Akira CT-21FDS1 Schematic

CHASSIS:

A21T01(TB1238)

MODEL:

CT-21FDS1

Model No: CT-21FDS1 Version 1.0

CONTENT

GERAL DESCRIPTION.......................................................................................................................... 4

SAFETY INSTRUCTION ....................................................................................................................... 6

CIRCUIT ADJUSTMENT....................................................................................................................... 7

FAULT FINDING TREES, DIAGRAMS & OVERVIEWS................................................................. 14

VARIOUS PARAMETERS OF INTEGRATED CIRCUIT.................................................................. 22

ELECTRICAL PART LIST ................................................................................................................... 30

CIRCUIT DIAGRAM............................................................................................................................ 40

Model No: CT-21FDS1 Version 1.0

GENERAL DESCRIPTION

AKIRA AKTP01 is a CTV monolithic chassis currently developed by AKIRA Co. It introduces a monolithic IC TB1238AN developed by Toshiba Co. To carry out all the small signal processing TB1238AN is a kind of IC used by color TV in PAL/NTSC system, which is controlled by Inter IC Bus. Together with the SECAM decoder TA1275Z, it can form a signal processing circuit for multi-system color TV. This chassis is used in many fashionable TV receiver technologies, which makes the performance reach the advanced level of the world.

Figure 1 shows the block diagram of AKTP01(A21T01). Table 1 provides A21T01 mainly ICs and functions. Figure 2 shows the whole set power supply system for AKTP01(A21T01). Figure 3 shows the system control circuit of AKTP01(A21T01).

Table 1: A21T01 mainly ICs and functions Location D901 87CM38N-3GN5/

D902 AT24C08 EEPROM

N101 LA7910 Band decoder N252 CD4053BE TV/AV switching N203 CD4053BE AV1/AV2 Switch N201 TB1238AN Small signal processor (IF/VIDEO/CHROMA/DEF) N402 LA7830 Vertical output power amplifier N701 TA1275AZ SECAM decoder N202 CD4052BE Sound system switching N701 AN5270 Audio power amplifier (L) N711 AN5270 Audio power amplifier(R) A903 HS0038A Remote control receiver

Type

87CK38N-2B46

Function Description System control microprocessor

Model No: CT-21FDS1 Version 1.0

L OUT

R OUT

V OUT

L IN1

R IN1 V IN1

L IN2 R IN2

V IN2

TUNER

TUN101

KEY

REMOTE

RECEIVER

A903

MEMORY

(D902)

ST24C08

AC150-260V

50/60Hz

TV/AV switching N252 CD4053BE

AV1/AV2 switching

N203 CD4053BE

12 2 5

V10

REMOTE

Resistance

disturbance

C501L502

VD503-VD506

10 11

SAW

A B

Bridge

rectification

VOL

SCL1

SDA1

Filte r

SIF TRAPS Z235~Z238

SIF BPS

Z231~Z234

87CK38N-2B46

MICROCONTROLLOR

87CM38N-3GN5

D901

POWER SUPPLY

+300V

CIRCUIT

V512V513V511

T501VD515

AUDIO AMPLIFIER

N701 AN5270

12 14 15

SOUND SYSTEM SWITCH

N202 CD4052BE

VIDEO OUT

TV AUDIO

IF IN IF IN

SDAO SCLO

AFC IN

H.SYN

V23

IF VIDEO

(IF/VIDEO/CK\HROMA/DEF)

SMALL SIGNAL

PROCESSOR

TB1238AN

13~16

H OUT

R,G,B, Y/BL

N201

FIELD OUTPUT

POWER AMP.

N402(LA78040)

AUDIO AMPLIFIER

N711 AN5270

V251

V OUT

R-Y B-Y

SCP OUT

SID OUT

VIDEO

AMPLIFIER

V602,V612,V622

V.OU

SECAM DECODER

N251 TA1275AZ

SCREE

FOCUS

EHT

HEAT

19V 13V 24V

146

HORIZONTAL

DRIVE

V444

T401

HORIZONT

OUTPUT

FBT(T402)

BSC25

114

Model No: CT-21FDS1 Version 1.0

SAFETY INSTRUCTION

Warning: Before examining and servicing this chassis, read carefully the following safety instruction.

X-RAY RADIATION PRECAUTION

1. The EHT must be checked every time the receiver is serviced to ensure that the CRT does not emit X-ray radiation as result of excessive EHT voltage. The nominal EHT for this receiver is 22KV at zero beam current (minimum brightness) operating at AC 220V. The maximum EHT voltage permissible in any operating circumstances must not exceed 25KV. 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 receiver is the CRT. To prevent X-ray radiation, you should use the same type of CRT when replacing it.

3. Some components used in this receiver have safety-related characteristics preventing the CRT from emitting X-ray radiation. For continued safety, replacement component should only be made after referring the Product Safety notice below.

SAFETY PRECAUTION

1. The high voltage in the TV reaches to 22KV when the TV is in operation. Be more careful during opening the back cover.

a. The high voltage existing in the TV is very dangerous. Refer servicing to qualified

personnel only.

b. Before removing the high voltage cap. Discharge the anode of the CRT and the

chassis in case of electric shock.

c. Wear a pair of goggles when handling the CRT to avoid broken pieces damaging

your eyes.

d. Do not hold the CRT neck in case of causing damage to the CRT.

2. When the power cord needs replacing, use the same one as that provided by AKIRA factory.

3. Voltage exists between the hot and cold ground when TV is in operation. Install a separation transformer during repairing or connecting to any tester for the sake of safety. The power of the separation transformer should be beyond rated overall power.

4. When replacing a burnout fuse, use the one with the same specifications as the original.

5. When replacing old wire, wind new one round the shaft to weld. When replacing components with safety in performance, use the same type as that specified by AKIRA and install it in the former way.

6. Never place wire near high-temperature or high-voltage components.

SAFETY CAUTIONS FOR PRODUCTS

Many electric and mechanical components in AKPH01 /02 chassis have special safety performances, which are always neglected. Even if replacing them with some components with the same voltage and power, you can not get effective protection to X-ray. In the circuit diagram, these special electric components are indicated by the special mark U shadow. When replacing any of them, use the one with the same specifications as the original’s. Otherwise, it may cause X-ray radiation and damage to overall safety.

and on the

Model No: CT-21FDS1 Version 1.0

CIRCUIT ADJUSTMENTS

GENERAL INFORMATIONS

All adjustment are thoroughly checked and corrected when the receiver leaves the factory. Therefore the receiver should operate normally and produce proper color and B/W pictures upon installation. However, several minor adjustments may be required depending on the particular location in which the receiver is operated.

This receiver is shipped completely in carton. Carefully draw out the receiver from the carton and remove all packing materials. Power cord into a convenient 220 volts 50 Hz AC two pin power outlet. Turn the receiver ON. Check and adjust all the customer controls such as BRIGHTNESS, CONTRAST and COLOUR Controls to obtain natural color or B/W picture.

AUTOMATIC DEGAUSSING

A degaussing coil is mounted around the picture tube so that external degaussing after moving the receiver is normally unnecessary, providing the receiver is properly degaussed upon installation. The degaussing coil operates for about 1 second after the power to the receiver is switched ON. If the set is moved or faced in a different direction, the power switch must be switched off at least 30 minutes in order that the automatic degaussing circuit operates properly. Should the chassis or parts of the cabinet become magnetized to cause poor color purity, use an external-degaussing coil. Slowly move the degaussing coil around the faceplate of the picture tube, the side and front of the receiver and slowly withdraw the coil to a distance of about 2m before disconnecting it from AC source. If color shading still persists, perform the COLOUR PURITY ADJUSTMENT and CONVERGENCE ADJUSTMENTS procedures.

ADJUSTMENT MODE

Item

Measuring Equipment

Preparation Before Adj.

Model No: CT-21FDS1 Version 1.0

B+ adjustment, TV signal receiving

AKPH01 chassis

No. 5 Service Remote Controller

The set is turned on and work normally. No signal input

Adjustment procedure

1. Press S-PVOC key to set PIF-VOC self-adjusting.

2. OSD appears as below, after adjustment finished.

Self-adjusting Adjusting OK

Note: When the OSD appears ‘AFT NG’, it means that AFT adjusting is not good. Please check the chassis if there is circuit short or parts wrong fitting. If not, counter-clockwise or clockwise turn a ferrite core in T211 at 1/4 to 1/2 turn.

Item B+ adjustment, TV signal receiving

AFT AFT OK

Measuring Equipment

Preparation Before Adj.

AKTP01 chassis

TV SG (Signal Generator) Digital multi-meter

The set is turned on Connect the TV SG to RF input terminal of the set.

Adjustment procedure

1. Turn RP551 potentiometer to adjust B+ to specified voltage.

2. Check voltages for video out, vertical out, circuit work and audio power out as follow.

Video Out 145 188

Vertical Out 26 26

Circuit Work 13 13

Audio Power Out

Voltage (volt)

14 inch 21 inch

19 for 3W 22 for 5W

Tolerance

±5V

±1V

3. TV signal receiving

a. Press MENU key, to select POS.MEMORY item. b. Press V+ or V- key, to select SEARCH or AUTOMEMORY item, press P+ key to

start searching.

c. Press P+ or P- key to inspect the set if there is channel skipped, if so, searching again

by SEARCH as above described.

Model No: CT-21FDS1 Version 1.0

Item TV system adapting & AV in/output inspection

Measuring Equipment

Preparation before Adj.

AKTP01 chassis

SG (with NTSC3.58). User remote controller Dual trace oscilloscope

Input TV and AV signal

Inspection procedure

1. Input the TV signal which system is designated in technical specification.

2. Switch TV system to the set by pressing SYS key on user remote controller according to the TV system in SG. The picture and sound must be normal.

3. Press TV/AV key, to select VIDEO1 or VIDEO2 input. The picture and sound must be normal

4. AV output inspection. Load a 75Ωresistor to VIDEO output terminal, 1Vp-p video output signal that is from TV signal or from VIDEO1 or VIDEO2 input signal should be observed on the

oscilloscope. Load two 10K resistors separately to AUDIO R and L output terminals, two 0.7Vp-p audio output signal that is from TV or from AV input signal (stereo) should be observed on the oscilloscope.

Item General adjustment

AKTP01 chassis

Measuring Equipment

Preparation before Adj.

SG No.1 and No.2 service remote controller and user remote controller

Brightness, contrast and color should be set in standard Press PP key repeatedly to set the picture at MEMORY2 (in standard)

Adjustment procedure

1. Receive the monoscope pattern signal

2. Turn the focus adjusting VR to make the picture clear.

3. Press M-ON key on No.2 service remote controller to set the set into manufactory adjustment mode.

4. Adjust the picture size roughly by No.2 service remote controller.

5. Grid 2 voltage adjustment. Press key on No.1 service remote controller, to set the screen into a horizontal line. Clockwise turn the screen VR gradually until a horizontal line appears on the screen.

6. Press R+ or R- (with the red block), G+ or G- (with the green block) and B+ or B- (with the blue block) key respectively, to adjust a horizontal line appeared to the white colour.

7. Press key again and changing back to normal screen.

Model No: CT-21FDS1 Version 1.0

Item Focus adjustment

Measuring Equipment

Preparation before Adj.

AKTP01 chassis

Brightness, contrast and color should be set in standard

Adjustment procedure

1. Receive the cross-hatch pattern signal

2. Turn the focus adjusting VR watching the screen and adjust the vertical line of mark to make the most thin. Then the focus adj. VR is set as close low voltage side as possible. Stop the focus adj. VR at the point that focus is a bit worse at once, turn back to the left and then turn back to the right a little again.

To be fine H. line

V. line

Magnified drawing of part

Item White balance adjustment

Measuring Equipment

Preparation before Adj.

AKTP01 chassis

SG and white balance meter No.1 service remote controller

Warm up the set for more than 30 min. Brightness, contrast and color should be set in standard

Adjustment procedure

1. Receive the monoscope pattern signal.

2. Press G (G.DRIVE) key and B (B.DRIVE) key on No.1 service remote controller to select G-DRV and B-DRV respectively, then press + or – key to adjust the white balance at the directed value (which is according to the specification of factory’s adjustment)

3. Press R+ or R-, G+ or G- and B+ or B- key respectively to adjust the white balance of low light until the white balance of high and low light is good

Model No: CT-21FDS1 Version 1.0

Item RF. AGC adjustment

AKTP01 chassis

Measuring Equipment

Preparation before Adj.

SG and digital multi meter No.5 service remote controller

Connect a digital multi meter to TP101 point on the chassis

Adjustment procedure

1. Receive the color bar signal that is 87.5% modulation and 60dBu level

2. Press RF AGC key on No.5 service remote controller to select RF. AGC adjustment, press + or – key to adjust the voltage of RF AGC to 3.7±0.1V that is read on the digital multi meter.

Item Vertical height, linearity and Hor. position adjustment

AKTP01 chassis

Measuring Equipment

Preparation before Adj.

SG No.2 and No.3 service remote controllers

Brightness, contrast and color should be set in standard

Adjustment procedure

1. Receive the 5-circles pattern signal that is 50HZ vertical frequency.

2. Press V-LINE, V-SIZE, V-CENT and H-CENT key on NO.2 service remote controller respectively to select the vertical linearity, height, center (position) and horizontal center (position) adjustment, and then press + or - key to adjust the value of them respectively according to factory’s specification.

3. Receive the 5-circles pattern signal that is 60HZ vertical frequency

4. Press V-LINE, V-SIZE, V-CENT and H-CENT key on NO.3 service remote controller separately to adjust the vertical linearity, height, center and horizontal center as above item 3.

Item OSD position adjustment

AKTP01 chassis

Measuring Equipment

Preparation before Adj.

No.1 and No.5 service remote controller

Brightness, contrast and color should be set in standard

Model No: CT-21FDS1 Version 1.0

Adjustment procedure

1. Press D-MODE key on No.1 service remote controller to set the set into design mode adjustment.

2. Press or key to select OSD item, press or key to adjust the OSD to the center position on the screen or press RF AGC key on No.5 service remote controller and press + or – key to adjust the OSD position

3. Press D-MODE key again to quit design mode adjustment.

Item The functions of the set inspection

AKTP01 chassis

Measuring Equipment

Preparation Before Adj.

SG User remote controller and No.

The set is turned on

Inspection procedure

1. Receive the Philips pattern signal

2. Press PIC key on user remote controller to call the menu as adjusting picture quality. Adjust color, brightness, contrast, sharpness and tint (in NTSC) respectively and all adjustment should be right

3. Press V+ key to increase the sound volume, no distortion heard at maximum level, press V- key to decrease the sound volume, no sound heard at minimum level

4. Press POWER key to switch the set into standby status, at mean time the manufactory adjustment mode is cancelled.

5. Press POWER key again, the set should work in normal receiving mode.

6. Press X (mute), DISP (display), PP and SLEEP key respectively, the relevant function should be normal

7. Press S-OUT key on No.5 service remote controller to set default value that stored in E2PROM on the chassis for product shipment.

Model No: CT-21FDS1 Version 1.0

+ 27 hidden pages

Akira CT-21FDS1 Schematic

Specifications and Main Features

Frequently Asked Questions

User Manual