Casio EV-2500B Service manual

EV-2500B(KX-618)

INDEX

MAY. 1995

(with price)

CONTENTS

SPECIFICATIONS ......................................................................................... 2

BLOCK DIAGRAM ........................................................................................ 3

CIRCUIT DESCRIPTION ............................................................................... 4

DISASSEMBLY ............................................................................................. 5

DIAL STRINGING DIAGRAM........................................................................ 6

ADJUSTMENT............................................................................................... 7

TROUBLESHOOTING................................................................................. 12

PRINTED CIRCUIT BOARDS ..................................................................... 13

EXPLODED VIEW ....................................................................................... 15

ELECTRICAL PARTS LIST......................................................................... 16

MECHANICAL PARTS LIST ....................................................................... 23

IC AND TRANSISTOR LEAD IDENTIFICATION ........................................ 25

SCHEMATIC DIAGRAMS ........................................................................... 27

WAVEFORMS.............................................................................................. 29

— 1 —

SPECIFICATIONS

Item Specification

1. Reception channels TV— VHF: 2 ~ 13 ch UHF: 14 ~ 69 ch RADIO— FM: 88~108 MHz AM: 530~1710 KHz

2. Power voltage DC 6.0 V

3. Power consumption Approx. 3.5 W

4. Current consumption Approx. 580 mA

5. Battery life (with alkaline batteries) Approx. 11 hours

Batteries : 3 D size batteries

6. Power supply Car adaptor : CA-K65 AC adaptor : AD-K65, 64

Earphone jack : 3.5ø mini

7. Connection terminals External power jack : 6.0 V DC IN External antennea jack : 3.5ø mini Audio / Video jack : 3.5ø

8. Screen size 2.5 inches

9. No. of Picture element 61,380 (220 × 279) dots

10. Dimensions 115 (W) × 61.7 (D) × 112 (H) mm 4 1/2 (W) × 2 2/5 (D) × 4 2/5 (H)

11. Weight 360 g excepting batteries

12.7 oz excepting batteries

AC adaptor : AD-K65,64

12. Options Car adaptor : CA-K65 RF connector : CF-13 Antenna matching device : AS-35S

— 2 —

Antenna

BLOCK DIAGRAM

Power Supply

1 TU200 2 Q200

IF Amp.Tuner

IC270

Tuning Voltage Generator

VCC1 (4.5 ± 0.05 V) VCC2 (4.5 ± 0.05 V) VCC7 (25.9 ~ 31.3 V) VCC6 (10.0 ~ 12.0 V) VEE1 (–8.0 ~ –7.0 V) VEE2 (–18.4 ~ –16.0 V)

3 IC200

Video Sound Det. FM AFT Circuit AGC Circuit

Det

IC300

Chroma Circuit

IC700

Display Control Auto-Tuning Control

4 IC600 Speaker

VR600

Audio

Amp. Volume Control

LCD

1 — Color tuner: TU200 TEPU5-02

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 tuner TU200 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 IR3P90Y

Generates the tricolor (red, green, and blue) from the video signal.

6 — Display control/Auto-tuning control: IC700 MSM6770GS

Controls the display.

7 — Tuning voltage generator: IC270 BA10358F

Generates the tuning voltage with the tuning pulse output from 6.

— 3 —

POWER SUPPLY

CIRCUIT DESCRIPTION

6.3 V 220C100

CP105

D100

R107

MA141K 33K B6800p

D110

2.2

C105

Q101

2SD1819A-R

MA3051-L

0R00

R100

BH102K

TM100

VR100

270K

R108

Q110 2SD1819A-R

C137

C140

CH470p

3.3K

R105

270

R110

Q111

2SD1119-R

R115

100

2.2KR113

C145

B1500p

T100

LC12U-35

CP106

GND

D158 MA143A

C146

D156 MA141K

2 D154 MA142WK

D152

MA142WK

D150

MA142WK

OPEN

CP112

C110 25 V 10

R160

C112 16 V 47

L101

100u

C114 6.3 V 100

L103

100u

L102

100u

C116 6.3 V 100

C118 16 V 22

VCC2-3 (4.5 V)

VCC2-2 (4.5 V)

VCC7 (25.9 ~ 31.3 V)

CP110

VCC6 (10.0 ~ 12.0 V)

CP111

VCC2-1 (4.5 V)

CP113

VEE1 (-8.0 ~ -7.0 V)

CP114

VEE2 (-18.4 ~ -16.0 V)

CP115

C120 35 V 22

R161 33K

Figure 1

The power supply consists of a DC-DC converter and the associated circuit and supplies the voltages as shown in Table 1.

Name Voltage Function

VCC2-1 4.50 ± 0.02 V Main voltage

VCC7 25.9 ~ 31.3 V Tuning voltage VCC6 10.0 ~ 12.0 V Display voltage

VEE1 –8.0 ~ –7.0 V Display voltage VEE2 –18.4 ~ –16.0 V Display voltage

Table 1

— 4 —

DISASSEMBLY

1. Remove the battery case.

2. Remove the three screws and the lower case.

3. Remove the three knobs.

4. Remove the screw and resolder the two wires for the speaker.

5. Remove the PCB ass'y.

— 5 —

DIAL STRINGING DIAGRAM

Turn the pulley counterclockwise.

Sliding pointer

0.8 mm

Wrap around 4 times.

— 6 —

ADJUSTMENT

TV Items to Be Adjusted

Item Measuring Instrument

VCC2-1 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

Tint adjustment TV signal generator, pattern generator, oscilloscope AGC adjustment TV signal generator, pattern generator, IF levelmeter Vcom adjustment Photo diode, photo sensor amp., bandpass filter, oscilloscope Free-Running frequency adjustment

Frequency counter

RADIO

When the radio is defect, replace the radio PCB unit.

Adjustment and Test Point Locations

T201 T200

VR740

VR200

VR303

VR301

Top View

— 7 —

VR300

VR100

IF Pad

TP2(CP201)

TP4(CP217)

TP7(CP204)

TP8(CP320)

TP5(CP323)

TP6(CP311)

Bottom View

Equipment Connection / Adjustment Procedure

VCC2-1 Voltage Setting

TP3(CP218)

TP1(CP113)

EV-2500

16-169

set

Output

TP1

Input Input Input Output Output

Connection Point Signal Connection Point

Adjust Result

VR100

Voltmeter

— 8 —

Voltmeter

TP1

Adjust to obtain a 4.50 ± 0.02 V reading on the voltmeter.

* Desolder the IF pad to open.

Pattern generator

Signal generator

Video Detection Coil Adjustment

EV-2500

set

Low-pass filter

Input TP2

Output

TP3

Oscilloscope

Input Input Input Output Output

Connection Point Signal Connection Point

Pattern

Color bar

generator Signal

generator

TP2 T200 TP3

45.75 MHz 45 ± 3 dBµ

Adjust Result

Low-pass filter Oscilloscope

AFT Coil Adjustment

* Desolder the IF pad to open.

Sweep generator

Input TP2

EV-2500

set

Oscilloscope

Output

TP4

38.9 ± 5 MHz

Sweep generator

(sweep) marker:

TP2 T201 TP4

45.75 MHz

Voltmeter Oscilloscope

70 ± 3 dBµ

Adjust to obtain the minimum DC level.

Voltmeter

Adjust to obtain a 1.4 ± 0.2 V reading on the voltmeter. Confirm that the marker is at the middle of the S-curve on the oscilloscope.

* Desolder the IF pad to open.

Pattern generator

TP2 VR300 TP5

Color bar

45.75 MHz

Signal generator

70 ± 3 dBµ

Signal generator

Contrast Adjustment

EV-2500

set

Input TP2

Oscilloscope

— 9 —

Vcc2-3

10 kohm

CP312 (KILLER)

Output TP5

Adjust so that the step form wave becomes 2.2 ± 0.1 Vp-p.

Oscilloscope

2.2 ± 0.1 V P.P

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