Casio TV-1750C, TV-1750D Service manual

(with price)

POCKET TELEVISION
TV-1750C
TV-1750D
MAR. 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

INDEX

R

SPECIFICATIONS

Item			Specification
			VHF	UHF
Reception Channels	TV-1750C		2 ~ 12 ch	21 ~ 69 ch
	TV-1750D		–	21 ~ 68 ch
Power Voltage	DC 6.0 V
Power Consumption	Approx. 3.3 W
Current Consumption	Approx. 550 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 —

BLOCK DIAGRAM

Antenna

			3	IC200	4	IC600	Speaker
1	TU200	2	Q200	Video
					VR600
				Sound Det.		Audio
	Tuner		IF Amp.	FM		Amp.
				AFT Circuit	Volume
				AGC Circuit	Control

7	IC500	5	IC300
Tuning
Voltage			Chroma	Common	LCD
Generator			Circuit	Driver
		6	IC700
		Osc.
		Display			Segment
		Control
		A-D Converter			Driver
		Auto-Tuning
		Control
		8	Q800~Q806
		VR800	Display
Power	VCC2 (3.95V)
	VCC7 (41.6~51.6V)		Voltage
Supply
	VEE1 (-6.5~-8.0V)	Brightness	Generator
		Control

1— Color Tuner: TU200 TEPE5-01(TV-1750C) TU200 TEPB5-02(TV-1750D) 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 —

CIRCUIT OPERATIONS

IC700

TE2

TE4

TE6

VSS2

TE1

TE3

TE5

M6 M5 M4 M3 M2 M1

AFT

Key

KDB

KCB

Switch

AD2

AFT

AVB

Control

Test Control

Mode Control

Control

UHF

AD1

B

Test

G

Circuit

Frequency

Sweep

Mute

R

A/D

Divider

Control

Control

MTB

Tuning Control

RLL

Channel

VLB

Tuning Voltage

VDD2

bar

UP/DOWN Counter

Synchronism

Control

RHH

Judgment

Pulse Width

Modulation D/A

TU

M7

Frequency

M8

Separator

M9

Mode

VDD1

Control

Phase

C-S

M10

Comparator

PD

PSi

Display

VSS1

Control

Vertical

Horizontal

Frequency

Oscillator

OSC1

Data Output

positioning

positioning

Divider

Control

Control

OSC2

D1

D2

D3

D4

D5

D6

CDB CFB CNB ECB

SNB SCB STB HDB

CK1 CK2

Signal Name	Function	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

— 5 —

BOTTOM VIEW

3) Equipment Connection / Procedure

	VCC2 Voltage Setting
TV-1750	Voltmeter
Set
	Output
	TP1

Input

Input

Input

Adjust

Output

Output

Result

Connection

Point

Signal

Connection

Point

VR100

Voltmeter

TP1

Adjust for 4.30 ± 0.02V

reading on voltmeter.

— 6 —

Video Detection Coil Adjustment

* Open soldering pad IF.

Pattern

Signal

TV-1750

generator

generator

Set

Oscilloscope

Low-pass

Input

Output

filter

TP2

TP3

Input

Input

Input

Adjust

Output

Output

Result

Connection

Point

Signal

Connection

Point

Pattern

Color bar

generator

TP2

38.9MHz(TV-1750C)

T200

Low-pass filter

TP3

Adjust for DC level at mini-

Signal

39.5MHz(TV-1750D)

Oscilloscope

generator

40±3dBμ

AFT Coil Adjustment

* Open soldering pad IF.

Sweep	TV-1750	Oscilloscope	Voltmeter
generator	Set
Input		Output
TP2		TP4

38.9±5MHz (Sweep)

Adjust for 2.0 ± 0.2V reading on

Sweep

: TV-1750C

Voltmeter

voltmeter.

TP2

39.5±5MHz (Sweep)

T201

TP4

Confirm that the marker is at

generator

: TV-1750D

Oscilloscope

Maker: 38.9MHz(TV1750C)

the middle of S-curve on oscil-

Maker: 39.5MHz(TV1750D)

loscope.

70dBμ

Contrast Adjustment

* Open soldering pad IF.

Pattern

Signal

TV-1750

generator

generator

Set

Oscilloscope

Input

Output

TP2

TP5

Pattern

Color bar

generator

TP2

38.9MHz(TV-1750C)

VR300

Oscilloscope

TP5

Adjust step form wave to read

Signal

39.5MHz(TV-1750D)

0.90 ± 0.05 Vp-p.

generator

70dBμ

— 7 —

AGC Adjustment

Pattern	Signal	TV-1750
generator	generator	Set	IF levelmeter
	Input		Output
	TP7		TP2

Input

Input

Input

Adjust

Output

Output

Result

Connection

Point

Signal

Connection

Point

Pattern

Adjust for 84 ± 1 dBμ

generator

TP7

Color bar

VR200

IF levelmeter

TP2

TV signal

65 ± 5 dBμ

reading on the IF levelmeter

generator

Clock Adjustment

TV-1750	Voltmeter
Set
	Output
	TP6

Adjust for 1.05 ± 0.05V

VR700 Voltmeter TP6

reading on voltmeter.

— 8 —