DAEWOO ST7C3 Service Manual
Service Manual
Video Cassette Recorder
ALL T-MECHA (Hi-Fi/MONO)
Model: (PAL/SECAM MODELS)
DVST7C3_(ST-821)
TABLE OF CONTENTS
SAFETY&PRECAUTIONS................................................................................................ 2
EXTERNAL VIEWS......................................................................................................... 4
FRONT VIEWS FUNCTION.................................................................................................................... 4
REAR VIEWS FUNCTION...................................................................................................................... 6
ELECTRICAL ADJUSTMENT............................................................................................ 7
SPECIFICATIONS ......................................................................................................... 8
CIRCUIT INFORMATION............................................................................................... 9
INTERCONNECT WIRING DIAGRAM..................................................................................................... 9
POWER CIRCUIT DIAGRAM................................................................................................................. 10
POWER BLOCK DIAGRAM.................................................................................................................. 12
SYSCON CIRCUIT DIAGRAM............................................................................................................... 13
SERVO & SYSCON BLOCK DIAGRAM.................................................................................................. 15
A/V & SECAM COLOR CIRCUIT DIAGRAM........................................................................................... 16
VIDEO PLAYBACK/RECORD PATH FOR PAL.......................................................................................... 18
HIFI & SW CIRCUIT DIAGRAM.............................................................................................................. 19
PIF CIRCUIT DIAGRAM........................................................................................................................ 21
COMPONENTS LOCATION GUIDE ON PCB BOTTOM VIEW............................................ 23
PCB MAIN.......................................................................................................................................... 23
DISASSEMBLY ............................................................................................................. 24
PACKING ASS’Y ................................................................................................................................. 24
FRONT PANEL ASSEMBLY ................................................................................................................... 25
INSTRUMENT DISASSEMBLY ................................................................................................................. 29
ELECTRICAL PARTS LIST ............................................................................................... 30
PCB MAIN AS .................................................................................................................................... 30
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.)
is
greater 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 & Canada
Latin America
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)
(a :Power cord)
>
>
>
>
8(d')
3
3.2
6(d)
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
110 to 130V USA &Canada
110 to 130V
200 to 240V
Europe
Australia
1k
2k
50k
15kmF
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
<
1 mArms
i
<
0.5mArms Exposed accessible parts
i
<
0.7mA peak
i
<
2mAdc
i
<
0.7mA peak
i <
1mAdc
Clearance Distance(d),(d’)
Exposed accessible parts
Antenna earth terminals
Other terminals
3
EXTERNAL VIEWS
1. FRONT VIEWS FUNCTION
DVST7C3 FRONT VIEW
EXTERNAL VIEWS HI-FI 2 SCART TYPE REAR VIEW
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 P502
TEST
EQUIPMENT
OSCILLOSCOPE DP-2 NO SIGNAL
TEST
TAPE
ADJUSTMENT PARTS MEASURING POINT
P502
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 P502)
3. Connect CH2 to the ENVE signal (PIN5 of P502)
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
CIRCUIT INFORMATION
1. INTERCONNECT WIRING DIAGRAM
9
CIRCUIT INFORMATION
2. POWER CIRCUIT DIAGRAM
10
CIRCUIT INFORMATION
POWER MODE
LOC. PIN EE PLAY REC.
IC802 1 2.46 2.46 2.46
2 4.81 4.83 4.82
3 0 0 0.01
IC801 1 5.88 5.89 5.89
/803 2 4.81 4.83 4.83
3 0.25 0.25 0.25
4 3.1 3.1 3.1
POWER MODE
LOC. PIN EE PLAY REC.
Q801 E 0 0 0
B -0.12 -0.11 -0.72
C 323 323 323
Q802 E 0 0 0
B 0.25 0.26 0.17
C 0.12 0.11 0.17
Q821 E 12.58 12.6 12.6
B 13.2 13.2 13.2
C 15.6 15.36 15.4
Q822 E 5.2 5.19 5.2
B 5.89 5.89 5.89
C 5.97 5.97 5.96
Q825 E 0 0 0
B
C 5.89 5.89 5.89
Q826 E 0 0 0
B 0.73 0.73 0.73
C
1. T801 PIN 1 X : 0.1KV DIV
Y : 5uS DIV
4. IC801 PIN3 X : 0.5V DIV
Y : 5uS DIV
2. T801 PIN 3 X : 2V DIV
Y: 2mS DIV
5. IC801 PIN 4 X: 2V DIV
Y : 5uS DIV
3. T801 PIN4 X: 5V DIV
Y: 5uS DIV
6. Q801 base X: 0.5V DIV
Y : 5uS DIV
11
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