2 After entering the S mode, Red “S”is displayed on the upper center of the screen and MENU1

is default. Use the POS+/- buttons to highlight an adjustment and the VOL+/- buttons to adjust
it. The adjusted data are immediately output and stored in the EEPROM

6.2 Bus data in the S mode

Table 1 Adjustment and Option Data in S mode

Item Adjustment Description Remarks

CORE 03 Coring (for some CPU only)
0-IF 20 Sound adjustment setting (for some CPU only)
5PAR/6PAR 1F Parallelogram correction (for large-screen only)

5BOW/6BOW 1F Curve correction (for large-screen only)

5HSH/6HSH

Set to the
optimal mode

Horizontal center in the TV mode for 50Hz/60Hz
For 50Hz, “5HSH” is displayed；for 60Hz, “6HSH” is
displayed.

9

*

(Continued)

SERVICE MANUAL

0

Chunghwa CRT

5EWW/6EWW 1F East-West correction (for large-screen only)
5EWP/6EWP 1F East-West parabola correction (for large-screen only)

5UCR/6UCR 1F Upper corner parabola correction (for large-screen only)
5LCR/6LCR 1F Lower corner parabola correction (for large-screen only)
5EWT/6EWT 1F Trapezoidal correction (for large-screen only)
5VSL/6VSL 1F Vertical slope (for large-screen only) *

5VAM/6VAM 1F

5SCL/6SCL

5VSH/6VSH

5VOF/6VOF

VX 19 Vertical zoom (for large-screen only)

Set to the
optimal mode
Set to the
optimal mode

Set to the
optimal mode

20 Red gun cutoff voltage *

Vertical amplitude; For 50Hz, “5VAM” is displayed；for
60Hz, “6VAM” is displayed.

S correction *

Vertical center in the TV mode for 50Hz/60Hz. For 50Hz,
“5VSH” is displayed；for 60Hz, “6VSH” is displayed.

OSD vertical center *

*

*

GRN 20 Green gun cutoff voltage *
WPR 1F Red gun drive voltage *
WPG 1F Green gun drive voltage *
WPB 1F Blue gun drive voltage *
YDFP/YDFN 07 PAL brightness delay time/ NTSC brightness delay time
TOP 10-1F UOC AGC *

TV audio output power can be adjusted by means of UOC
audio output amplitude. Generally, UOC audio output

VOL 26

IFFS 03（02） PIF (02-38.9MHz, 03-38MHz)
HDOL 04 Cathode drive level (typical: 04-07)
AGC 03 IF ACG speed

VG2B 3A

SBRI 1F Sub brightness
MBRI 30 Brightness Max.

amplitude is set to 26 for 21” models with stereo output of
3W+3W; 2C for 21” models with stereo output of 5W+5W;
24 for 14” models with mono output of 2WX2; 22 for 14”
models with mono output of 1WX2.

VG2 brightness setting(VG2B): 3A for 21” models;

2E for 14” models;
Contrast Max. setting (MCON): 30 for 21” Malaysia
Matsushita or BMCC CRT with ferrite mask;
MCON: 30; VG2B: 30, HDOL: 04 for 21”

(Continued)

***

1

SERVICE MANUAL

SCON 20 Sub contrast
MCON 30 Contrast Max.

SCOL 32 Sub color
OP1 BF Option set byte 1 ***
OP2 09 Option set byte 2 ***
OP3 FF Option set byte 3 ***
OP4 F6 Option set byte 4 ***
OP5 76 Option set byte 5 ***
OP6 3C Option set byte 6 ***
INIT EEPROM initialization
VG2 Adjusting screen voltage with VG2 *
VSD Vertical output off
STS0/1/2 System status byte

Notes:

①　 The items remarked with “*”, not affecting functions of the whole set, can be adjusted depending on models.
②　 The items remarked with “***”, affecting functions of the whole set, can be adjusted depending on functions of

models.

③　 To write in logo, use the ↓/↑buttons to highlight an adjustment and the ←/→ buttons to adjust.
④　 The data sheet may differ dependent on different models.
⑤　 The data sheet may differ dependent on different CRTs for the same model.

6.3 Option set

With remote control system software TDA935X, all options can be set in the SERVICE mode and
stored in EEPROM. Data related to picture, sound and geometric adjustment are also stored in
EEPROM.

Table 2 Function Option Bit Setting

Bit Item Description Data

0 OP_HOTEL Hotel mode (1: Yes, 0: No) 1

1 OP_236

OP1

OP2 0 OP_AVL AVL: 1: Yes 1

2 OP_NTSC NTSC color system options: 1: Yes, 0: No 1

3 OP_AV2

4 OP-SVSH S-Video terminal: 1: Yes, 0: No 1
5 OP-DVD DVD component input: 1: Yes 1
6 OP-RGB RGB input: 1: Yes, 0: No 1
7 OP-OSO Switch off in vertical overscan 1

Channels preset: 1: 236 channels

0: 100 channels

Two sets of AV inputs: 1: Two sets of separate AV inputs 0：Two
sets of parallel AV inputs or one set of AV inputs

(Continued)

1

1/0

11

12

OP3

OP4

OP5

SERVICE MANUAL

AV RF output: 1: RF output (for models with SCART jack

1 OP_RFTOAV

2 OP_NOT_1 0
3 OP_NOT_2 0

4 OP_NOT_3

5 OP_USER-LOGO

6 OP_ON-BLACK

7 OP_FSL Slicing level for vertical sync 0
0 OP_ENGLISH English 1
1 OP_FARSI Farsi or Czech 1
2 OP_ARABIC Arabic or Slovakian 1
3 OP_RUSSIAN Russian 1
4 OP_FRENCH French 1
5 OP_GERMAN German 1
6 OP_ITALY Italian, Indonesian or Hungarian 1
7 OP_SPANISH Spanish, Malay or Croatian 1
0 OP_FMWS Window selection of sound pll: small/large window 0

1 OP_DIRECT_SWIT

CH_ON

2 OP_HCO EHT tracking mode 1

3 OP_LOGO

4 OP_SOUND_DK Sound system-D/K option setting 1
5 OP_SOUND_BG Sound system-B/G option setting 1
6 OP_SOUND_I Sound system-I option setting 1
7 OP_SOUND_M Sound system-M option setting 1

0 OP_TUNER

1 OP_AUTO_LANG0
2 OP_AUTO_LANG1

1XX-English/Arabic
011-English/Farsi
010-English/Russian
001-English/Ukrainian
000- English/Paneuro
User LOGO setting prior to CHANGHONG LOGO: 1: Display

characters can be set by the VOL+/- buttons
Power-on auto test back selection:
1: Blue, 0: Black

Memory power-on (If turned off by the remote control, then the
TV is turned on by the remote control; if turned off by the MAIN
POWER SWITCH, then turned on by the MAIN POWER
SWITCH.) 1: Yes

Changhong logo display ： 1-Displayed without signal
reception；0-No

Tuner: 1: Philips-Tuner

0: Panasonic-Tuner

Outgoing language option setting: (OP-AUTO-LANG2/1/0):
English (000)

except EX-1A)

0: Monitor output (for models with RCA jack)

-NOT-3/2/1):

0/1

0

0

0

1

0

0

0
0

(Continued)

SERVICE MANUAL

13

OP6

Notes:

①　 Do not change the data marked with “ ” in “Data”column.
②　 Check if the color/sound systems conform to the specifications of different models after setting.

3 OP_AUTO_LANG2

4 OP_FORF 1

5 OP_FORS

6 OP_AVON If AV off, then AV on 1
7 OP_ONPOSITION With HOTEL mode preset, on position is fixed to POS1. 0
0 OP_AUTOTEST Auto test when power-on (set to 0 typically) 0
1 OP_PSNS Sensitivity 0
2 OP_BSCREEN Black screen when changing channels: 1-Yes；0-No 1
3 OP_SECAM SECAM color system option: 1: Yes 1
4 OP_DFL Disable flash protection 1
5 OP_SIF External SIF amplifier: 1: Yes, 0: No 1
6 OP_EXT_SIF0 1

7 OP_EXT_SIF1

Farsi (001)
Arabic (010)
Russian (011)
French (100)
German (101)
Italian or Indonesian (110)
Spanish or Malay (111)
Field frequency options (OP-FORS/FORF):

00- AUTO 60HZ, 01-KEEP LAST,

10-FORCE 60HZ, 11-AUTO 50HZ

Sound system options for external circuit (OP-EXT -SIF1/0):
D/K: 00，B/G: 01，I: 10，M: 11.
1: Sets sound system of external SIF as the appropriate one
and also sets sound system in the course of auto demo as the
appropriate one
0: Changes sound system in the course of auto demo.

0

1

0

SERVICE MANUAL

14

Tuner

A101

IF Pre-

Amplifier

+

SAWF

Analog Switc h

HEF4053

Video

Amplifier

Formed of

Microcontroller and small signal processor

UOC

CH05T0108

EEPROM
AT24C08

Audio Prec essor

TDA7449

H.Drive

V.OUT

TDA8356J

Audio Amp lifier

TDA7057AQ

H.OUT

FBT

T402

Power Supply Circuit

STR-F6654 or

STR-G5653

+3.3V+5V-1

+15V

+115V

CRT

Audio/Video

Input/Output

Band 1,2

Vt,AGC

From

Antenna

IIC BUS

Audio
Input

R

L

Speaker

150-250V~,50/60Hz

VY01-VY09

G RB

R e m o t e

Remote

Sensor

HS 0038

Circui for

Bu ttons On

The TV

c o n t ro l

STRUCTURE AND CHASSIS FUNCTION DESCRIPTION

1. STRUCTURE BLOCK DIAGRAM

Fig.4 Structure Block Diagram for EX-1A1 Chassis Series

SERVICE MANUAL

15

Regulator

V115

N441

N442

Regulator

V871,

VD882

FBT

T400

VD491

+190V

VD451

+45V

VD461

+16V

VD471

To CRT RGB PCB

To A100,N401

To N401

+8V

+5V-2

To A100

VD891

+115V

To N600

VD881 +15V-H

VD871 +15-S

+5V-1

To H Ou t
EEPROM
R/C Input

+3.3V

To N100

Keyboard

Switch

Transformer

T804

Power Regulat ion

and Control Circuit

STR-G5653/F6654

Bridge Rectifying

Filter

VD803~VD806

C802,C807

Line Filter

L801,C801,

C802

150-250V~,50/60Hz

Feedback Circuit

N801

Error Signal

To A100,

N100,

N650

2. BLOCK DIAGRAM FOR SUPPLY VOLT-AGE SYSTEM

Fig .6 Block Diagram for EX-1A1 Supply Voltage System

SERVICE MANUAL

16

3. CHASSIS DESCRIPTION

1). General Description

EX-1A1 chassis series are applied in 21NF55/21PF93 respectively which uses mainly Philips’
advanced UOC-ultimate chip TDA935X/6X/8X and I2C-bus controlled IC. With combination of
microcontroller and small signal processor, the TDA935X/6X/8X series feature high-integration,
high-performance-to-price ratio and high-reliability and advanced functions with fewer external
components, which provide much convenience for manufacturing and technical service.

2). The EX -1A1chassis series mainly use the following ICs and assemblies.
Table 3 Key ICs and Assemblies

Serial

No.

1 N100
2 N200 AT24C08 EEPROM

3 N401 TDA8356/N6 Vertical scan output stage circuit
4 N402 HEF4053 Analog switch
5 N600 TDA7057AQ Sound power amplifier
6 N650 TDA7449 Sound processor
7 N861 STR-G5653 Power supply circuit
8 A100 TDQ-5B6M Tuner

Position Type Function Description

CH05T0101
(TDA935X/6X/8X)

Microcontroller and small signal processor (UOC)

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SERVICE DATA

1. KEY ICS TECHNICAL DATA

1.1 Microcontroller and small signal processor TDA935X/6X/8X

The super chips TDA935X/6X/8X are good in pins compatibility. Differences among them are shown
as follows.

TDA9351（48K） PAL/NTSC/SECAM+1 PAGE TELETEST
TDA9350（48K） PAL/NTSC+1 PAGE TELETEST
TDA9361（64K） PAL/NTSC/SECAM+10 PAGE TELETEST
TDA9360（64K） PAL/NTSC+10 PAGE TELETEST
TDA9380（32K） PAL/NTSC
TDA9387（32K） NTSC

TDA935X/6X/8X PS/N2 series TV signal processor-Teletext decoder with embedded
？ -Controller

1) General Description

The various versions of theTDA935X/6X/8X PS/N2 series combine the functions of a TV signal
processor together with a ？ -Controller and US Closed Caption decoder. Most versions have a
Teletext decoder on board. The Teletext decoder has an internal RAM memory for 1or 10 page text.
The ICs are intended to be used in economy television receivers with 90 ?and 110 ?picture tubes.？ ？
The ICs have supply voltages of 8 V and 3.3 V and they are mounted in S-DIP envelope with 64
pins.
The features are given in the following feature list. The differences between the various ICs are
given in the table on page 4.

2) Features

TV-signal processor

● Multi-standard vision IF circuit with alignment-free PLL demodulator

● Internal (switchable) time-constant for the IF-AGC circuit

● A choice can be made between versions with mono intercarrier sound FM demodulator and

versions with QSS IF amplifier.

● The mono intercarrier sound versions have a selective FM-PLL demodulator which can be switched

to the different FM sound frequencies (4.5/5.5/6.0/6 .5 MHz).
The quality of this system is such that the external band-pass filters can be omitted.

● Source selection between ‘internal’ CVBS and external CVBS or Y/C signals

● Integrated chrominance trap circuit

● Integrated luminance delay line with adjustable delay time

● Picture improvement features with peaking (with variable centre frequency and positive/negative

overshoot ratio) and black stretching

● Integrated chroma band-pass filter with switchable centre frequency

● Only one reference (12 MHz) crystal required for the

● -Controller, Teletext- and the colour decoder

● PAL/NTSC or multi-standard colour decoder with automatic search system

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● Internal base-band delay line

● RGB control circuit with ‘Continuous Cathode Calibration’, white point and black level offset

adjustment so that the colour temperature of the dark and the light parts of the screen can be
chosen independently.

● Linear RGB or YUV input with fast blanking for external RGB/YUV sources. The Text/OSD signals

are internally supplied from the ？ -Controller/Teletext decoder

●

Contrast reduction possibility during mixed-mode of OSD and Text signals

● Horizontal synchronization with two control loops and alignment-free horizontal oscillator

● Vertical count-down circuit

● Vertical driver optimized for DC-coupled vertical output stages

● Horizontal and vertical geometry processing

● Horizontal and vertical zoom function for 16 : 9 applications

● Horizontal parallelogram and bow correction for large screen picture tubes

● Low-power start -up of the horizontal drive circuit

TV signal processor -Teletext decoder with embedded ？ -Controller TDA935X/6X/8X PS/N2
series

● -Controller

● 80C51 ？ -controller core standard instruction set and timing

●

1 s machine cycle？

● 16 - 128Kx8-bit late programmed ROM

● 3 - 12Kx8-bit DATA RAM (shared between Display, Acquisition and Auxiliary Ram)

● Interrupt controller for individual enable/disable with two level priority

● Two 16-bit Timer/Counter registers

● One 16 bit Timer with 8-bit Pre-scaler

● WatchDog timer

● Auxiliary RAM page pointer

● 16-bit Data pointer

● Stand -by, Idle and Power Down (PD) mode

● 14 bits PWM for Voltage Synthesis Tuning

●

8-bit A/D converter

● 4 pins which can be programmed as general I/O pin, ADC input or PWM (6-bit) output

Data Capture

● Text memory for 0, 1 or 10 pages

● In the 10 page versions inventory of transmitted Teletext pages stored in the Transmitted Page

Table (TPT) and Subtitle Page Table (SPT)

● Data Capture for US Closed Caption

● Data Capture for 525/625 line WST, VPS (PDC system A) and Wide Screen Signalling (WSS) bit

decoding

● Automatic selection between 525 WST/625 WST

● Automatic selection between 625 WST/VPS on line 16 of VBI

● Real-time capture and decoding for WST Teletext in Hardware, to enable optimized ？ -processor

throughput

●

Automatic detection of FASTEXT transmission

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● Real-time packet 26 engine in Hardware for processing accented, G2 and G3 characters

● Signal quality detector for video and WST/VPS data types

● Comprehensive teletext language coverage

● Full Field and Vertical Blanking Interval (VBI) data capture of WST data

Display

● Teletext and Enhanced OSD modes

●

Features of level 1.5 WST and US Close Caption

● Serial and Parallel Display Attributes

● Single/Double/Quadruple Width and Height for characters

● Scrolling of display region

● Variable flash rate controlled by software

● Enhanced display features including overlining, underlining and italics

● Soft colours using CLUT with 4096 colour palette

● Globally selectable scan lines per row (9/10/13/16) and character matrix [12x10, 12x13, 12x16

(VxH)]

● Fringing (Shadow) selectable from N-S-E-W direction

● Fringe colour selectable

● Meshing of defined area

● Contrast reduction of defined area

●

Cursor

● Special Graphics Characters with two planes, allowing four colours per character

● 32 software redefinable On-Screen display characters

● 4 WST Character sets (G0/G2) in single device (e.g. Latin, Cyrillic, Greek, Arabic)

● G1 Mosaic graphics, Limited G3 Line drawing characters

● WST Character sets and Closed Caption Character set in single device

Functional Difference Between The Various IC Versions
IC Version (TDA) 9350 9351 9352 9353 9360 9361 9362 9363 9364 9365 9366 9367 9380 9381 9382
9383 9384 9385 9386 9387 9388 9389

Table 4

20

3) Block Diagram

Fig.7 Block Diagram for TDA935×/6×8×PS/N2 with Mono Intercarrier Sound Demodulator

SERVICE MANUAL

SERVICE MANUAL

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Block Diagram for TDA935×/6×8×PS/N2 with QSS IF Sound Channel

Fig.8

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4) pinning

Table 5

SYMBOL PIN

DESCRIPTION

P1.3/T1 1 port 1.3 or Counter/Timer 1 input
P1.6/SCL 2 port 1.6 or I2C-bus clock line
P1.7/SDA 3 port 1.7 or I2C-bus data line
P2.0/TPWM 4 port 2.0 or Tuning PWM output
P3.0/ADCO/PWMO

5 port 3.0 or ADC0 input or PWM0 output
P3.1/ADC1/PWM1 6 port 3.1 or ADC1 input or PWM1 output
P3.2/ADC1/PWM2 7 port 3.2 or ADC2 input or PWM2 output
P3.3/ADC3/PWM3 8 port 3.3 or ADC3 in put or PWM3 output
VSSC/P 9 digital ground for μ-Controller core and periphery
P0.5 10 port 0.5 (8mA current sinking capability for direct drive of LEDs)
P0.6 11 port 0.6 (8mA current sinking capability for direct drive of LEDs)
VSSA 12 analog ground of Teletext decoder and digital ground of TV-processor
SECPLL 13 SECAM PLL decoupling

VP2 14 2nd supply voltage TV-processor (+8V)
DECDIG 15 decoupling digital supply of TV-processor
PH2LF 16 phase-2 filter
PH1LF 17 phase-1 filter
GND3 18 ground 3 for TV-processor
DECBG 19 bandgap decoupling
AVL/EWD

(1)

20 Automatic Volume Levelling/East-West drive output
VDRB 21 vertical drive B output
VDRA 22 vertical drive A output
IFIN1 23 IF input 1
IFIN2 24 IF input 2
IREF 25 reference current input
VSC 26 vertical sawtooth capacitor
TUNERAGC 27 tuner AGC output
AUDEEM/SIFIN1
DECSDEM/SIFIN2
GND2 30 ground 2 for TV processor
SNDPLL/SIFAGC
AVL/SNDIF/REFO/

AMOUT

(1)

(1)

28 audio deemphasis or SIF input 1

(1)

29 decoupling sound demodulator or SIF input2

(1)

31 narrow band PLL filter/AGC sound IF

Automatic Volume Levelling/sound IF input/subcarrier reference

32

output/AM output
HOUT 33 (non controlled)
FBISO 34 horizontal output
AUDEXT/
QSSO/AMOUT
EHTO

(1)

flyback input/sand castle output

35

external audio input/QSS intercarrier out/AM audio output (non

36

controlled)
PLLIF 37 EHT/overvoltage protection input
IFVO/SVO 38 IF-PLL loop filter
VP1 39 IF video output/selected CVBS output
CVBSINT 40 main supply voltage TV-processor (+8V)
GND1 41 internal CVBS input
CVBS/Y 42 ground 1 for TV-processor
CHROMA 43 external CVBS/Y input

AUDOUT/AMOUT

(1)

44 chrominance input (SVHS)
INSSW2 45 2nd RGB/YUV insertion input
R2/VIN 46 2nd R input/V (R-Y) input
G2/YIN 47 2nd G input/U input

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SYMBOL PIN

DESCRIPTION

B2/UIN 48 2nd B input/U (B-Y) input
BCLIN 49 beam current limiter input/(V-guard input, note2)
BLKIN 50 black current input/(V-guard input, note2)
RO 51 Red output
GO 52 Green output
BO 53 Blue output
VDDA

analog supply of Teletext decoder and digital supply of TV-processor

54

(3.3V)
VPE 55 OTP programming Voltage
VDDC 56 digital supply to core (3.3V)
OSCGND 57 oscillator ground supply
XTALIN 58 crystal oscillator input
XTALOUT 59 crystal oscillator output
RESET 60 reset
VDDP 61 digital supply to periphery (+3.3V)
P1.0/INT1 62 port 1.0 or external interrupt 1 input
P1.1/TO 63 port 1.1 or Counter/Timer 0 input
P1.2/INTO 64 port 1.2 or external interrupt 0 input

Notes

1)The function of pin 20, 28, 29, 31, 32, 35 and 44 is dependent on the IC version (mono intercarrier
FM demodulator/QSS IF amplifier and East-West output or not) and on some software control bits.
The valid combinations are given in table 5.

Table 6 Pin functions for various versions

IC version

East-West

Y/N

CMB1/CM

BO bits

AM bit - - - - - 0 1 - 0 1
Pin 20 AVL EWD AVL EWD

Pin 28 AUDEEM SIFIN1
Pin 29 DECSDEM SIFIN2
Pin 31 SNDPLL SIFAGC
Pin 32 SNDIR

Pin 35 AUDEXT AUDEXT QSSO AMOUT AUDEXT QSSO AMOUT
Pin44 AUDOUT Controlled AM or audio out

00 01/10/11 00 01/10/11 00 01/10/11 00 01/10/11

FM -PLL Version QSS Version

N Y N Y

(1)

REFO

(2)

AVL/SNDIF

(1)

REFO

(2)

AMOUT REFO

(2)

AMOUT REFO

(2)

Notes

1)When additional(external) selectivity is required for FM-PLL system pin 32 can be used as sound IF
input. This function is selected by means of SIF bit in subaddress 28H.

2)The reference output signal is only available for the CMB1/CMBO setting of 0/1. For the other setings
this pin is a switch output.