Casio tv1750in Schematic
(without price)
INDEX
POCKET TELEVISION
TV-1750I
TV-1750N
JULY. 1994
Page
Specifications.............................................................................................2
Block Diagram...........................................................................................3
Circuit Operations......................................................................................4
Adjustment
Linear PCB..........................................................................................5
Printed Circuit Boards................................................................................9
Electrical Parts List..................................................................................11
Mechanical Parts List...............................................................................17
Exploded View / Disassembly..................................................................18
Wiring Diagram........................................................................................19
Schematic Diagrams and Waveforms.....................................................20
R
SPECIFICATIONS
Item Specification
VHF UHF
Reception Channels TV-1750N 2 ~ 12 ch 21 ~ 69 ch
TV-1750I A ~ H2 ch 21 ~ 69 ch
Power Voltage DC 6.0 V
Power Consumption Approx. 3.6 W
Current Consumption Approx. 600 mA
Battery Life (with alkaline batteries) Approx. 2.5 hours
Batteries : 4 AA size batteries
Power Supply Car adaptor : CA-K65
AC adaptor : AD-K65
Connection Terminals Earphone jack : 3.5ø mini
External power jack : 6.0 V DC IN
Screen Size 2.5 inches
No. of Picture Element 118,800 (220 × 540) dots
Dimensions 135.5 mm (H) × 91 mm (W) × 38.1 mm (D)
Weight 240 g excluding batteries
8.5 oz excluding batteries
Options AC adaptor : AD-K65
Car adaptor : CA-K65
Body Color Black
— 2 —
Antenna
BLOCK DIAGRAM
Power
Supply
1 TU200 2 Q200
IF Amp.Tuner
7
IC500
Tuning
Voltage
Generator
VCC2 (3.95V)
VCC7 (41.6~51.6V)
VEE1 (-6.5~-8.0V)
VR800
Brightness
Control
3 IC200
Video
Sound Det.
FM
AFT Circuit
AGC Circuit
5
6
Osc.
Display
Control
A-D Converter
Auto-Tuning
Control
8 Q800~Q806
Det
IC300
Chroma
Circuit
IC700
Display
Voltage
Generator
VR600
Volume
Control
4 IC600 Speaker
Audio
Amp.
Common
Driver
LCD
Segment
Driver
1 — Color Tuner: TU200 TEPE5-01
Selects a desired radio wave and changes it to the video IF signal.
2 — Video IF Amp.: Q200 2SC4238
Amplifies the video IF signal output from the tuner TU by 10 times (20 dB).
3 — Video Det./Sound Det./FM Det./AFT/AGC: IC200 M51348FP
Eliminates the carrier wave in the video IF signal, and picks up the video signal and the sound IF signal.
Also, the sound signal is picked up from the sound IF signal by FM detection.
4 — Audio Amp.: IC600 NJM2070M
Sound amplification.
5 — Chroma Circuit: IC300 M52045FP
Generates the tricolor (red, green, and blue) from the video signal.
6 — OSC/A-D Converter/Display Control/ Auto-Tuning Control : IC700 MSM662501 GSK-640E
Converts the color signal into a digital signal.
Also, generates the clock pulse for the display and controls the display.
7 — Tuning Voltage Generator: IC500 MSC1169MS-K
Generates the tuning voltage with the tuning pulse (TU) output from 6.
8 — Display Voltage Generator: IC800 BA10358F, Q804 ~ Q806 Q810 Q811 2SD1149S,
2SD601A-R×3, 2SB709A-R
Generates the display voltages V0 ~ V4 with VEE1 and VCC7 outputs from the power supply.
— 3 —
AD2
AD1
RLL
VDD2
RHH
M7
M8
M9
M10
PSi
VSS1
IC700
B
G
R
VSS2 TE1
A/D
Mode
Control
Data Output
CIRCUIT OPERATIONS
TE2
TE4
TE5
TE6
M6 M5 M4 M3 M2 M1 AFT
Frequency
Divider
Channel
bar
Control
Vertical
positioning
Control
TE3
Test Control Mode Control
Test
Circuit
Display
Control
Sweep
Control
Tuning Control
Tuning Voltage
UP/DOWN Counter
Pulse Width
Modulation D/A
Horizontal
positioning
Control
AFT
Control
Phase
Comparator
Frequency
Divider
Key
Switch
Control
Mute
Control
Synchronism
Judgment
Frequency
Separator
Oscillator
KDB
KCB
AVB
UHF
MTB
VLB
TU
VDD1
C-S
PD
OSC1
OSC2
D1 D2 D3 D4 D5 D6 CDB CFB CNB ECB
Signal Name
Function
SCB STB HDB CK1 CK2
SNB
Signal Name
Function
D1 ~ D6 Display data output terminal MTB Mute control terminal
SNB Data latch signal TU Tuning control pulse output terminal
CDB Scanning start signal VLB VHF High/Low channel select signal
output terminal
CFB Output voltage changeover signal UHF VHF/UHF select signal
CNB Scanning signal shift lock signal AVB
KCB Key input terminal
KDB
SCB Brightness modulation pulse control AFT AFT voltage input terminal
STB Sampling start signal M1 ~ M10 Mode select signal input terminal
ECB Signal input terminal controlling the
TE1 ~ TE6
Test terminal
segment drive terminal to "H" during
no display
CK1, CK2 Clock pulse output terminal R, G, B Original color
OSC1 Oscillator freuency control terminal RLL "L" level voltage input terminal of
OSC2 video signal
PD Clock pulse adjustment terminal RHH "H" level voltage input terminal of
video signal
C-S Synchronizing pulse input terminal PS1 Mode control signal
HDB Horizontal synchronizing signal input VSS1 Power supply voltage input terminal
terminal
VDD1 VDD voltage input terminal
— 4 —
ADJUSTMENT
Linear PCB
1) Items to Be Adjusted
Item Measuring Instrument
VCC2 voltage setting Voltmeter
Video detection coil adjustment TV signal generator, pattern generator, oscilloscope,
low-pass filter
AFT coil adjustment Sweep generator, oscilloscope, voltmeter
Contrast adjustment TV signal generator, pattern generator, oscilloscope
AGC adjustment TV signal generator, pattern generator, IF levelmeter
Clock adjustment Voltmeter
2) Adjustment and Test Point Locations
TOP VIEW
TP1
T201
T200
— 5 —
BOTTOM VIEW
TP3
TP6
Pad IF
VR200
VR700
TP2
TP4
TP5
TP7
VR100
VR300
3) Equipment Connection / Procedure
VCC2 Voltage Setting
TV-1750
Set
Voltmeter
Output
TP1
Input Input Input Output Output
Connection Point Signal Connection Point
Adjust Result
VR100
Voltmeter
TP1
Adjust for 4.30 ± 0.02V
reading on voltmeter.
— 6 —
* Open soldering pad IF.
Pattern
generator
Signal
generator
Video Detection Coil Adjustment
TV-1750
Set
Input Output
TP2
TP3
Oscilloscope
Low-pass
filter
Input Input Input Output Output
Connection Point Signal Connection Point
Pattern
generator
Signal
generator
Color bar
38.9MHz
TP2 T200 TP3
40±3dBµ
Adjust Result
Low-pass filter
Oscilloscope
AFT Coil Adjustment
* Open soldering pad IF.
Sweep
generator
Input
TP2
TV-1750
Set
Oscilloscope Voltmeter
Output
TP4
38.9±5MHz
Sweep
generator
TP2 T201 TP4
(Sweep)
Maker:
38.9MHz
Voltmeter
Oscilloscope
70dBµ
Adjust for DC level at mini-
Adjust for 2.0 ± 0.2V reading on
voltmeter.
Confirm that the marker is at
the middle of S-curve on oscilloscope.
* Open soldering pad IF.
Pattern
generator
Pattern
generator
Signal
generator
Color bar
38.9MHz
TP2 VR300 TP5
70dBµ
Contrast Adjustment
Signal
generator
Oscilloscope
— 7 —
TV-1750
Set Oscilloscope
Input Output
TP2
TP5
Adjust step form wave to read
0.90 ± 0.05 Vp-p.
Loading...