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5

2.  Single ABL

In a normal TV the ABL operation detects the current
following to the secondary coil of the flyback transformer
and controls the contrast. In a video projection TV,
however, the current for the secondary coil of the flyback
transfomer is measured as the total current for the three
projection tube. Therefore the current can not be controlled
even if most of the electron beams are sent though one
projection tube. For this reason the monochrome ABL
circuit detects the maximum current for each projection
tube and controls the same. We have added a circuit which
accelerates the ABL operation time, and lowers the
contrast.

In normal ABL operation detects the current flowing to FBT
which supplies the high voltage to the three projection
tubes, as with a standard TV. This is alike EURO5 chassis.
The current flowing to each projection tube is detected in
the colour output transistor emitter, and the maximum

current to each projection tube is then input to the Q7735
through D3352,D3362 and D3372.
Then output value of Q7735 is input to pin No. 5,7,9 and 11
of IC7705, these are compared with pin No. 4,6,8 and 10 of
IC7705.
Compared result is output from pin No..1,2,13 and 14 as
P0, P1, P2 and P3. P0-P3 data are input to IC7702, then
CRT current following is separated to 5 levels/ Ranks in the
IC7702 as follows.

P0

P1

P2

P3

RANK

LEVEL

H

H

H

H

A

Danger

H

H

H

L

B

I

H

H

L

L

C

I

H

L

L

L

D

I

L

L

L

L

E

Safety

Detection data is input to MPU through IIC bus line and
MPU controls the contrast to keep detection level safety.

R,G,B  OUT

Q7735

D3352,D3362,D3372

CRT-Anode

FBT

Q9601

4
5

7

6

8
9

11

10

2

1

13

14

+5v

10

9

2

1

14

15

69

70

43

11
10

BCL

SDA

SCL

+

-

+

-

+

-

+

-

E10 A10

16

1

P3

P2

P1

P0

LG1 W3

8

IIC bus

Q3351

Q3361

Q3371

6

3.  Shading

To correct variations in the left and right shading due to
differences in the positions of the projection tubes, to
correct gamma and to blank the final sweep interval.

Horizontal parabola wave is made by horizontal plus via
Q7741-Q7744 and Q7745-7747.  H.SAW wave and

H.PARA wave is input to Pin No. 2 and 5 of IC7704, then
they are mixed in the IC7704 and then it is output from pin
No. 7 o IC7704.
The correction wave-form output from IC7704 is input to
pins 10 and 8 of IC7703, the R and B gain is adjusted, and
then the left and right brightness are varied to correct any
lack of colour uniformity on the screen.

4.  Prevention of projection tube burn-out

This feature operates to prevent burn-out from occurring in
the phosphor substance of the projection tube when the
picture is stopped for an extended period.

Each time the power is turned off, the channel is changed,
or AV input switching is performed, the screen display
position is moved and rotated horizontally and vertically
approximately 3 mm in a clockwise direction.
The MPU sends a command to move the screen display
position horizontally and vertically, to IC9601, through the
I²C Bus, for an input from the button on the TV, or from the
remote control, to turn the power on or off, or change the
channel, or switch the AV input.

A3

W2

7

H.SAW

Q7741

|

Q7744

HP-BLK

H.PARA

Q7745

|

Q7747

ADJ.

2

Q7748

7

5

10

8

19

18

20

R-gain

B-gain

TPW101

TPW117

6

TPW2

+12V

R-out

G-out

B-out

(H.V)

(H+1.V)

(H.V+1)

(H+1.V+1)

7

5.  Single colour mode

During the service mode, each colour (R,G and B) can be
displayed by “HELP” key of remote control.
Command data is sent to IC7707(DAC) from IC1101(MPU)
via IIC bus line.
Then the voltage is output from pin No.1, 2 and 9 of IC7707
as follows.

IC7707 Pin No.

1

2

9

B

H

L

H

G

L

H

H

R

H

H

L

R+G+B

L

L

L

Above voltage are applied to Q7718, Q7717 and Q7715 as
blanking plus though Q7728-30.

69

70

CLK

DATA

16

1

2

B BLK

9

G BLK

R BLK

14

15

+9V

+9V

Q7730

Q7729

Q7728

1

2

B

9

G

R

Q7718

Q7717

Q7715

8

6.  Protection

To prevent smoke, fire and the radiation of X-rays due to

abnormally high voltages by using detection circuits (listed

below) to instantly turn off the power in the event of a

problem. Also, depending on the circuit, the projection

tubes can be damaged in the event of a problem; therefore,

there is also a circuit that informs the blanking circuit when

a problem arises so that the video signals to the cathodes

can be blanked.

There is a circuit that prevents the power being turned on by

remote control once a problem is detected.

EURO5VP chassis has protection management IC which is

IC1103 (SOS) on A board.

Protection line of each circuit is connected to IC1103 pin

No.5-7 and 9-11.

When some of these pins go to “H”, this abnormal

information is informed to IC1101 (MPU) via IIC bus line.

Then pin No.52 of IC1101 voltage to “H”, Q1101 turns ON,

Q6751 base voltage drops to LOW and trips the RL6701.

D1111

69

70

A2/W1

7

ETC.

6

7

9

10

11

5

D1105

D1104

75

Q1109

Q1109

+35V

Q1110

+12V

Q1108

+5V

EHT.

NECK

CONV.

+.- 15V

EHT.

14

15

CLK

DATA

TPF51

D400/Q400

<VERTICAL>

TPF41

D500/Q503

D514/Q511

<EHT DET.>

D7560

<+22V/-22V>

52

Q7115 <R>

Q7117 <G>

Q7118 <B>

CRT STOP

D869

<+130V>

D861

<+15V/-15V>

Q1101

RL6701

P11/D4

4

Q6751