KV-25B5E - Sony TV Service Manual (repair manual). Page 19

19

a-d: screen-corner
convergence defect

a

b

c

d

c

a

d

b

Fit the permalloy assembly to the rear 
of the CRT to correct the area at fault.

Permalloy

FOCUS

•

If you are unable to adjust the corner convergence properly, 
this can be corrected by the use of permalloy assemblies.

1.

Input a dot signal from the pattern generator.

2.

Set the Picture, Brightness and Colour to minimum.

3.

Apply 170Vdc from an external power supply to the 
R, G and B cathodes of the CRT.

4.

Whilst watching the picture, adjust the G2 control [RV701 
SCREEN] located on the C Board to the point just before the 
flyback return lines disappear.

1.

Input a ‘PAL’ all-white signal from the pattern generator.

2.

Enter into the Service Mode.

3.

Enter into the ‘Picture’ service menu.

4.

Select the ‘Green drive’ and adjust so that the White Balance
becomes optimum.

5.

Select the ‘Blue drive’ and adjust so that the White Balance
becomes optimum.

6.

Set the Picture to MIN.

7.

Set the ‘R-cut-off’ to 07.

8.

Adjust the ‘G-cut-off’, and the ‘B-cut-off’ so that the White 
Balance becomes optimum.

9.

Press the

button to return to TV operation.

1.

Input a Phillips colour pattern

2.

Set the picture settings to normal.

3.

Adjust the focus control located on the Flyback transformer to 
bring the centre of the screen into focus.

Note :Bring only the centre area of the screen into focus, switch to an

all-white pattern and confirm that the magenta ring is hardly 
noticed. To obtain optimum focus balance the focus setting 
between optimum screen centre focus and a reduced magenta 
ring level.

PICTURE 

R - Drive

Adj

G - Drive

Adj

B - Drive

Adj

R - cut - off

Adj

G - cut - off

Adj

B - cut - off

Adj

ID - start

02

ID - stop

01

ID - level

01

Bellfo

Adj

Sub Colour

Adj

Sub Brightness

Adj