Akira CT-21XF9A Schematic

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CHASSIS: CN-9EA

MODEL:

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CT-21XF9A

Model No: CT-21XF9A
Version 1.0

3

CONTENT

Specifications .......................................................................................4

General description ..............................................................................5

Safety instructions .............................................................................. 11

Circuit adjustments ....................….................................................... 12

Set-up adjustment .............................................................................. 13

Service mode general instructions ...................................................... 15

Service mode adjustment ................................................................... 19

Main repairing flow diagram ..............................................................20

Main ICs description and repair data offering .................................... 26

Spare parts list .……………………………………………………….. 46

Appendix:
Exploded view 21BM32/21BM31…..………………………………...68
Circuit diagram ……………………………………………………….73
Print lay-out of main board …………………………………………...74

Model No: CT-21XF9A
Version 1.0

SPECIFICATIONS

RF system: Color system: PAIA.43, NTSC3.58, NTSC4.43, PAL-M, PAL-N
Sound system: D/K, I, M, B/G
Video system: PAL4.43, NTSC4.43, NTSC3.58, PAL-M, PAL-N (50/60Hz)
Receiving channel: VHF: Cl~C12 (49.75 ~ 85.25MHz, 168.25 ~ 216.25MHz)
UHF: C 13~C57 (471.25 ~ 863.25MHz)
CATV: Zl~Z7 (111.0 ~ 167.0MHz)
Z8~Z35 (223.0~447.0MHz)
Programs Preset: 236
Antenna. input: 75Ù (imbalance)
Picture tube: Effective screen dimension: 406mmx305mm; Flat-square tube
Audio output: Main channel: 5W+5W (THD=7%)
Power supply: AC 150~260V (50Hz

Weight: ~26kg
Dimensions: 566mm(w) x 455mm(h) x 480mm(d)
Power consumption: ~87W (AC 220V 50Hz)

Model No: CT-21XF9A
Version 1.0

)

4

GENERAL DESCRIPTION

Figure 1 shows the block diagram of CN-9 (21BM32).
Table 1 provides CN-9EA chassis main ICs and functions.
Figure 2 shows the whole set power supply system for CN-9EA chassis.
Figure 3 shows the system control circuit of CN-9EA chassis.

Table 1: 21BS32EA mainly ICs and functions

Location Type Mainly function

N001 CH08T0934 System control microprocessor
N002 AT24C08-10PI Memory
N945 HS0038A Remote control receiver
NM01 TC9028F-022 Remote control transmitter
N101 LA7910 Band decoder
N202 HEF4052 Sound system switching

Small signal processing

N201 TB 1238AN
N401 TA8403 Vertical output power amplifier
N601 TDA7057AQ Audio power amplifier
N701 TA1275AZ SECAM decoder
N602 HCF4066BE Audio TV/AV switching
NS01 TDA7449 Audio processor
NT01 SAA5261 Teletext processor
NT02 PCF8582 Memory

(IF/VIDEO/CHROMA/DEF)

5

Model No: CT-21XF9A
Version 1.0

11

SAFETY INSTRUCTION

WARNING: BEFORE EXAMINING AND SERVICING THIS CHASSIS, READ CAREFULLY
THE FOLLOWING SAFETY INSTRUCTIONS.

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

27.5kv at zero beam current (minimum brightness) operating at AC 220V. The maximum
EHT voltage permissible in any operating circumstances must not exceed 30KV. 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 27.5KV 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 chas-

sis in case of electric shock.

c. Wear a pair of goggles when handling the CRT to void 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 stated in this manual.

3. Voltage exists between the hot and cold ground when the 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 this manual 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 CN-9 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 ! , and on the shadow. When replacing any of them, use the one with
the same specifications as the originals. Otherwise, it may cause X-ray radiation and damage to overall
safety.

Model No: CT-21XF9A
Version 1.0

12

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 colour 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 colour 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 colour purity, use an external-degaussing coil. Slowly move the
degaussing coil around the faceplate of the picture tube, the sides and front of the receiver and slowly
withdraw the coil to a distance of about 2m before disconnecting it from AC source. If colour shading
still persists, perform the COLOUR PURITY ADJUSTMENT and CONVERGENCE
ADJUSTMENTS procedures.

POWER SUPPLY ADJUSTMENT

CAUTION: +B voltage has close relation to high voltage. To avoid X-ray radiation, +B voltage should
be to +115V.

1. Set RV801 to the mechanical center and AC power supply to 220±2V.

2. Connect a digital voltmeter to two pins of C822, and then turn on the TV.

3. Receive Philips test signal.

4. Adjust RV81 to make the voltmeter read 115±0.5V.

HIGH VOLTAGE EXAMINATION

CAUTION: No high voltage adjustment should be done in CN-9EA chassis.

1. Connect a precise high voltmeter to the second anode of the CRT.

2. Turn on the TV and set the brightness and contrast to minimum (i.e. set beam current of the
CRT to zero).

3. The high voltage tested should be 27.5 ± 0.5KV.

4. Set the brightness to minimum or maximum, and ensure high voltage not beyond limitation of
30KV in any case.

Model No: CT-21XF9A
Version 1.0

13

FOCUS ADJUSTMENT

1. Use the remote control to set the contrast to maximum and the brightness, chroma to medium.

2. Set H. V. lines near Philips picture center to thinnest with the focus adjustment potentiometer
on the FBT. After finishing adjustment, ensure that no poor focusing exist near the center or
around of the frame.

Before Adjusting After adjusting

SET-UP ADJUSTMENT

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

1. Colour purity

2. Convergence

3. White Balance (See page 17)

Note: The PURITY/CONVERGENCE MAGNET assembly and rubber wedges need mechanical
positioning. Refer to figure 6.

COLOUR PURITY ADJUSTMENT

NOTE: Before attempting any purity adjustment, the receiver should be operated for at least
fifteen minutes.

1. Demagnetize the picture tube and cabinet using a degaussing coil.

2. Set the brightness and contrast to maximum

3. Receive the green raster test signal.

4. Loosen the clamp screw holding the deflection coil and slide, the backward or forward to
provide vertical green belt (zone) in the picture screen.

5. Remove the Rubber Wedges.

6. Rotate and spread the tabs of the purity magnet (See figure 7) around the neck of the picture
tube until the green belt is in the centre of the screen.

7. Slowly move the deflection coil forward or backward until a uniform green screen is obtained.
Tighten the Clamp screw of the coil temporarily.

8. Check the purity of the red and blue raster.

Model No: CT-21XF9A
Version 1.0

15

CONVERGENCE ADJUSTMENTS

NOTE: Before a attempting any convergence adjustments, the receiver should be operated for at
least fifteen minutes.

CENTRE CONVERGENCE ADJUSTMENT

1. Receive the pane pattern test signal.

2. Set the brightness and contrast for well-defined pattern.

3. Adjust two tabs of the 4-Pole Magnets to change the angle between them (See figure 7) and
superimpose red and blue vertical lines in the centre area of the picture screen.

4. Turn the both tabs at the same time keeping the angle constant to superimpose red and blue
horizontal lines at the centre of the screen.

5. Adjust two tabs of 6-Pole Magnets to superimpose red/blue line (land green line. Adjusting
the angle affects the vertical lines and rotating both magnets affects the horizontal lines.

6. Repeat adjustments 3, 4, 5 keeping in mind red, green and blue movement, because 4-Pole
Magnets and 6-Pole Magnets have mutual interaction and make dot movement complex.

CIRCUMFERENCE CONVERGENCE ADJUSTMENT

1. Loosen the clamping screw of defection coil slightly to allow the coil to tilt.

2. Temporarily put a wedge as shown in figure 6. (Do not remove cover paper on adhesive part
of the wedge.)

3. Tilt front of the deflection coil up or down to obtain better convergence in circumference. (See
figure 8) Push the mounted wedge into the space between picture tube and the coil to fix the
coil temporarily.

4. Put other wedge into bottom space and remove the cover paper to stick.

5. Tilt front of the deflection coil right or left to obtain better convergence in circumference. (See
figure 8)

6. Keep the deflection coil position and put another wedge in either upper space. Remove cover
paper and stick the wedge on picture tube to fix the coil.

7. Detach the temporarily mounted wedge and put it in another upper space. Stick it on picture
tube to fix the coil.

8. After fixing three wedges, recheck overall convergence. Tighten the screw firmly to fix the
coil and check the coil is firm.

9. Stick three adhesive tapes on wedges as shown in figure 6.

SERVICE MODE GENERAL INSTRUCTIONS

1. ENTERING TO SERVICE MODE

Use the user remote receiver K10N-C1. Set the volume to minimum. Press the MUTE button on
Remote Control. Keep pressing the MUTE button, press MENU button on TV set until the
character D and an adjustment item appears on the screen.

2. SELECTING THE ADJUSTING ITEMS

Every pressing of the RED or GREEN button on remote control transmitter changes the
adjustment items in the following BUS DATA table.

Model No: CT-21XF9A
Version 1.0

17

Table 2 The BUS DATA FOR 21BM32

Number Adjustment Item Adjustment Function Type Data

1 BCUT Blue Dark Balance 60
2 RCUT Red Dark Balance 4F
3 GCUT Green Dark Balance 8D
4 MODE Factory data 20
5 OPT Option F3
6 OSD OSD position 06
7 ZHP 03
8 LANG FF

9 VM2 TB1238AN V/C/D mode data 80
10 UHF-H Factory ASM VT limit of UHF high byte 00
11 UHF-L Factory ASM VT limit of UHF LOW byte D8
12 VHFH-H Factory ASM VT limit of VHFH high byte 00
13 VHFH-L Factory ASM VT limit of VHFH low byte F0
14 VHFL-H Factory ASM VT limit of VHFL high byte 02
15 VHFL Factory ASM VT limit of VHFL low byte 10
16 SNUM 20
17 PNUM Protect number 7F
18 SELF COLN Self adjust COLC initial data 10
19 SELF TNTC Self adjust TNTC center initial data 00
20 SELF CNTC Self adjust CNTC initial data 20
21 SELF BRTC Self adjust BRTC initial data 80
22 SELF AGC Self adjust AGC initial data 20
23 SELF VCO Self adjust VCO initial data 80
24 SELF TB1231N P40UT select 00
25 BRTS Sub bright (difference) 00
26 V50 Volume 50% 57
27 V25 Volume 25% 3A
28 HAFC AFC gain 00
29 AFT PIF VCO center 48
30 RAGC RF AGC 28
31 SRY SECAM R-Y 08
32 SBY SECAM B-Y 08
33 VLIS Vertical line deflection of 50/60 Hz 0B
34 VSC Vertical S correction 0C

Model No: CT-21XF9A
Version 1.0

18

Number Adjustment Item Adjustment Function Type Data

35 HPS Horizontal centering difference of 50/60Hz 10
36 HIT Vertical line of 50 Hz 20
37 VP50 Vertical centering of 50Hz 05
38 HPOS Horizontal center of 50 Hz 0C
39 VM1 V/C/D mode data 1 9F
40 VM0 V/C/D data 0 3C
41 RGCN Text RGB contrast min 16
42 TXCX Text RGB contrast max 2A
43 SHPN Sub sharpness min (difference) 1C
44 SHPX Sub sharpness max (difference) 1A
45 SV4 Sub sharp center (other AV) 20
46 ST4 Sub Sharp Center (other TV) 20
47 SV3 Sub sharp center (3.5BTSC AV) 20
48 ST3 Sub sharp center (3.58NTSC TV) 20
49 TNTN Sub tint min (difference) 28
50 TNTX Sub tint max (difference) 28
51 COLN Sub color min 00
52 COLX Sub color max (difference) 35
53 BRTN Sub bright min (difference) 20
54 BRTX Sub bright max (difference) 20
55 CNTN Sub contrast min 08
56 CNTC Sub contrast center 20
57 SCNT Sub contrast 06
58 COLS Sub color center (SECAM) 40
59 COLP Sub color center (PAL difference) 00
60 TNTC Sub tint center 40
61 COLC Sub color center (NSTC) 40
62 BRTC Sub-bright center 30
63 CNTX Sub contrast max 3F
64 BDRV Blue light Balance 40
65 GDRV Green light Balance 40

Model No: CT-21XF9A
Version 1.0

19

3. ADJUSTMENT THE DATA

Pressing of the YELLOW or BLUE button on remote control transmitter will change the value of
data, in the range from 00 to FF. The variable range depends on the adjusting item.

4. EXIT FROM SERVICE MODE

Use the keyboard on remote control transmitter or TV set to turn off the TV once.

SERVICE MODE ADJUSTMENT

1. SUB-BRIGHTNESS

1. Receive colour signals.

2. Set the contrast to maximum and the brightness to medium.

3. Set the chroma to medium.
Enter the TV to the SERVICE mode. Select the BRTC item by pressing the item adjustment button
on the remote transmitter, and set the data to 30 by pressing the data adjustment button. Operate
the TV for 5 min in the mode.

4. Adjust the BRTC data until fuzzy picture does not appear on the high bright area of the screen and
too dim picture not on the low-bright area.

5. Set the contrast and brightness to maximum or minimum, and then test normal picture alternation.

6. If the picture does not become dark when the contrast and brightness are set to minimum, or not

become bright when set to maximum, then adjust the BRTC data to get normal picture.

2. WHITE BALANCE ADJUSTMENT

1. Turn on the TV and preheat it for over 7 minute.

2. Use the remote control to set the contrast to maximum and the brightness to medium.
Set the chroma to minimum.

3. Enter the TV to the SERVICE mode, and set the following data without changing other items.

RCUT ............4F

GCUT ............8D

BCUT ............60

GDRN ............40

BDRN ............40

4. Pull out the external antenna and press the MUTE button once on the remote control until a bright
horizontal line appears on the screen. Adjust the GCUT data to get 160V±0.5 green gun voltage
across the Y board.

5. Adjust the RCUT and BCUT data according to the given at Step 4 so that the bright horizontal line
turns to yellow, then to white.

3. HORIZONTAL CENTERING ADJUSTMENT

Enter the TV to the service mode, and receive Philips test signal. Select the HPOS or HPS item by
pressing the item adjustment button on the remote control, and adjust horizontal picture position in the
centre of screen by pressing the data, adjustment button.

4. VERTICAL CENTERING ADJUSTMENT

Enter the TV to the service mode, and receive Philips test signal. Select the VPS0 or VP60 item by
pressing the item adjustment button on the remote transmitter, and adjust vertical picture position in the
centre of screen by pressing the data adjustment button.

Model No: CT-21XF9A
Version 1.0

20

5. VERTICAL AMPLITUDE ADJUSTMENT

Enter the TV to the service mode, and receive pane test signals. Select the HIT item by pressing the
item adjustment button on the remote transmitter, and adjust vertical amplitude by pressing the data,
adjustment button so that vertical amplitude lacks a little. Continue to adjust vertical amplitude by
pressing the data adjustment button until the first bar on pane signal touches edge of screen.

6. HORIZONTAL AMPLITUDE ADJUSTMENT

Receive Philips test signals. Adjust the horizontal amplitude adjustment inductance L506 so that the
edge of the CRT covers the right and left borderlines of Philips picture by 1/3 grille.

7. BUS DATA INITIALIZATION

When the BUS DATA of TV is confused, enter the TV to the service mode. Press the SLEEP button on
the Remote Control will initialize the BUS DATAS for all adjustment items.

MAIN REPAIRING FLOW DIAGRAM

The following flow diagrams are for the corresponding troubleshooting, which can help you find the
causes for troubles. Check as the order shown on the flow diagrams, you can find the defective
component.

Model No: CT-21XF9A
Version 1.0