Awa w6900sf schematic

AWA

W6900S/SF

29”(74 CM) COLOUR TV WITH

INFRARED REMOTE CONTROL

SERVICE MANUAL

SAFETY INSTRUCTIONS

WARNING: BEFORE SERVICING THIS CHASSIS, READ THE "X-RAY

RADIATION PRECAUTION", "SAFETY PRECAUTION" AND "PRODUCT SAFETY

NOTICE" DESCRIBED BELOW.

X-RAY RADIATION PRECAUTION

1. Extremely high voltage of the picture tube may result in producing potentially hazardous X-RAY RADIATION.

To avoid such hazards, the high voltage must not be above the specified limit. The nominal value of the high voltage of this receiver is about 30.4 kV at zero beam current (minimum brightness) under 175-245V AC power source. The high voltage must, under any circumstances, not exceed about 36kV. Each time this receiver requires servicing, the high voltage should be checked according to the HIGH VOLTAGE CHECK procedure at the back of this manual. it is recommended to record the reading of the high voltage in the service record each time. Using an accurate and reliable high impedance and high voltage meter is quite important. Connect the NEGATIVE and POSITIVE probe of a high voltage meter to the "ground" and the high voltage anode cap of the picture tube respectively.

Picture tube high voltage anode cap

High impedance and high voltagh meter Chassis

Picture tube ground

HIGH VOLTAGE CHECK CONNECTION DIAGRAM

2. The only source of X-RAY RADIATION in this receiver is the picture tube. For ensuring the intensity of X-RAY RADIATION from the picture tube being within the specified safety limit, the replacement picture tube must be exactly the same type specified in the parts list.

3. Some parts in this receiver have special safety-related characteristics which would affect X-RAY

RADIATION protection. For safety, parts replacement should be carried out only after referring to the "PRODUCT SAFETY NOTICE" below.

PRODUCT SAFETY NOTICE Many electrical and mechanical parts in this receiver have special safety-related characteristics (directly relate to high voltage, high temperature or electric shock) which are not easily seen by visual inspection. Whenever replacing such components, make sure that the replacement parts can provide effective X-RAY RADIATION protection even though their high voltage and wattage can meet the specification of the original design. Such parts

can be identified by shading and marking with in the schematic diagram and the parts list. Before replacing any of these components, read the parts list in this manual carefully. Using substitute parts which do not have the same safety characteristics as the ones specified in the parts list may create excessive X-RAY RADIATION.

I2C BUS CONCEPT (1). Characteristics

1.1 I2C Bus consists of clock (SCL) and data (SDA) lines.

1.2 It transmits data among integrated circuits in full duplex mode.

1.3 It is composed of a main IC chip (CPU) and one or more sub-IC chips.

l The CPU mainly operates data transmissions and also generates clock signal. l The CPU also controls all sub-IC chips, making them work.

(2). I2C Bus Application in this TV unit

SDA SCL

In this TV unit, ICU1 is the main chip while ICU2, IC101 and other chips are regarded as sub-chips.

2.1 ICU1 (CPU) controls the functions of IC101 via the I2C bus between them.

2.2 The data of channel positions, BT voltage, band, AFT, clear, volume, power on/off, timer, color, etc. are

written into, stored in and read out from ICU2 via the I2C bus.

SAFETY PRECAUTION

1. High voltage of 27-32kV is always present inside this receiver when it is operating, so be cautious of electric

shock hazard while removing the back cabinet to process adjustment.

(A) Servicing should not be attempted by any person who is not very familiar with the required re-cautions

when working on this high-voltage equipment.

(B) Before removing the anode cap of the picture tube, discharge the high voltage potential from the picture tube

anode several times by short-circuiting the anode together with its ground to keep off electric shock hazard.

highly evacuated. When it is broken, danger may be caused because of the violent burst of its glass fragments.

2. If the fuse in this receiver is blown, replace it with the type specified in the chassis parts list or with the same

specifications (never use other types).

3. Whenever replacing with new components, twist the lead wires of the component together with the concerned

residual leads before soldering.

4. Whenever replacing with a new high wattage resistor (such as oxide metal film resistor) on any of the circuit

boards, keep the body of the resistor 10 mm above the circuit board.

5. Keep all connecting wires away from the components of high voltage or high temperature.

6. This receiver is designed to operate at AC 175-245V~50/60Hz, NEVER connect to DC supply or any other

power sources.

7. The main chassis of this receiver is perfectly isolated.

INSTALLATION AND SERVICE ADJUSTMENTS

GENERAL INFORMATION: Normally, this receiver have been thoroughly checked and adjusted before leaving the factory; therefore it should operate normally and produce perfect color and B/W pictures upon installation. However, several minor adjustments may be required according to the practical situation. This receiver is packed in a cardboard carton during transportation. Carefully draw it out from the carton and remove all packing materials. Plug the receiver's power cord into a convenient 175-245V 50/60Hz AC two pin power outlet. Check and adjust all the customer controls such as BRIGHTNESS, CONTRAST and COLOUR to obtain natural color or B/W picture.

AUTOMATIC DEGAUSSING :

Input Terminals (Video),

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 one hour in order that the automatic degaussing circuit operates properly. And then the receiver turned it again.

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 2 meters before disconnecting it from AC source. If colour shading still persists, perform the “COLOUR PURITY ADJUSTMENT” and “CONVERGENCE ADJUSTMENTS” procedures as mentioned later.

LOCATION OF CONTROLS AND SWITCHES

Front View (Front Configuration)

(2)Groups 2 of Audio/Video Input Terminals (Video), (Audio), (L/Mono),

S-VIDEO

AUDIO

VIDEOL/MONO

：

SUPER WOOFER

MENU Button

Rear View (Back Configuration)

ON OFF

Headphone Jack (3.5mm Dia, 16ohm)

SUPER WOOFER 8

EXT. SPEAKER 8

AUDIO(MONITOR) AUDIOVIDEOVIDEO

INT.

EXT.

ＭＥＮＵ

Standby (Red)

Super Woofer Out Terminals

Main Speakers Output Terminals

L/MONOL/MONO

Power

(Green)

Speaker Switch (EXT/INT)

(1)Group of Audio/Video (Audio), (L/Mono),(R)

(Monition) Tv Out Terminals (Video), (Audio), (L/Mono),(R)

Remote Control Unit

There are 38 buttons on the remote control. It operates with infra-red beam which is not affected by noise or other interferences. Make sure strong light never strikes on the infra-red receiver; otherwise, it would obstruct the remote control working normally with the TV unit. Do not drop or expose it to high temperature.

*16-17 (FOR GERMAN STEREO ONLY)

*19-36 (FOR TELETEXT ONLY)

1. NUMBER (0-9) BUTTONS

2. PROGRAM (UP/DOWN) BUTTONS

3. AV BUTTON

4. TV BUTTON

5. STANDBY BUTTON

6. PERSONAL PREFERENCE BUTTON (PP)

7. SOUND MUTING BUTTON

8. STATUS BUTTON

9. VOLUME (UP/DOWN) BUTTONS

10. MENU BUTTON

11. RED (PICTURE MENU) BUTTON

12. GREEN (SOUND MENU) BUTTON

13. YELLOW (OTHER MENU) BUTTON

14. CYAN (INSTALL MENU) BUTTON

15. WHITE (TIME MENU) BUTTON

16. STEREO/MONO & DUAL I/II BUTTON

17. EFFECT BUTTON

18. SWAP BUTTON

19. SUBTITLE BUTTON

20. TXT. BUTTON

21. MIX. BUTTON

22. CANCEL BUTTON

23. HOLD BUTTONSIZE BUTTON

24. SIZE BUTTON

25. REVEAL BUTTON

26. TIME BUTTON

27. SUBCODE BUTTON

28. DIGIT ENTRY (0-9) BUTTONS

29. PAGE NUMBER UP / DOWN BUTTONS

30. PREVIOUS BUTTON

31. TOP/FLOP/SIMPLE BUTTON 32-35. COLOR BUTTONS

36. WHITE (INDEX) BUTTON

37. SERVICE BUTTON

２８

２９

３７

１６１７

２１２０２４２３

１９

１１１２

１３１４１５

１０

２２

１８３１

３０２６２７２５

３２３３３４３５３６

HOW TO DISASSEMBLE REMOTE CONTROL HAND UNIT (see Fig. 1)

1. Remove the battery cover and loosen the screws.

2. Open one side of the back cabinet to take it away from the front cabinet.

Fig. 1

METHOD OF REMOVING BACK CABINET (see Fig. 2)

Attn.: Before disassembling the back cabinet, first draw the power cord plug of the receiver from AC outlet.

1. Disconnect the antenna cable from the antenna terminal.

2. Loosen the 5 pieces of screw (A) used in fixing the antenna jack plate on the back cabinet.

3. Loosen the 9 pieces of screw (B) used in fixing the back cabinet to the front cabinet; then remove the back cabinet.

Screws(B)

Screws(A)

Fig.2

METHOD OF REMOVING MAIN CHASSIS (see Fig. 3 & 4)

After removing the back cabinet, proceed the following procedures accordingly.

1. To avoid electric shock hazard, discharge the high Fig.3 voltage potential from the picture tube anode several times by short-circuiting the positive anode of the picture tube with its ground before detaching the high-voltage anode cap.

2. Unsolder and detach the ground wire of the picture tube from the picture tube socket board.

3. Detach the picture tube socket board.

4. Detach the high-voltage anode cap.

5. Unplug Socket F, U, V, A, B, K or X and P.

6. Take out the chassis from the chassis holder.

High-volotage anode cap

Picture tube socket board

Screws(B)

METHOD OF REMOVING PICTURE TUBE (see Fig. 4)

MAIN CHASSIS PC BOARD

After taking out the chassis holder (main chassis), proceed the following procedures accordingly:

1. Turn the receiver down and let the screen of the picture tube face downward, and put it on a soft cushion.

2. Loosen the 4 pieces of nut used in fixing the picture tube on the front cabinet, remove the degaussing coil; then

use two hands to hold the edges of the picture tube tightly and draw it out.

3. Detach the ground wire of the picture tube which is attached to the lugs of the picture tube with springs.

Fig.4

SUGGESTION: Before servicing the chassis, please read through “X-RAY RADIATION

PRECAUTION", "SAFETY PRECAUTION" and "PRODUCT SAFETY NOTICE" at Page 2 & 3 of this manual.

GENERAL ADJUSTMENT INSTRUCTIONS This receiver is transistorized and special care should be taken when servicing. If not necessary, do not attempt any adjustments because the requirements of the procedures are very stringent. Read the following matters before attempting any adjustments. An isolation transformer should be used during any dynamic service to avoid possible electric shock hazard. The test equipment specified or their equivalent is required in having proper alignment. Using unsuitable equipment, which do not meet these requirements, may result in improper alignment. Correct matching of the equipment is essential. Failure of using proper matching will result in responses which cannot show the true operation of the receiver. Excessive signal by using a sweep generator can cause the receiver circuit overloaded. Overloading should be avoided to obtain a true response curve. Insertion of markers by using the marker generator should not cause the response curve distorted. The AC power line voltage should be accurately kept during alignment. During the process of alignment, the AC voltage should be kept in the range from 215V to 225V (50Hz). Do not attempt to connect or disconnect any wire while the receiver is in operation. Make sure the power cord is unplugged before replacing any parts in the receiver. Unless specified, start adjustments after the receiver is turned on for at least 30 seconds.

CHASSIS'S TOP VIEW

VRC2

VRC1

E-W CORRECTION PC BOARD

T902

VR 501

NOTICE:

1. Resistor

All resistors are of 1/8W Carbon Film type except those listed below. The unit of measure for resistor is OHM (K = 1,000 ohm, M = 1,000,000 ohm).

CARBON FILM RESISTOR

CARBON COMPOSITION RESISTOR METAL OXIDE RESISTOR +5% METAL OXIDE RESISTOR +2% FUSIBLE RESISTOR NON-INFLAMMABLE RESISTOR PTC THERMISTOR VARIABLE RESISTOR

2. Capacitor All capacitors are of 50V Ceramic type except those listed below. The unit of measure for capacitor is

FARAD (F) (UF = 0.000001 F, PF = UUF = 0.000001 UF)

CERAMIC CAPACITOR

TANTALUM CAPACITOR POLYESTER FILM CAPACITOR POLYPROPYLENE FILM CAPACITOR ELECTROLYTIC CAPACITOR TRIMMER CAPACITOR METAL POLYESTER FILM CAPACITOR

3. Unit of Measure: UH

4. Test Point

5. Marking of Ground Wire

: Ground wire of chassis (COLD) : Ground wire of external wire (HOT)

6. Voltage Measurement

The voltages at all points should be measured with a digital multi-meter, and the measuring conditions are as follows: Power Source: AC220V 50Hz Receiving Signal: Color Bar Signal All Control Buttons: in Normal Position

7. Waveform

The numeral in the small circle represents the number of waveform, refer to the waveform table.

8. It is easy to locate a connection point in the direction as indicated by arrow (↗).

9. The schematic diagram in this manual is drawn according to the original design. It may be slightly different from

the actual circuit of the receiver because of any change in the circuit subject to no prior notice.

Notice: This circuit has a transformer to isolate the power supply circuit from the majority of the other

circuit, and they can be identified in the schematic diagram by marking with "HOT" and "COLD”. Please note the followings .All circuits are "COLD" except power supply circuit.

(1) To avoid electric shock hazard, never touch the "HOT" and "COLD" circuit simultaneously. (2) Never short-circuit the "HOT" and "COLD" circuit to prevent the fuse or other components from burning. (3) Never connect any measuring equipment such as oscilloscope to both the "HOT" and "COLD" circuit at the

same time to prevent the fuse from burning. Also, connect the ground of the measuring equipment to the ground of the circuit being tested.

(4) Never fail to unplug the power cord of the receiver before taking out the chassis.

TEST EQUIPMENT :

EQUIPMENT SPECIFICATION High Impedance Voltmeter Having an impedance of at least 100 Kohm. Oscilloscope Volt sensitivity over 10mV input impedance over 1

Sweep/Marker Generator Output adjustable to at least 0.1 volts rms. Colour Bar Generator With functions: BAR/DOT/SQUARE/SYSTEM

Power Supply

AC/DC Voltmeter High sensitive (better use digital voltmeter) Isolation Transformer

Probe Low-capacitance / High impedance.

Mohm, below 10PF.

SELECT/VIDEO OUTPUT TERMINAL/CROSS-

HATCH/S-VIDEO OUTPUT TERMINAL functions and

green or red purity signal.

Source such as a battery or a well regulated and isolated DC bias supply. (Adjust 0-20V)

Voltage adjustable type having capacity of more than 200 watts.

FM/AM Signal Generator National ; MODEL : VP8177A

B+ VOLTAGE ADJUSTMENT Notice: (A) B+ voltage closely relates to the picture tube's positive high voltage.

(B) To prevent it from producing excessive hazardous X- RAY RADIATION, ensure that B+ voltage must be adjusted to at the 125V (CE-6401/6418/6409/7405)/ 124V(or)140V (CE-7406)/ 145V (CE-8608)/ 115V (CE-8616) POSITIONS.

1. Check the AC line voltage supplied is AC220V +-5% 50 Hz.

2. Turn in an active channel, adjust BRIGHTNESS and CONTRAST controls to obtain a normal picture.

3. Connect test point (C523) on the MAIN CHASSIS PCB with high impedance DC voltmeter.

4. Adjust VR501 (on the MAIN PCB) for B+ 125V +/-0.3V (CE-6401/6418/6409/7405)/ 124V(or)140V +/-

0.3V(CE-7406)/ 145V +/-0.3V(CE-8608)/ 115V +/-0.3V(CE-8616) voltage reading.

HIGH VOLTAGE CHECK:

CAUTION : There is no HIGH VOLTAGE ADJUSTMENT on this chassis. a. Connect an accurate high voltage meter to the second anode of the picture tube. b. Turn on the receiver and set the BRIGHTNESS, COLOUR and CONTRAST Controls to the minimum

(zero beam current).

c. High voltage will be measured below 35KV. d. Adjust the BRIGHTNESS Control to both extremes to ensure the high voltage does not exceed the limit of 34Kv under any circumstances.

FS CIRCUIT CHECK:

a. Push the Power Switch on and adjust all controls for normal operation. b. Temporarily connect a 18Kohm resistor across R908 on the Main Chassis PC Board. Raster and sound

will disappear.

c. The receiver must remain in this state even after removing the resistor. This is the evidence that the

Fail Safe circuit is functioning properly.

d. To obtain a picture again, temporarily push the power switch off and allow the Fail Safe circuit move

than 30 seconds to reset. Then push the power switch on to produce a normal.

FOCUS ALIGNMENT :

Tune in an active channel or Phillips Pattern. Adjust the Focus control on the FLYBACK TRANSFORMER (T902) for well defined scanning lines in the center area on the screen.

SCREEN VOLTAGE (VG2) ADJUSTMENT

Apply a FULL BLACK signal with a colour bar signal generator. Connect oscilloscope to measure pin of R132, R133 or R134 (Vbcmp) on the main board. Vbcmp means DC-level of the black current measurement pulse. Turn the CONTRAST and BRIGHTNESS controls to normal positions. Turn the SCREEN VR anti-clockwise to get the minimum value. Then turn the SCREEN VR clockwise slowly to get the reading of the DC-level at the RGB-output is 3.3V.

ATTN.: CE-7407 of SCREEN VOLTAGE adjustment reading of the DC-level at the RGB-output is 3.3V or

Screen Voltage is about DC 400V.

HORIZONTAL POSITION ADJUSTMENT

a. Receive the Phillips Pattern. Apply a crosshatch signal. b. Set the contrast and colour to their minimum, and the brightness to its maximum. c. Adjust (H-SHIFT) to move the picture at the center.

ATTN.: These settings should be done with separate test signals with a 50 Hz and a 60 Hz field frequency. These

parameters are stored in separate groups for 50 Hz and 60 Hz and are recalled or set, depending on the field frequency of the currently received program.

VERTICAL ADJUSTMENT

Apply a crosshatch signal. Adjust (V-SLOPE) to obtain half picture. Adjust (V-S.CORR) to obtain a linear picture. Adjust (V-SHIFT) to move the picture at the center. Adjust (V-AMPL) to obtain rightful high picture.

ATTN.: These settings should be done with separate test signals with a 50 Hz and a 60 Hz field frequency. These

parameters are stored in separate groups for 50 Hz and 60 Hz and are recalled or set, depending on the field frequency of the currently received program.

PICTURE WIDTH AND PINCUSHION DISTORTION ADJUSTMENT :

a. Perform this adjustment after the B+ volts and the Hor. CENTER adjustment are completed. b. Receive a Phillips Pattern. c. Set the contrast and colour to the minimum, and the brightness to the maximum. d. Adjust the H. WIDTH Control (VRC2) for the horizontal width so that the white flags on the left and

right of the pattern just hide. e. Adjust the DPC Control (VRC1) to correct the vertical line on left and right straight. f. Readjust the WIDTH Control (VRC2) for the precision.

DELAY AGC ADJUSTMENT :

Apply a 60dbu level with standard colour bar signal to the antenna input. Connect the probes of the high impedance DC voltmeter to C156. Adjust (AGC-ADJ) to get the reading of 4 - 5V till obtaining a clear picture.

CRT GREY SCALE ADJUSTMENT (WHITE BALANCE ADJUSTMENT):

Apply a white balance alignment signal with the white balance checker. Adjust brightness and contrast suitable for the adjustment. Adjust (R-GAIN), (G-GAIN) and (B-GAIN) to obtain a 9300 K colour temperature.

SAFETY PRECAUTION :

Dielectric voltage withstand test : The following accessible parts should be stressed for a period of one second on each complete appliance before it leaves the factory. The test potential voltage not less than 3500V, 50Hz should be applied for 1 second between both blades of the attachment plug cap. and the following parts :

Name of part Locations

1. Antenna Terminal Back Cabinet

2. AV input Terminals Front / Back Cabinet

3. AV output Terminals Back Cabinet

3. Enclosure Screws Back Cabinet

4. S-Video Sockets Front Cabinet

5. Ext. Speaker Terminals Back Cabinet

SOUND IF ALIGNMENT (BG-38.9MHz)

a. Apply IF signal (38.9 MHz, 10mV) to Pin 1 of D socket. b. Set a signal generator to colour bar and dual transmission with internal modulation of 3 KHz on channel

1 and 1 KHz on channel 2. c. Connect oscilloscope to pin 15 of ICF1 (TDA3857). d. Align the 38.9MHz coil (LF4) for minimum picture contents.

STEREO SOUND AND DUAL SIF ALIGNMENT (BG - 5.5MHZ, DK - 6.5 MHz)

a. Set transmitter to dual sound mode and off the main sound modulation. b. Adjust (LF5) 5.74MHz tank coil to minimum THD. c. Set transmitter to BG mono sound mode, connect the dual vertical input of the oscilloscope to RF17

(MAIN SOUND) 5.5MHz and RF15 (SUB SOUND) 5.74MHz. d. Adjust (LF6) 5.5MHz tank coil to minimum THD. e. Change the sound to D/K system, adjust (LF7) 6.5MHz tank coil to minimum THD. f. Re-align LF6 and LF7 to minimum THD both.

GERMAN STEREO FILTER COIL (LF8)

a. Set a signal generator to colour bar, stereo sound mode and off the main sound modulation (5.5 MHz

signal).

b. Connect the oscilloscope to Pin 5 of ICF2. c. Adjust FILTER COIL (LF8) for the maximum reading on the oscilloscope (envelope waveform) with

the minimum distortion.

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