DAEWOO DVT14F4P, DVT20F4, DVT20F4FA, DVT20F4LA, DVT20F4PA Service manual & schematics

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Page 1

SAFETY INSTRUCTIONS

WARNING: BEFORE SERVICING THIS CHASSIS, READ THE "X-RAY RADIATION PRECAUTION", "SAFETY PRECAUTION" AND "PRODUCT SAFETY NOTICE" BELOW.

X-RAY RADIATION PRECAUTION

Excessive high voltage can produce potentially hazardous X-RAY RADIATION.To avoid such hazards, the high voltage must not exceed the specified limit. The nominal value of the high voltage of this receiver is 25.5 kV (21":26.5 kV) at max beam current. The high voltage must not, under any circumstances, exceed 27.5 kV (21":29.0 kV).

Each time a receiver requires servcing, the high voltage should be checked following the HIGH

VOLTAGE CHECK procedure on page 9 of this manual. It is recommended the reading of the high voltage be recorded as a part of the service records, It is important to use an accurate and reliable high voltage meter.

2. The only source of X-RAY Radiation in this TV receiver is the picture tube.For continued X-RAY RADIATION protection,the replacement tube must be exactly the same type tube as specified in the parts list.

■ SAFETY PRECAUTION

1. Potentials of high voltage are present when this receiver is operating. Operation of the receiver outside the cabinet or with the back board removed involves a shock hazard from the receiver.
- 1) Servicing should not be attempted by anyone who is not thoroughly familiar with the precautions necessary when working on highvoltage equipment.
2) Always discharge the picture tube before handling the tube. The picture tube is highly evacuated and if broken, glass fragments will be violently expelled.
2. If any Fuse in this TV receiver is blown, replace it with the FUSE specified in the Replacement Parts List.
3. When replacing a high wattage resistor(oxide metal film resistor)in circuit board, keep the resistor 10mm away from circut board.
4. Keep wires away from high voltage or high temperature components.
5. This receiver must operate under AC230 volts, 50Hz. NEVER connect to DC supply or any other power or frequency.

PRODUCT SAFETY NOTICE

Many electrical and mechanical parts in this have special safety-related characteristics. These characteristics are often passed unnoticed by a visual inspection and the X-RAY RADIATION protection afforded by them cannot necessarily be obtained by using replacement components rated for higher voltage,wattage,etc. Replacement parts which have these special safety characteristics are identified in this manual and its supplements, electrical components having such features are

identified by designated symbol on the parts list. Before replacing any of these components, read the parts list in this manual carefully. The use of substitute replacement parts which do not have the same safety characteristics as specified in the parts list may create X-RAY Radiation.

Page 2

MAIN BOARD VIEW

Page 3

■ INSTALLATION & SERVICE ADJUSTMENTS

GENERAL INFORMATION

All adjustments 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. But, several minor adjustments may be required depending on the particular location in which the receiver is operated. This receiver is shipped completely in a card-board carton. Carefully draw out the receiver from the carton and remove all packing materials.

Plug the power cord into an AC power outlet. Turn the receiver ON and adjust the FINE TUNING for the best picture detail. Check and adjust all the customer controls such as BRIGHTNESS, CONTRAST and COLOUR Controls to obtain a natural B/W picture.

PROTECTION CIRCUIT CHECK

1. Turn on the receiver.
2. The receiver must be turned off and changed to stand-by mode.

HIGH VOLTAGE CHECK

1. Connect an accurate high voltage metre to the anode of the picture tube.
2. Turn on the receiver. Set the BRIGHTNESS and CONTRAST controls to minimum(zero beam current).
3. High voltage should be below 27.5 $\mathbf{kV}$ (21":29.5 $\mathbf{kV}$ )

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 of the receiver is switched ON.If the set is moved or placed in a different direction, the power switch must be switched off for at least 15 minutes in order to make the automatic degaussing circuit operate 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 the AC source.

If colour shading still persists, perform the COLOUR PURITY ADJUSTMENT and CONVERGENCE ADJUSTMENTS procedures, as mentioned later.

DYNAMIC CONVERGENCE ADJUSTMENT

Dynamic convergence (convergence of the three colour field at the edges of the CRT screen) is accomplished by proper insertion and positioning of three rubber wedges between the edges of the deflection yoke and the funnel of the CRT. This is accomplished as follows:

1. Switch the receiver on allow it to warm up for 15 minutes.
2. Apply crosshatch pattern from dot/bar generator to the receiver. Observe spacing between lines around edges of the CRT screen.
3. Tilt the deflection yoke up and down, and insert tilt adjustment wedges 1 and 2 between the deflection yoke and the CRT until the misconvergence illustrated in figure. 2(A) has been corrected.
4. Tilt the deflection yoke right and left, and insert tilt adjustment wedge 3 between the deflection yoke and the CRT until mis-convergence illustrated in figure. 2(B) has been corrected.
5. Alternately change spacing between, and depth of the insertion of, the three wedges until proper dynamic convergence is obtained.
6. Use a strong adhesive tape to firmly secure latch of the three rubber wedges to the funnel of the CRT.
7. Check purity and readjust, if necessary.

STATIC (CENTRE) CONVERGENCE ADJUSTMENT

1. Switch the receiver on and allow it to warm up for 15 minutes.

2. Connect the output of a crosshatch generator to the receiver and concentrating on the centre of the CRT screen, proceed as follows:

a. Locate the pair of 4 pole magnet rings. Rotate individual rings (Change spacing between tabs)to converge the vertical red and blue lines.Rotate the pair of rings (maintaing spacing between tabs)to converge the horizontal red and blue lines. (Refer to fig. 1 (A))

b. After completing red and blue centre convergence, locate the pair of 6 pole magnet rings. Rotage individual rings (change spacing between tabs) to converge the vertical red and blue (Magenta)and green lines. Rotate the pair of rings (maintaining spacing between tabs)to converge the horizontal red and blue(Magenta) and green lines.(Refer to Fig. 1(B))

Page 4

COLOR PURITY ADJUSTMENT

For the best result, it is recommended that the purity adjustment is made in final receiver location. If the receiver will be moved, perform adjustment with it facing east. The receiver must have been operating 15 minutes prior to this procedure and the faceplate of the CRT must be at room temperature. The receiver is equipped with an automatic degaussing circuit. But, if the CRT shadow mask has become excessively magnetized, it may be necessary to degauss it with manual coil. Do not switch the coil.

The following procedure is recommended while using a dot generation.

1. Check for correct location of all neck components (See figure. 5).
2. Rough-in the static convergence at the centre of the CRT, as explained in the static convergence procedure.
3. Rotate the picture control to centre of its rotation range, and rotate brightness control to max. CW position.
4. Apply green color signal to produce a green raster.
5. Loosen the deflection yoke tilt adjustment wedges (3), loosen the deflection yoke clamp screw and push the deflection yoke as close as possible to the CRT screen.
6. Begin the following adjustment with the tabs on the round purity magnet rings set together, initially move the tabs on the round purity magnet rings to the side of the CRT neck. Then, slowly separate the two tabs while at the same time rotaing them to adjust for a uniform green vertical band at the CRT screen.
7. Carefully side the deflection yoke backward to achieve green purity. (uniform green screen) Centre purity was obtained by adjusting the tabs on the round purity magnet rings, outer edge purity was obtained by sliding the deflection yoke forward.
Tighten the deflection yoke clamp screw.
8. Check for red and blue field purity by applying red signal and touch up adjustments, if required.
9. Perform black and white tracking procedure.

SCREEN & WHITE BALANCE ADJUSTMENT

1. This adjustment is to be made only after warming up at least 15 minutes.
2. Receive RETMA pattern signal.
3. Set the RGB Bias VR (R522,R512,R502) to minimum.

4. Set the G,B Drive VR (R515,R505)to center.
5. Set the CONTRAST, BRIGHTNESS, COLOR control to MIN, and Sub-bright VR(R013)to CENTER.
6. Rotate the R, G and B Bias VR of the other color which did not appear on the screen clockwise, until a dim white is obtained.
7. Set the CONTRAST, BRIGHTNESS, COLOR control to MAX.
8. Set the G, B Drive VR to obtain the best white uniformity on the screen.
9. Rotate the CONTRAST, BRIGHTNESS, COLOR controls until a dim raster is obtained and touch-up adjustment of RGB Bias VR to obtain the best white uniformity on the screen.

SUB-BRIGHTNESS ADJUSTMENT

1. White balance adjustment must proceed this procedure.
2. Set the CONTRAST, BRIGHTNESS, COLOR control to MIN.
3. Rotate the SUB-BRIGHTNESS VR (R013) gradually CCW until the last beam disappears on the screen.

VERTICAL HEIGHT ADJUSTMENT

1. Receive RETMA pattern signal.
2. Set the BRIGHTNESS control and CONTRAST control to Max., and the COLOR control to centre.
3. Adjust R011 for the optimum vertical height and over scanning.

VERTICAL CENTER ADJUSTMENT

1. Receiver RETMA pattern signal.
2. Adjust R030 so that the vertical center of the picture may be coincident with the mechanical center of CRT.

HORIZONTAL CENTER ADJUSTMENT

1. Receive RETMA pattern signal.
2. Adjust R012 so that the horizontal center of the picture may be coincident with the mechanical center of CRT.

FOCUS VOLTAGE ADJUSTMENT

1. Receive RETMA pattern signal.
2. Adjust the FOCUS VOLUME on the FBT and make the picture on the screen be finest.

Page 5

RF AGC ADJUSTMENT(MAIN)

1. Receive PAL COLOR BAR signal in the VHF high band where the strength of signal can be 75dB.
2. Set the CONTRAST control to Max., the BRIGHTNESS control to provide adequate black and gray scales.
3. Connect an oscilloscope to P211.(Tuner AGC point)
4. Maintain the fine tuning on the screen, and adjust R010(AGC DELAY CONTROL VR.) to max.
5. Adjust the VR(R010) max to below 2.2V(FA/LA:2.2V).

MAIN B+(+103V) ADJUSTMENT

1. Set the picture level to service 1 mode.(Bright:31, Colour:31, Contrast:48, Sharpness:48)
2. Connect DC voltage meter to the P805 and adjust R080 for +103V DC.

RF AGC ADJUSTMENT(SUB)

1. Receive PAL COLOR BAR signal in the VHF high band where the strength of signal can be 75dB.
Set the CONTRAST control to Max., the BRIGHTNESS control to provide adequate black and gray scales.
3. Connect an oscilloscope to P211.(Tuner AGC point)
4. Maintain the fine tuning on the screen, and adjust R090(AGC DELAY CONTROL VR.) to max.
5. Adjust the VR(R090) max to below 2.2V(FA/LA:1.6V).

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Page 7

Page 8

CHASSIS : CP - 350

SCHEMATIC DIAGRAM

* PAL I
∗ PAL B/G
∗ PAL-B/G. SECAM-L/L'

RUN NO.3 NOVEMBER, 1996

NOTES :

1. THE UNITS OF RESISTANCE "OHM" IS DMITTED. (K−1000 OHMS M∞1000000 OHMS)
2. ALL RESISTORS ARE 1/4 WATT UNLESS OTHERWISE NOTED.
CAPACITANCE VALUES 1.0 AND ABOVE ARE IN pF THOSE BELOW ARE IN uF EXCEPT AS INDICATED. ( uF=1000000 pF)
4. INDUCTOR VALUES ARE IN UH EXCEPT AS INDICATED.
5. ALL DIODES ARE IN4148 EXCEPT AS INDICATED.
6. ALL NPN TRANSISTORS ARE KTC3198Y ALL PNP TRANSISTORS ARE KTA1286Y EXCEPT AS INDICATED.
7. DC VOLTAGE AND AC WAVEFORM MEASUREMENT CONDITIONS.
ALL THE VOLTAGES AT EACH POINT IS MEASURED UNDER THE STANDARD COLDUR BAR SIGNAL INPUT (5 CHANNEL) AND ALL CONTROLS SET TO THE MAXIMUM POSITION.
( DC VOLTAGES WITH VIVM AND AC WAVEFORMS WITH OSCILLOSCOPE )
(FOR A NOMINAL LINE VOLTAGE : AC 230V 50H2)
8. SINCE THIS SCHEMATIC DIAGRAM IS A STANDARD ONE THE CIRCUIT AND CIRCUIT CONSTANTS MAY BE SUBJECT TO CHANGE FOR IMPROVEMENT WITHOUT ANY NOTICE.

SAFETY CAUTION :

BEFORE SERVICING THIS CHASSIS IT IS IMPORTANT THAT THE SERVICE TECHNICIAN READ AND FOLLOW THE "X-RAY RADIATION PRECAUTION", "SAFETY PRECAUTIONS" AND "PRODUCT SAFETY NOTICE" IN THE SERVICE MANUAL.

PRODUCT SAFETY NOTE :

THE COMPONENTS INDICATED WITH SYMBOL ▲ ARE INPORTANT FOR MAINTAINING. THE SAFETY OF THE SET AND SHOULD BE REPLACED ONLY WITH TYPES IDENTICAL TO THOSE IN THE ORIGINAL OR SPECIFIED ONE IN THE PARTS LIST. DON'T DEGRADE THE SAFETY OF THE SET THROUGH IMPROPER SERVICING.

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DIFFERENT PART FOR SYSTEM ( ! )

PAL-B/G P-8/G REMARK SECAM-1/1 MAIN VIE -TDA9B30 FAL 2483/84 2163/84 J1951M ).4MH AGC SUB 0.22uF 100µF 0.6.5 1000pF 1S2186 4/ BB909A 4857621200 WIRE COPPER SECAM-L WIRE COPPER WIRE COPPER B/G SOUND POWER CORD CW-3222 CW-4232 ← KTC 3197 KTC3198Y KTA1286Y 0205 Q902 Q904 Q905 KTC3198Y KTC3198Y 89 70 KTC31987

NO.	SYSTEM	• •	D D (0)	PAL-B/G	REMARK
	LOC.	P - I	P-8/G	SECAM-L/L'	ALWARK
73	R091			10KB
74	R110			1/4 4.3K
75	R202			1/4 4.7K
76	R902			1/4 750
77	R905			1/4 4.7K
78	R906			1/4 22K
79	RC106			1/10 100
80	RC111			1/10 2.2K
81	RC112			1/10 10K
82	RC113			1/10 10K
83	RC114			1/10 10K
84	RC115			1/10 22K
85	RC118			1/10 68K
86	RC120			1/10 IK
87	RC123			1/10 1K
88	RC201			1/10 4.7K
89	RC202			1/10 4.7K
90	RC203			1/10 4.7K
91	RC2D4			1/10 22K
92	RC207			1/10 4.7K
93	RC208			1/10 22K
94	RC211			1/10 10K
95	RC212			1/10 4.7K
96	RC213			1/10 39K
97	RC299			1/10 22K
98	RC730			1/10 4.7K
99	RC7B2			1/10 10K
100	RC797	1/10 9.1K	_ ←	1/10 6.8K
101	RC901			1/10 4.7K
102	RC908			1/10 10K
103	RC909	•		1/10 68K
104	RC910			1/10 10K
10.5	RC911			1/10 22K	·
106	RC912			1/10 100
107	RC913			1/10 4.3K
108	RC914			1/10 4.7K
109	RC915		*	1/10 2.2K
110	RC916			1/10 7.5K	-
111	RC917	_		1/10 10K	-
112	RC918			1/10 100K	İ
113	RC920			1/10 100K
114	RC921			1/10 330
115	RC925			1/10 4.7K
116	RCP08	(1/10 1K)	-	-	VPS/PDC OPTION
117	RCP09		- \|		CLOCK OPTION
118	RCP17	1/10 16		←	TEXT(WEST) ON
119	RCP18		·	+ · ·	TEXT TURKISH
120	RCP19				TEXT FAST
121	RCP23	1/10 14	4		AV2 OPTION
122	8201	1/4 18	+ `	+ `	IL-BAND OPTION
123	8202	1/4 11	6		S VIEW OPTION
	RP03	1/8 1K	+ `	1/5.1%
124			1	1 1/9 14
124	RP04			1/4.1%	SVSTON OSP

DIFFERENT PART FOR SIZE ( ! )

			·
NO. LOC.	20*	21"
NO. LOC.	^0, LOC.	ORION	ORION	NSMONN
1	CRT	A48JLL90X02	A51JSW90X02
2	D/COIL	DC-2050	DC-2070
3	GROUND	48519A5110	48519A5310
4	T402	DCF-2217J	DCF-2217L	FBT
5	C407	1.6KV 7500P	1.6KV 8200P	MYLAR
6	C408	2KV 220pF	2KV 270pF
7	C409	200V 0.47uF	200V 0.33uF	MYLAR
8	R8D1	J503P54 D180M290	J503P53 D140M290L	POSISTOR
9	RC301	1/10 510K	1/10 220K
10	RC304	1/10 820	1/10 680
11	RC305	1/10 560	1/10 270

PEAKING
CHOKE	(c
BEAD	(B

CAPACITOR
ELECTRO '
CERAMIC
CERAMIC CH	— → ⊢ (CH)
TANTAL	;( (T)
ELECTRO NONPOLAR	(NP)
MYLAR	—ı⊢ (M)
CHIP CERA	cc