Sanyo CE26SN3-C Schematic

Colour Television

Service Manual

CE28SN3-C

Model CE28SN3-C

Service Ref.No.: CE28SN3-C-12

PRODUCT CODE: 111328207

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

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
Electrical Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	12-20

Part No. SKSM0280 F2ZHY

November 1999

SAFETY PRECAUTION

1: An isolation transformer should be connected in the	3: When replacing a chassis in the cabinet, always be
power line between the receiver and the AC line	certain that all the protective devices are installed
when a service is performed on the primary of the	properly, such as, control knobs, adjustment covers
converter transformer of the set.	or shields, barriers, isolation resistor-capacitor
	networks etc.Before returning any television to the
2: Comply with all caution and safety-related notes	customer, the service technician must be sure that it
provided on the cabinet back, inside the cabinet, on	is completely safe to operate without danger of
the chassis or the picture tube.	electrical shock.

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 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 ! .

PRODUCT SPECIFICATIONS
Power source	AC 220~240V, 50Hz
Television system	System B/G
Colour system	PAL/NTSC 4.43
Receiving channel	VHF: E2-E12
	CATV: X, Y, Z, S1-S41
	UHF: #21~69
Aerial input impedance	75 ohm
AV terminal
21 Pin socket	AV1: CENELEC standard (with RGB/S-inputs)
	AV2: CENELEC standard
	AV2: RCA Terminal, Video anf Audio (L/R) input
Sound output (Music)	12 watts x 2
Picture tube	70cm diagonal, 110 degree
(Visible picture diagonal)	66cm
Dimensions (WxHxD)	628 x 567 x 469mm
Weight	30.4 Kg

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EB4 MKII chassis

-3-

chassis MKII EB4

IC801

RC Pre.amp

CPU

47

10

Control Keys

2

3

2: Bright 3: Contranst

6

SCL

49

4

4: Colour 5: Sharpness

5

SDA

5

50

17

Functuin In(AV1/AV2)

18

IC802

Memory IC810

24

CVBS In

Band sw.

VL

51

VH

52

1

14

16

Audio

U

X131

TU

SAW Filter

45/46

IF

Tuner

InSIF

InFront

I/OAV2

I/OAV1

IC271

1H Delay

R-Y/B-Y

28/29

11/12

R-Y/B-Y

14/16

30/31

SIF

Audio

3D Surround

Unit

Unit

Decoder

Nicam & Stereo

Decoder

B6: 12V

Power Supply Circuit

Audio Out L, R

T611

Converter Transformer

B8: 5V

IC653

B7: 8V	B6: 12V
AC In

Q612	Q613	IC652	IC651

B1: 150V

B2: 25V

B3: 15V

B4: 24V

21P Scart: AV1				21P Scart: AV2	Audio In	Video In
					L R
Audio I/O		Video I/O	Video I/O Audio I/O
				V-In
		V-In		6	7	2
				3	4 Out
		RGB/BLK		1 8 Out
				IC1202	IC1201
			Q171		CVBS AV2 sw.
	B			CVBS int/ext sw.
24
		In
	G
23
	R
22
BLK
21	External CVBS in
15
13	Internal CVBS in				CRT Unit
	Q151		Q152/Q154
7				Q2601
CVBS In
				Q2611
R
20				Q2621		HV
G

19

B

18 Q432

H-Outpit

Q431

H-Drive

37

41 48 IC201 IF/Video/Chroma/Def.

FBT

IC501

Vert. Output

V-Drive

4

2

H

V-Feedback

V

IC001
Audio Output			C512
Audio In			DY
1/ 5	10/ 8	Speakers	VR501
L, R
		L, R

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

CIRCUIT DESCRIPTION

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 verticaland 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.

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EB4 MKII chassis

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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EB4 MKII chassis

CABINET DISASSEMBLY

CABINET BACK DISASSEMBLY

1.Remove 10 screws(A).

2.Pull out the cabinet back.

						(A)
(A)			(A)

(A)	(A)

(A)

(A)

(A) (A)

(A)

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.

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EB4 MKII chassis