Casio EV-500B Troubleshooting guide

R
(without price)
EV-500B(KX-615)
FEB. 1995
INDEX

— 1 —
CONTENTS
SPECIFICATIONS ......................................................................................... 2
BLOCK DIAGRAM ........................................................................................ 3
CIRCUIT DESCRIPTION ............................................................................... 4
ADJUSTMENT............................................................................................... 5
TROUBLESHOOTING................................................................................. 10
PRINTED CIRCUIT BOARDS ..................................................................... 11
WIRING DIAGRAM ...................................................................................... 13
EXPLODED VIEW ....................................................................................... 14
ELECTRICAL PARTS LIST......................................................................... 15
MECHANICAL PARTS LIST ....................................................................... 21
IC AND TRANSISTOR LEAD IDENTIFICATION ........................................ 22
SCHEMATIC DIAGRAMS ........................................................................... 24
WAVEFORMS.............................................................................................. 26

— 2 —
SPECIFICATIONS
Item Specification
1. Reception channels
2. Power voltage DC 6.0 V
3. Power consumption Approx. 3.7 W
4. Current consumption Approx. 617 mA
5. Battery life (with alkaline batteries) Approx. 2.0 hours
Batteries : 3 AA size batteries
6. Power supply Car adaptor : CA-K65
AC adaptor : AD-K65
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 75 (W) ×26.7 (D) ×120.8 (H) mm
3 (W) ×1 (D) ×4 3/4(H)
11. Weight 191 g excepting batteries
6.7 oz excepting batteries
12. Standard accessories Test batteries (R6 ×3)
AC adaptor : AD-K65,64
13. Options Car adaptor : CA-K65
RF connector : CF-13
Antenna matching device : AS-35S
14. Body color Black
VHF: 2 ~ 13 ch UHF: 21 ~ 69 ch

— 3 —
Antenna
1 TU200 2 Q200 3 IC200
7
Tuning
Voltage
Generator
VR600
Volume
Control
4 IC600 Speaker
IC300
IC700
LCD
Chroma
Circuit
Display
Control
Auto-Tuning
Control
5
6
VCC2 (4.5 ± 0.02 V)
VCC7 (25.9 ~ 31.3 V)
VCC6 (10.8 ~ 12.0 V)
VEE1 (–8.5 ~ –7.5 V)
VEE2 (–19.8 ~ –17.2 V)
IC270
Power
Supply
Audio
Amp.
IF Amp.Tuner
Video
Sound Det.
FM
AFT Circuit
AGC Circuit
Det
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
Eliminatesthe carrier waveinthe video IFsignal,and picks upthevideo signal andthesound 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.
BLOCK DIAGRAM

— 4 —
Vcc1-1
CP100
R108
270K
R110
270
Q110 2SD1819A-R
Q111
2SD1119-R
C137
R107
D100
MA142WK 33K B6800p
C140
CH470p R115
100
6.3 V 220C100
D110
MA3051-L
2.2
BH102K
TM100
Q101
2SD1819A-R
2.2KR113
R105
3.3K
VR100
2K
C105
GND
C145
B1500p
CP101
1
2
9
6
3
4
5
6
7
8
T100
LC12U-35 D158 MA143A R160
68
C146 220p
D156 MA142WK
D154 MA142WK
D150
MA142WK
D152
MA142WK
L101
100u
L102
330u
CP110
CP111
CP113
CP114
CP115
C110 25 V 10 C114 6.3 V 220 C116 6.3 V 220 C120 35 V 22 R150 33K
Vcc2-2
Vcc7 (29.5 V)
Vcc6 (11 V)
Vcc2-1 (4.5 V)
VEE1 (-7.5 V)
VEE2 (-18 V)
GND
(3.9 V)
C112 16 V 47 C118 16 V 22 C150 OPEN
CIRCUIT DESCRIPTION
POWER SUPPLY
Figure 1
Name Voltage Function
VCC2-1 4.50 ±0.02 V Main voltage
VCC7 25.9 ~ 31.3 V Tuning voltage
VCC6 10.8 ~ 12.0 V Display voltage
VEE1 –8.5 ~ –7.5 V Display voltage
VEE2 –19.8 ~ –17.2 V Display voltage
Table 1
The power supply consists of a DC-DC converter and the associated circuit and supplies the voltages as shown
in Table 1.

— 5 —
ADJUSTMENT
LINEAR PCB
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
Adjustment and Test Point Locations
Top View
T201T200
VR100

— 6 —
VCC2-1 Voltage Setting
Input Input Input Output Output
Connection Point Signal Connection Point
Adjust Result
Adjust to obtain a 4.50 ±0.02 V
reading on the voltmeter.
Voltmeter
VR100 TP1
TP1
16-169
Equipment Connection / Adjustment Procedure
Bottom View
Output
Voltmeter
EV-500
set

— 7 —
Video Detection Coil Adjustment
TP2 VR300 TP5
Pattern
generator
Signal
generator
Oscilloscope
* Desolder the IF pad to open.
Contrast Adjustment
TP2 T201 TP4
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.
AFT Coil Adjustment
Pattern
generator
Signal
generator
TP2 T200 TP3
Input Input Input Output Output
Connection Point Signal Connection Point
Adjust Result
* Desolder the IF pad to open.
Voltmeter
Oscilloscope
Sweep
generator
Pattern
generator Signal generator
Input
TP2
Oscilloscope
Vcc2-3
EV-500
set
Adjust so
that the step
form wave
becomes 2.2
±0.1 Vp-p.
Adjust to obtain the minimum
DC level.
Low-pass filter
Oscilloscope
Input
TP2
EV-500
set
Output
TP3
Low-pass
filter
Pattern
generator Signal generator Oscilloscope
Sweep
generator EV-500
set
Input
TP2 Output TP4
Voltmeter
Oscilloscope
Output
TP5
2.2 ± 0.1 V
P.P
Color bar
45.75 MHz
45 ±3 dBµ
45.75 ±5 MHz
(sweep) marker:
45.75 MHz
70 ±3 dBµ
Color bar
45.75 MHz
70 ±3 dBµ
10 kohm
CP312 (KILLER)

— 8 —
Adjust VR301 so that the
difference
between pulses
A and B is less
than 0.2 V.
* Desolder the IF pad to open.
BCC Adjustment
Signal
generator
Pattern
generator EV-500 set Oscilloscope
Input
TP2 Output CP339(VC)
5.0 ± 0.5 V
-0.5 ± 0.25 V
VR303 Oscilloscope TP8
Adjust VR303 so that the
high level of the square wave
is at -0.5
±0.25 V.
EV-500
set Oscilloscope
Output
TP8
Signal
generator
Pattern
generator EV-500 set IF levelmeter
Input
TP7 Output
TP2
* Short the IF pad.
Pattern
generator
TV signal
generator TP7 VR200 IF levelmeter TP2
Color bar
65 ±5 dBµAdjust to obtain a 84 ±2 dBµ
reading on the IF levelmeter.
Vcom Adjustment
AGC Adjustment
Pattern
generator
Signal
generator TP2 VR301 Oscilloscope TP5
Pulse BPulse A
Color bar
45.75 MHz
70 ±3 dBµ
Adjust Result
Input Input Input Output Output
Connection Point Signal Connection Point

— 9 —
Vcom Adjustment
* Place a photo diode on the middle of the display plate.
EV-500
set Photo
diode
ON
OFF
H
M
L
AV-C1
Audio/Video jack
Bandpass
filter
Oscilloscope
Photo sensor amp.
Adjust to obtain the minimum
ripple.
VR303
Photo sensor
amp.
Bandpass filter
Oscilloscope
Free-Running Frequency Adjustment
Frequency
counter
VR740 TP6
Output
TP6
Frequency
counter
EV-500
set
Adjust to obtain a reading of
15.73 ±0.1 kHz.
Adjust Result
Input Input Input Output Output
Connection Point Signal Connection Point