Daewoo DV-T7C1, ST-280K, DV-T7E1, DV-T7M1, ST-290K Service Manual

S/M No. : VT7C1PSEF0

Service Manual

Video Cassette Recorder

ALL T -MECHA (Hi-Fi/MONO)

Model: (PAL/SECAM MODELS)
D V-T7C1/4C1/2C1 Series
D V-T7E1/4E1/2E1 Series
D V-T7M1/4M1/2M1 Series
D V-T7J1/4J1/2J1 Series
D V-T7D1/4D1/2D1 Series
D V-T7T1/4T1/2T1 Series
D V-T7W1/4W1/2W1 Series
D V-T7L1/4L1/2L1 Series

DV -T7L1

DV-T7E1

DV-T7C1

DV-T7B1

D AEW OO ELECTR ONICS CO., LTD.

http : //svc.dwe .co.kr

Feb. 2001

TABLE OF CONTENTS

SAFETY&PRECAUTIONS................................................................................................ 2

EXTERNAL VIEWS......................................................................................................... 4

FRONT VIEWS FUNCTION.................................................................................................................... 4

REAR VIEWS FUNCTION...................................................................................................................... 6

ELECTRICAL ADJUSTMENT............................................................................................ 7

SPECIFICATIONS ......................................................................................................... 8

VOLTAGE CHART ........................................................................................................ 9

CIRCUIT DIAGRAM...................................................................................................... 13

POWER CIRCUIT DIAGRAM ................................................................................................................. 13

SYSCON CIRCUIT DIAGRAM............................................................................................................... 14

A/V CIRCUIT DIAGRAM (PAL)............................................................................................................... 15

A/V CIRCUIT DIAGRAM (SECAM)......................................................................................................... 16

PIF CIRCUIT DIAGRAM ........................................................................................................................ 17

HI-FI & SW CIRCUIT DIAGRAM............................................................................................................. 18

SW CIRCUIT DIAGRAM ....................................................................................................................... 19

SHUTTLE / PATH JIG DIAGRAM............................................................................................................. 20

WAVEFORMS ON VIDEO CIRCUIT ................................................................................ 21

COMPONENTS LOCATION GUIDE ON PCB BOTTOM VIEW ............................................ 24

PCB MAIN.......................................................................................................................................... 24

DISASSEMBLY ............................................................................................................. 25

PACKING ASS’Y ................................................................................................................................. 25

FRONT PANEL ASSEMBLY ................................................................................................................... 26

INSTRUMENT DISASSEMBLY ................................................................................................................. 30

ELECTRICAL PARTS LIST ............................................................................................... 3

PCB MAIN AS .................................................................................................................................... 31

TABLE OF DIFFERENT PART LIST FOR PCB MAIN AS .............................................................................. 43

APPENDIX (Appendix is provided only by internet http://svc.dwe.co.kr)

TROUBLE SHOOTING FLOW CHART .............................................................................. 1

POWER CIRCUIT................................................................................................................................. 1

PIF CIRCUIT........................................................................................................................................ 3

SERVO-SYSCON CIRCUIT.................................................................................................................... 4

AUDIO CIRCUIT (NORMAL) ................................................................................................................. 12

VIDEO CIRCUIT .................................................................................................................................. 15

µ

-COM PORT ............................................................................................................. 22

1

SERVICE MODE .......................................................................................................... 26

1

SAFETY & PRECAUTIONS

SAFETY CHECK AFTER SERVING

Examine the area surrounding the repaired location for damage or deterioration. Observe that screw, parts and wires
have been returned to original positions. Afterwards, perform the following tests and conform the specified values in order
to verify compliance whit safety standards.

1. Insulation resistance test
Confirm the specified insulation resistance between power cord plug prong and externally exposed parts of the set
(RF terminals, antenna terminals, video and audio input and output terminals, microphone jacks, earphone jacks, etc.)
isgreater than values given in table 1 below.

2. Dielectric strengthen test
Confirm specified dielectric strengthen between power cord
plug prongs and exposed accessible parts of the set
(RF terminals, antenna terminals, video and audio input output
terminals, microphone jack, ear phone jacks, etc.)
is greater than values given table 1.

3. Clearance distance
When replacing primary circuit component, confirm specified clearance distance (d), (d
and between terminals and surrounding metallic parts. See table below.

Rating for selected areas

AC Line Voltage Region

100V Japan

110 to 130V

* 110 to 130V

200 to 240V

* : Class model only

USA &

Latin America

Canada

Europe

Australia

Insulation

Resistance

$

1MΩ/500V DC

- 900V AC 1min.

$

10MΩ/500V DC 4kV AC 1min.

NOTE

This table is unofficial and for reference only. Be sure to confirm the precise values for your
particular country and locality

’

) between soldered terminals,

Dielectric

Strength

1kV

AC 1min.

Clearance

Distance(d),(d)

$

3

$

3.2

$

6(d)

$

8(d')

(a :Power cord)

✔

Caution

: In this Manual, some parts can be changed for improving, their
performance without notice in the parts list. So, if you need the
latest parts information,please refer to PPL(Parts Price List) in
Service Information Center (http://svc.dwe.co.kr).

2

4. Leakage current test
Confirm specified or lower leakage current between B(earth
ground, power cord plug prongs) and externally exposed accessi­ble parts (RF terminals, antenna terminals, video and audio input
output terminals, microphone jacks, earphone jacks, etc.)
Measuring method:(Power ON) Insert load Z between B(earth
ground, power cord plug prongs) and exposed accessible parts.
Use on AC voltmeter to measure across both terminals of load Z.
See figure2 and following table.

Leakage current ratings for selected are as

SAFETY & PRECAUTIONS

AC Line Voltage Region Load Z

100V Japan

1k

Ω

15k

µ

110 to 130V USA &Canada

110 to 130V
200 to 240V

Europe

Australia

1k

2k

50k

F

Ω

Ω

Ω

NOTE

This table is unofficial and for reference only. Be sure to confirm the precise values
for your particular country and locality.

Leakage Cur-

rent(

i

)

i

[

1mArms

i

[

0.5mArms

i

[

0.7mA peak

i

[

2mAdc

i

[

0.7mA peak

i

[

1mAdc

Clearance Distance(d),(d’)

Exposed accessible parts

Exposed accessible parts

Antenna earth terminals

Other terminals

3

EXTERNAL VIEWS

1. FRONT VIEWS FUNCTION

DV-T7C1 FRONT VIEW

DV-T7E1 FRONT VIEW

DV-T7L1 FRONT VIEW

DV-T7M1 FRONT VIEW

4

DV-T7J1 FRONT VIEW

DV-T7D1 FRONT VIEW

EXTERNAL VIEW

DV-T7B1 FRONT VIEW

DV-T8T1 FRONT VIEW

DV-T8W1 FRONT VIEW

POWER REWIND / REVIEW

STOP / EJECT FAST FORWARD / CUE
RECORD PLAY BACK
FRONT VIDEO/AUDIO INPUT JACK CHANNEL UP / DOWN

5

EXTERNAL VIEWS

2. REAR VIEWS FUNCTION

MONO 1 SCART TYPE REAR VIEW

MONO 2 SCART TYPE REAR VIEW

HI-FI 2 SCART TYPE REAR VIEW

MONO RCA TYPE REAR VIEW

HI-FI RCA TYPE REAR VIEW

6

ELECTRICAL ADJUSTMENT

1. PLAYBACK PHASE

ITEM MODE

6.5H

ADJUSTMENT

PCB : MAIN - TOP VIEW

PLAY [REC] BUTTON

TMI
BLOC

ADJUSTMENT

POINT

CHECK POINT

PIN 4 & PIN 5

OF P504

TEST

EQUIPMENT

OSCILLOSCOPE DP-2 NO SIGNAL

TEST
TAPE

ADJUSTMENT PARTS MEASURING POINT

P503

PRE­AMP

TO PATH JIG

OSCILLOSCOPE

CH1 CH2

INPUT

SIGNAL

PATH JIG

ADJUSTMENT PROCEDURE

1. Play back the test tape. (DP-2)

2. Set the oscilloscope to the CHOP mode. Connect CH1 to the SW PULSE (PIN 4 of P504)

3. Connect CH2 to the ENVE signal (PIN5 of P504)

4. Insert PATH JIG and press "REC" button on the remote control.

5. Check the position of the V-sync from the rising edge of the SW pulse.

(Standard : 6.5H ± 0.5H)

7

SPECIFICATIONS

GENERAL

Power Requirement
Power Consumption
Temperature

Operating position
Dimensions (W x H x D)
Weight
Format
Tape Width
Tape Speed

Maximum Recording Time with full-size cas­sette

VIDEO

Signal system
Recording system

Input
Output
Signal-to-Noise ratio

Horizontal resolution

AUDIO

Recording system
Input
Output

Frequency Range
Signal to Noise Ratio
Audio Distortion

TUNER

Tuning system
RF Output

TIMER

Memory programmable
Back up time
Clock exactness

ACCESSORIES

Provided Accessories Remote control unit, RF Cable, Battery

AC 230V, 50Hz
Max. 17W (in REC mode)
5×C ~ 35×C (Operating)

-20×C ~ 60×C
Horizontal only
360 x 90 x 288 (mm)
Approx. 3.85 Kg
VHS standard

12.65mm
(SP) : 23.39mm/sec
(LP) : 11.70mm/sec
(SP) :240min, with E-240 video cassette
(LP) :480min, with E-240 video cassette

PAL/SECAM colour and CCIR monochrome signals, 625 lines/50 fields
Rotary two-head helical scan with a slant double-azimuth combination video
head

1.0Vp-p, 75ohms, unbalanced

1.0Vp-p, 75ohms, unbalanced
45dB (Rhode & Schwarz noise meter) with NETTETE IMAGE control at cen­ter position
240 lines with NETTETE IMAGE control at center position

Longitudinal track

-8dBm, (CENELEC standard),more than 47 k-ohms, unbalanced

-6dBm, (CENELEC standard), less than 1k-ohms, unbalanced(100k-ohms,
load)
100Hz to 8,000Hz
More than 38dB
Less than 3% (SP)

Voltage synthesized tuner Programmable V/S 99CH (Hyper band)
UHF channel 21~69 (52)

99 CH
Less than 1 Hour
In accordance with the exactness of power supply frequency (50Hz)

*

Design and specification can be subjected to change without notice.

CHANNEL COVERAGE

SECAM-L

SYSTEM

CHANNEL

PAL, SECAM-B/G, PAL-I/I

PAL, SECAM-B/G, D/K, HYPER BAND

VHF Ch 2~12

UHF Ch 21~69

CATV Ch X,Y,Z S1~S41

INPUT/OUTPUT JACK TYPE

Model

Jack Type

EUROPE Asia, South Africa, Australia

SCART Type RCA Jack (Phone Jack)

PAL-I

UHF Ch 21~69

8

VOLTAGE CHART

SECAM.L IC
(IC361, LA7358M)

PIN NO. REC PB

1 2.5 2.5
2 2 2
3 4 4
4 - ­5 0 0
6 3 3
7 0 0
8 0 0

9 2.6 2.6
10 2.6 2.6
11 2.4 2.4
12 2.6 0
13 4.4 4.4
14 2.6 2.6
15 3 2
16 2.8 2.8
17 0 5.1
18 0 2.6
19 2.1 2.1
20 2.3 2.3
21 2.6 2.6
22 2.6 2.6
23 5 5
24 5 5
25 3 3
26 3 3
27 4.5 2.8
28 4.5 0.1
29 - ­30 - -

PDC/VPS IC
(IC151, LC74793)

PIN NO. REC PB

1 0 0
2 2.64 2.68
3 2.68 2.72
4 0 0
5 0 0
6 3.7 3.7
7 3.9 3.9
8 4.98 5.12

9 0 4.74
10 0 0
11 1.63 3.18
12 1.63 3.18
13 0.82 1.35
14 0.01 0.01
15 5.09 5.12
16 2.75 3.02
17 2.55 2.57
18 4.67 4.72
19 5.01 5.02
20 4.99 5.06
21 0 0
22 3.74 3.79
23 5.05 5.11
24 5.08 5.13

EEPROM
(IC503, ATM24C16)

PIN NO. REC PB

1 0 0
2 0 0
3 0 0
4 0 0
5 3.9 3.9
6 3.9 4
7 0 0
8 5.24 5.29

MOTOR DRIVE IC
(IC502, KA3082)

PIN NO. REC PB

1 0 0
2 0.55 0.55
3 8.78 0.88
4 6.24 6.24
5 0.01 0.01
6 0.01 0.01
7 12.12 11.74
8 12.12 11.74
9 0.91 0.91

10 0.55 0.55

9

VOLTAGE CHART

A/V ICHIP IC (IC301, LA71598M)

PIN NO.

1 2.5 2.5 26 0 - 51 1.9 1.9 76 2.5 2.5
2 2.5 2.5 27 - - 52 2.4 2.4 77 - 0
3 2.5 2.5 28 - - 53 0 0 78 2.5 2.5
4 2.5 2.5 29 0.8 0.8 54 2.4 2.4 79 2.5 2.5
5 2.5 2.5 30 0 1.0 55 5.0 5.0 80 2.5 2.5
6 2.5 2.5 31 2.1 2.1 56 0.5 0.5 81 0 0
7 2.5 2.5 32 1.8 1.8 57 3.4 3.4 82 4.1 1.8
8 0 0 33 2.0 2.0 58 5.0 5.0 83 0 0

9 0 0 34 1.8 1.8 59 3.4 3.4 84 4.1 1.8
10 - - 35 3.5 3.5 60 3.5 3.5 85 4.1 1.8
11 - - 36 1.8 1.8 61 3.3 3.3 86 0 0
12 - - 37 4.9 4.9 62 3.5 3.5 87 5.0 5.0
13 1.5 1.5 38 1.8 1.8 63 4.0 4.0 88 4.1 1.8
14 1.7 1.5 39 4 4 64 2.2 2.2 89 0 0
15 2.2 2.2 40 5 5 65 2.4 2.4 90 4.1 1.8
16 5 5 41 2.7 2.7 66 2.8 2.8 91 4.1 1.8
17 0.05 3 42 3.0 - 67 4.0 4.0 92 1.6 ­18 2.1 1.8 43 1.9 1.9 68 0 0 93 - ­19 2.1 2.1 44 - - 69 2.0 2.0 94 0.7 0.5
20 2.8 2.8 45 1.8 1.8 70 2.0 2.0 95 0 0
21 2.1 2.1 46 1.9 1.9 71 2.5 2.5 96 2.5 2.5
22 0 0 47 2.0 2.0 72 2.5 0.3 97 0 0
23 - - 48 2.3 2.3 73 2.5 2.5 98 2.5 2.5
24 - - 49 1.2 1.2 74 - 2.0 99 4.3 5.0
25 1.8 1.8 50 0 0 75 5 5 100 2.5 2.5

REC PB

PIN NO.

REC PB

PIN NO.

REC PB

PIN NO.

REC PB

A/V SW IC (IC601, LA7148M)

PIN NO.

1 3 3 10 6 6 19 0 0 28 2.8 2.8

2 12 12 11 0 0 20 6 6 29 2 2

3 3 3 12 6 6 21 6 6 30 3 3

4 12 12 13 0 0 22 6 6 31 2 2

5 3 3 14 6 6 23 6 6 32 - -

6 6 6 15 0 0 24 6 6 33 - -

7 6 6 16 6 6 25 6 6 34 0 0

8 6 6 17 0 0 26 6 6

9 0 0 18 0 0 27 6 6

REC PB

PIN NO.

REC PB

PIN NO.

10

REC PB

PIN NO.

REC PB

HI-FI IC (IC251, TDA9605H)

VOLTAGE CHART

PIN NO.

1 0 0 12 0 0.03 23 3.85 3.81 34 9.42 9.36

2 3.81 3.81 13 3.83 3.83 24 3.86 3.77 35 4.21 0.53

3 3.81 3.81 14 0 0 25 3.86 3.85 36 4.2 0.53

4 0 0 15 3.33 3.31 26 0.74 0.7 37 4.18 0.53

5 0 0 16 4.56 4.56 27 0 0 38 4.2 0.17

6 3.81 3.81 17 4.55 4.56 28 3.82 3.82 39 0 0

7 3.81 3.81 18 3.31 3.29 29 3.85 3.82 40 5.05 5.09

8 3.81 3.81 19 4.56 4.56 30 0.72 0.7 41 0.93 0.94

9 3.81 3.81 20 4.56 4.56 31 3.86 3.81 42 3.75 3.7
10 3.81 3.81 21 4.56 4.56 32 3.86 3.79 43 3.95 4
11 3.81 3.81 22 3.81 3.81 33 3.86 3.77 44 1.74 2.1

NICAM IC (IC051, MSP3417DQ)

PIN NO.

1 0.03 27 0
2 2.29 28 0
3 0.01 29 0
4 0.01 30 3.69
5 0 31 3.7
6 4.95 32 0
7 3.95 33 8.25
8 3.7 34 6.57
9 0 35 0

10 0 36 3.66
11 0 37 0
12 0 38 0
13 0 39 3.68
14 0 40 3.68
15 0 41 3.68
16 4.95 42 3.68
17 0 43 2.54
18 0.01 44 3.69
19 0 45 0
20 5.1 46 4.92
21 0 47 1.5
22 0 48 1.5
23 0 49 0

REC PB

EE

PIN NO.

PIN NO.

EE

REC PB

A2 IC (MSP3407DQ)

PIN NO.

PIN NO.

EE

1 0.01 27 0
2 0 28 0
3 0.01 29 0
4 0.01 30 3.72
5 0 31 3.73
6 5.02 32 0
7 3.6 33 8.15
8 3.3 34 6.47

9 2.47 35 0
10 2.46 36 3.68
11 2.43 37 0
12 0.02 38 0
13 0.03 39 3.71
14 0.02 40 3.71
15 0.02 41 3.71
16 5.02 42 3.71
17 0 43 2.57
18 0.02 44 3.72
19 0.01 45 0
20 5.12 46 4.98
21 0 47 1.51
22 0 48 1.51
23 0 49 0

REC PB

PIN NO.

EE

PIN NO.

REC PB

11

VOLTAGE CHART

PIN NO.

24 1.66 50 0
25 1.69 51 2.32
26 0 52 2.26

EE

PIN NO.

EE

PIN NO.

24 1.69 50 0
25 1.7 51 2.35
26 0 52 2.27

EE

PIN NO.

EE

TMI (RF101, LGTMI-SLQ1-S)

PIN NO.

1 4.83 4.9 7 31.9 31.9 13 4.9 0 19 1.08 0
2 0 0 8 1.91 0 14 4.9 0 20 0.23 0.03
3 3.7 3.7 9 0 0 15 0 0 21 2.43 0
4 4.85 4.9 10 0 0 16 31.9 31.9 22 2.01 0.01
5 4 3.9 11 3.9 4 17 0 0 23 2.69 0
6 0 0 12 3.7 3.7 18 0 0 24 2.74 0

REC PB

PIN NO.

REC PB

PIN NO.

REC PB

PIN NO.

REC PB

REGULATOR IC
(IC802, KA431AZ)

PIN NO.

1 2.49 2.49
2 0 0
3 4.82 4.82

REC PB

12

CIRCUIT DIAGRAM

1. POWER CIRCUIT DIAGRAM (230V ONLY)

13

CIRCUIT DIAGRAM

2. SYSCON CIRCUIT DIAGRAM

14