Sanyo CE25DN4-C Schematic

Colour Television Service Manual

Model CE25DN4-C

Service Ref.No.: CE25DN4-C-01

PRODUCT CODE: 111339716 ORIGINAL VERSION: Chassis No. EB4-A(MKII)

CE25DN4-C

Give complete "SERVICE REF.NO." for parts order or servicing, it is shown on the rating sheet on the cabinet back of the TV set.

Note This TV receiver will not work properly in foreign countries where the television transmission system and power source differ from the design specifications. Refer to the specifications for the design specifications

Contents

Safety precautions/Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Circuit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5

Cabinet Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Service control adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Circuit alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Important notice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Special Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Cabinet Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Electric Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-19

Part No. SKSM0309 F7VVV APRIL 1999

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SAFETY PRECAUTION

X-RADIATION PRECAUTION

The primary source of X-RADIATION in the television receiver is the picture tube. The picture tube is specially constructed to limit X-RADIATION emissions. For continued X-RADIATION protection, the replacement tube must be the same type as the original including suffix letter. Excessive high voltage may produce potentially hazardous X-RADIATION. To avoid such hazards, the high voltage must be maintained within specified limit. Refer to this service manual, high voltage adjustment for specific high voltage limit. If high voltage exceeds specified limits, take necessary corrective action. Carefully follow the instructions for +B1 volt power supply adjustment, and high voltage adjustment to maintain the high voltage within the specified limits.

PRODUCT SAFETY NOTICE

PRODUCT SPECIFICATIONS

Product safety should be considered when a component replacement is made in any area of a receiver. Components indicated by mark in the parts list and the schematic diagram designate components in which safety can be of special significance. It is particularly recommended that only parts designated on the parts list in this manual be used for component replacement designated by mark . No deviations from resistance wattage or voltage ratings may be made for replacement items designated by mark .

!!!

1: An isolation transformer should be connected in the

power line between the receiver and the AC line when a service is performed on the primary of the converter transformer of the set.

2: Comply with all caution and safety-related notes

provided on the cabinet back, inside the cabinet, on the chassis or the picture tube.

3: When replacing a chassis in the cabinet, always be

certain that all the protective devices are installed properly, such as, control knobs, adjustment covers or shields, barriers, isolation resistor-capacitor networks etc.Before returning any television to the customer, the service technician must be sure that it is completely safe to operate without danger of electrical shock.

Power source AC 220~240V, 50Hz Television system System B/G, D/K Colour system PAL/NTSC 4.43/SECAM Receiving channel VHF: E2~E12, R1~R12

CATV: X, Y, Z, S1~S41

UHF: #21~69 Aerial input impedance 75 ohm AV terminal

21 Pin socket AV1: CENELEC standard (RGB/S-Video inputs)

AV2: CENELEC standard

AV2: RCA Terminal, video and audio (L/R) inputs Sound output(Music) 12 watts x 2 Picture tube 63cm diagonal, 110 degree (Visible picture diagonal) 59cm Dimensions (WxHxD) 680 x 543 x 442mm Weight 26.6 Kg

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BLOCK DIAGRAM

This is a diagram for all models and therefore differs slightly from the actual block diagram.

IC801

CPU

21P Scart: AV1

21P Scart: AV2

IC201

IF/Video/Chroma/Def.

IC1202

CVBS int/ext sw.

IC1201

CVBS AV2 sw.

CRT Unit

FBT

IC001

Audio Output

IC501

Vert. Output

T611

Converter Transformer

Power Supply Circuit

SIF Unit

Audio Unit

Tuner

IC802

Memory

SCL

SDA

RC Pre.amp

IC810

Band sw.

234

2: Bright 3: Contranst

4: Colour 5: Sharpness

Control Keys

45/46

28/29

30/31

X131

SAW Filter

IC271

1H Delay

R-Y/B-Y

CVBS In

Functuin In(AV1/AV2)

11/12

14/16

BLK

External CVBS in

Internal CVBS in

Q151 Q152/Q154

H-Drive

Q431

Q432

H-Outpit

V-Drive

V-Feedback

Audio In

Speakers

VR501

C512

Q2601

Q2611

Q2621

Video In

Audio In

L R

Q171

8 Out

4 Out

Audio I/O

Audio I/OVideo I/O

Video I/O

RGB/BLK In

B1: 150V

B2: 25V

B3: 15V

B4: 24V

IC651

IC652

B6: 12V

B8: 5V

L, R

1/ 5

10/ 8

AC In

Q612

Q613

V-In

CVBS In

AV1 I/O

SIF In

Audio Out L, R

IC653

B6: 12V

B7: 8V

3D Surround

Decoder

Nicam & Stereo

Decoder

AV2 I/O Front In

Audio

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1. POWER SUPPLY

The power supply circuit of the EB4-A chassis is composed of a rectifier smoothing circuit, an oscillation circuit, a control circuit and an output rectifier circuit. The AC input voltage is full-wave rectified by the rectifier smoothing circuit, and an unstable DC voltage is generated at both terminals of the smoothing capacitor C607. This voltage is input to the oscillation circuit. The oscillation circuit is provided with a blocking oscillator circuit that switches the switching transistor Q613 ON and OFF, and an oscillation frequency and a duty square wave pulse are generated in the input windings according to operation of the control circuit. A squarewave pulse whose size is dependent on the turn ratio of the input and output windings is obtained in the output winding. This is rectified in the output rectifier circuit, and the desired DC voltage is obtained.

2. IF & DEFLECTION (TDA8361)

The IF output signal from the tuner passes through the SAW filter, and it is input to pin45 and pin46 of IC201. The signal input to the IC passes through the IF amplifier, video detection and video amplifier circuits and is output from pin7 as a composite video signal. And after this signal is converted to impedance at Q151, supplies to the video and chroma amplifier stages. The sync.-separation circuit separates the video signals applied to pin13(internal video signal) or pin15(external video signal) to vertical- and horizontal-sync. signals respectively. The horizontal oscillator requires no external components and is fully integrated. The oscillator is always running when the start-pin36 is supplied with 8V. Horizontal drive signal is output from pin37. VR361 is for adjustment of the horizontal centring. The separated vertical-sync. signal from sync. separation circuit passes through the vertical-separation circuit, and applied to trigger divider circuit. The horizontal oscillation pulse and input vertical sync. pulse are monitored by the trigger divider circuit, and switching 50Hz and 60Hz system, the vertical amplitude automatically adjusted for 50Hz and 60Hz. The output signal from the trigger divider is triggered vertical oscillation circuit consisting of C351, R352 and pin42, and vertical drive pulse is output from pin43. VR501 is for changing the amount of AC feedback applied to pin41 and for adjustment of the vertical amplitude.

3. VIDEO CHROMA & R.G.B. (TDA8361)

The composite video signal output from the pin7 of IC101 passes through Q151-Q154, and it is supplied to pin13. The external video signal output from SCART is supplied to pin15. The video signal input to pin13 or pin15 is separated to luminance (Y) signal and chroma signal in IC201. These pins are used in common with H/V-sync. separation input. The peaking of Y signal is adjusted by DC voltage of pin14. (“SHARPNESS” control) The chroma signal is divided into R-Y and B-Y

chroma signals, demodulated in IC201, and output from pin30 (R-Y) and pin31 (B-Y). These chroma signals pass through the 1H delay line circuit (IC271), and they are input to pin29 (R-Y) and pin28 (B-Y). These R-Y/B-Y signals pass through RGB matrix circuit and RGB selector circuit of IC101. The internal RGB signals are generated in RGB matrix circuit and the RGB selector, consisting linear amplifiers, clamps and selects either the internal RGB signals or the external RGB signals input from pin22(R), pin23(G), pin24(B). Selection is controlled by the voltage at the RGB switch control (pin21) and mixed RGB modes are possible since RGB switching is fast. The RGB switch also functions as a fast blanking pin by blanking the RGB output stages; here internal and external RGB signals are overruled. The colour gain is controlled by DC voltage of pin26. (“COLOUR” control) The contrast control voltage present at pin25, and the brightness control voltage present at pin17 controls DC level of RGB signals. The RGB signals are finally buffered before being available at the RGB output pins [pin20 (R), pin19 (G), pin18 (R)].

4. AUDIO OUTPUT(TDA7263M)

The audio signals output from the audio unit are input to pin1(L) and 5(R) of IC171 and passes through the preamplifier circuit and drive circuit, after which it is input to the audio amplifier. The audio amplifier is an SEPP (single-ended, push-pull) OTL type and output to pin8(R) and 10(L) to directly drive the speakers.

5. VERTICAL OUTPUT (LA7832/LA7832)

An IC (LA7832/LA7833) is used for the vertical output circuit in this chassis. The vertical drive pulse from pin43 of IC201 is input to pin4 of IC501. This pulse drives IC501, and vertical scanning is performed. In the first half of scanning a deflecting current is output from pin2 and passes through the following path: Vcc(B4) ➞ D501 ➞ pin3 ➞ pin2 ➞ DY ➞ C512 ➞

VR501/R509. An electric charge is then stored in C512. In the last half of scanning the current path is C512 ➞

DY ➞ pin2 ➞ pin1 ➞ VR501/R509 ➞ C512. In this way, an amplifying sawtooth waveform current flows directly to

DY to perform electron beam defection. Next, in the first half of the banking period the vertical drive pulse suddenly becomes OFF, and in order to reduce the current flowing to DY, the current path becomes as follows by the inductance of DY: DY ➞ pin2 ➞ pin1 ➞ VR501/R509 ➞ C512 ➞ DY. Also,

when the charge of DY has dissipated, the current path becomes Vcc24V ➞ pin6 ➞ pin7 ➞ C502 ➞ pin3 ➞

pin2➞ DY ➞ C512 ➞ VR501/R509, and when the prescribed current value is reached, the vertical drive

pulse becomes ON. This completes one cycle.

CIRCUIT DESCRIPTION

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F7VVV

6. HORIZONTAL OUTPUT

A horizontal oscillation signal is output from pin37 of IC201 and switches the drive transistor Q431. This switching signal is current amplified by the drive transformer T431 and drives the output transistor Q432. When Q432 becomes ON, an amplifying current flows directly to DY through C441 ➞ DY ➞ 0432 ➞ GND, and

defection is performed in the last half of the scanning period. Next, when Q432 becomes OFF, the charge that had been stored in DY up to that point releases a resonance current to the resonant capacitors C421/C423 and charges them. The current stored in C421/C423 is then flowed back to DY, and an opposite charge is then stored in DY. This opposite charge then switches the dumper diode in Q432 ON, the resonance state is completed, and an amplifying current is then flowed again directly to DY through the dumper diode. By this means, deflection in the first half of the scanning period is performed, and when Q432 becomes ON at the end of the first half of the scanning period, deflection during the last half is begun, thus completing one cycle.

In the PCC circuit consisting of Q461 and Q462, the parabola signal supplied from the vertical circuit is added at the horizontal output stage and pincushion compensation is performed by varying the DC voltage bias. Further, the ABL voltage is feedback to the base of Q462 to compensate for width variations due to variations in the beam current.

7. CPU <System and Teletext Control> Pin description Pin1: Tuning voltage output Pin2: Brightness control output (6-bit DAC) Pin3: Contrast control output (6-bit DAC) Pin4: Colour control output (6-bit DAC) Pin5: Sharpness control output(6-bit DAC) Pin6: Not used (GND) Pin7: Not used (GND) Pin8: Power ON/OFF output (H:ON) Pin9: AFT signal input Pin10: Option SW1 & Keyboard scan input (DC) Pin11: Option SW2 Pin12: 50/60Hz switch input (50Hz: Hi) Pin13: GND Pin14: TV/AV switch output (TV: Hi) Pin15: S-VHS switch output (S-VHS: Hi) Pin16: Option SW3 (2AV: Hi) Pin17: Function signal input for SCART1 Pin18: Function signal input for SCART2 Pin19: Power LED drive output1 Pin20: Option SW4 & Power LED drive output2 Pin21: Ignore output Pin22: GND Pin23: CVBS input0 (Internal) Pin24: CVBS input1 (Internal/External) Pin25: Black

Pin26: IREF Pin27: Odd/Even output Pin28: GND Pin29: Pin30: V-deflection stop output Pin31: RGB REF Pin32: Blue output for OSD Pin33: Green output for OSD Pin34: Red output for OSD Pin35: Blanking output for OSD Pin36: H-sync. input (Horizontal pulse for OSD) Pin37: V-sync. input (Vertical pulse for OSD) Pin38~39: Supply (+5V) Pin40: OSC GND Pin41: Oscillator input for CPU Pin42: Oscillator output for CPU Pin43: Reset input Pin44: Supply (+5V) Pin45: Protect signal input (L:Power circuit defects) Pin46: Ident. signal input Pin47: R/C signal input Pin48: Mute output in no picture Pin49: I2C bus SCL (Serial clock) Pin50: I2C bus SDA (Serial date) Pin51: Option SW5 & Band select output1 Pin52: Band select output2

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CABINET DISASSEMBLY

CABINET BACK DISASSEMBLY

1. Remove 10 screws(A).

2. Pull out the cabinet back.

PLACING THE CHASSIS TO SERVICE POSITION

1. Pullout the chassis and put it to the rails on the side cabinet.

2. Fix main board with hook on the top rail.

(A)

B1 POWER SUPPLY ADJUSTMENT

1. Set VR641 to be mechanical centre before pressing the main switch.

2. Tune the receiver to PAL circular pattern.

3. Set brightness and contrast controls to normal.

4. Connect digital V-meter to test point "TP-B".

5. By using VR641, adjust voltage to 150 ± 0.5 V.

AFT ADJUSTMENT

1. Tune the receiver to the clearest station.

2. By using T141, adjust AFT to obtain the best picture.

AGC ADJUSTMENT NOTE:

Do not attempt this adjustment with weak signal.

1. Tune the receiver to the clearest station.

2. Set AGC VR(VR131) in direction which causes snow

noise to appear, then in the opposite direction until snow noise just disappears.

GREY SCALE ADJUSTMENT [SCREEN VR ADJUSTMENT]

1. Tune the receiver to the white pattern.

2. Set brightness and contrast controls to normal.

3. Set VR602and VR612 to be mechanical centre.

4. Turn VR601, VR611 and VR621 fully counter-

clockwise.

5. Set mode to one horizontal scanning line, how to set refer to "service mode"

6. Set screen VR for one colour to be just visible.

[BIAS VR ADJUSTMENT]

7. By using VR601, VR611 or VR621, adjust line to be

white.

8. Set screen mode OFF, how to set refer to "service mode"

[DRIVE VR ADJUSTMENT]

9. By using VR602 and VR612, adjust white balance.

HIGH VOLTAGE & WIDTH ADJUSTMENT [HIGH VOLTAGE ADJUSTMENT]

1. Tune the receiver to circular pattern.

2. Set brightness and contrast controls to maximum.

3. Connect digital V-meter to both terminals of R224, and high voltage meter to CRT anode.

4. Confirm high voltage to be 26.0 ± 1 KV at beam current 1.3, and less than 29.0 KV at 0 beam current.

[H-WIDTH ADJUSTMENT]

5. Adjust VR462 to obtain proper H- width.

6. Reconfirm high voltage.

H-CENTRE ADJUSTMENT

1. Tune the receiver to circular pattern.

2. Adjust H-centre by using VR361.

V-CENTRE ADJUSTMENT

1. Tune the receiver to circular pattern.

2. Adjust V-centre by using SW501.

V-SIZE ADJUSTMENT

1. Tune the receiver to circular pattern.

2. Adjust V-size by using VR501.

FOCUS ADJUSTMENT

By using FOCUS VR, adjust focus control for good scanning lines.

SERVICE CONTROL ADJUSTMENT

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F7VVV

SW601

Main switch

F601

Fuse

T481

RC Transformer

SW1901 Prog.+

SW1902 Prog.-

SW1903 Vol.+

SW1904 Vol.-

Q641

VR641

+B ADJ.

Q681

IC801 CPU

Q501

Q432

H-Output

IC501

V-Outout

IC651

+12V

Scart 2

SW501

V-Centre

VR501

V-Size

IC271

1H Delay

IC652

+8V

Scart 1

IC201 IF/Video/Croma/Def.

IC281

VR361

H-Centre

VR131

AGC

T101

T141

SIF Board

A101 Tuner

IC1202

Int./Ext. SW.

IC1201

AV2 SW.

TP-E

TP-

Q-SOUND Board

T611

Converter Trans

TP-B

VR462

H-Width

Q461

Q462

T451

Flyback

Transformer

R224

J213

Q501

Q432

H-Output

IC501

V-Outout

Scart 2

SW501

V-Centre

VR501

V-Size

IC271

1H Delay

Scart 1

IC201 IF/Video/Croma/Def.

IC281

VR361

H-Centre

VR131

AGC

T101

SIF Board

A101 Tuner

IC1202

Int./Ext. SW.

IC1201

AV2 SW.

TP-E

Q-SOUND Board

T141

VR641

VR642

VR361VR501SW501

VR131

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F7VVV

DC 15.5V AGC voltage (4.3-4.5V) Output probe

Input probe Marker frequency Sweep ATT

0dB=176mVrms/75

SETTING

C644 + IC201-pin48 IC201-pin45 (Side b) IC201-pin7

38.9MHz 20dB

Adjustment

By using T141, adjust "P" to be maximum amplitude.

Waveform

CIRCUIT ALIGNMENT

VIF alignment

0.002µF

75Ω

1kΩ

a b

10kΩ

Input probe

Output probe

SIF alignment

SIF BOARD

DC 12V AGC voltage(5V DC) Output probe

Input probe Sweep ATT Marker Frequency Tool-A

SETTING

IC3801-pin9 IC3801-pin13 IC3801-pin5 (Side b) IC3801-pin17 10dB

38.9MHz IC3801-pin6 and ground

Adjustment

1. By using T3801, adjust the VCO oscillation to be "P".

Waveform

0.01

Tool-A

IC3811

IC3801

K38H2

K38H1

T3801

+ 16 hidden pages