Sony MDS-JE770 specifications Focus Bias Adjustment, Adjusting Procedure

11.Rotate the lAMS L knob until the waveform of the oscilloscope moves closer to the specified value.

In this adjustment, waveform varies at intervals of approx. 2%. Adjust the waveform so that the specified value is satisfied as much as possible.

(Traverse Waveform)

A

VC

B

Specification A = B

12.Press the YES button, and save the adjustment results in the non-volatile memory. (“EFB = SAVE” will be displayed for a moment.)

Next “EF MO ADJUS” (C07) is displayed. The disc stops ro- tating automatically.

13.Press the AEJECT button and remove the disc.

14.Load the check disc (MD) TDYS-1.

15.Roteto lAMS L knob and display “EF CD ADJUS” (C08).

16. Press the YES button and display “EFB = CD”. Servo is imposed automatically.

17.Rotate the lAMS L knob so that the waveform of the oscilloscope moves closer to the specified value.

In this adjustment, waveform varies at intervals of approx. 2%. Adjust the waveform so that the specified value is satisfied as much as possible.

(Traverse Waveform)

A

VC

B

Specification A = B

18. Press the YES button, display “EFB = SAVE” for a mo- ment and save the adjustment results in the non-volatile memory. Next “EF CD ADJUS”(C08) will be displayed.

19.Press the AEJECT button and remove the check disc (MD) TDYS-1.

Note 1 : MO reading data will be erased during if a recorded disc is used in this adjustment.

Note 2 : If the traverse waveform is not clear, connect the oscillo- scope as shown in the following figure so that it can be seen more clearly.

Oscilloscope

BD board 330 kΩ

CN105 pin 4 (TE)		10pF
CN105 pin 6	(VC)

MDS-JE770

5-13. FOCUS BIAS ADJUSTMENT

Adjusting Procedure :

1.Load a test disk (MDW-74/GA-1).

2.Rotate the l AMS L knob and display “CPLAY1 MODE”(C34).

3.Press the YES button and display “CPLAY1 MID”.

4. Press the	MENU/NO	button when “C =	AD = ” is
displayed.

5.Rotate the l AMS L knob and display “FBIAS ADJUS”(C09).

6.Press the YES button and display “ / a = ”.

The first four digits indicate the C error rate, the two digits after

[/]indicate ADER, and the 2 digits after [a =] indicate the focus bias value.

7.Rotate the lAMS L knob in the clockwise direction and find the focus bias value at which the C error rate becomes 220 (Refer to Note 2).

8.Press the YES button and display “ / b = ”.

9.Rotate the lAMS L knob in the counterclockwise di- rection and find the focus bias value at which the C error rate becomes 220.

10.Press the YES button and display “ / c = ”.

11.Check that the C error rate is below 20 and ADER is 00. Then press the YES button.

12.	If the “(	” in “ -		- ( ” is above 20, press the			YES
	button.
	If below 20, press the				MENU/NO	button and repeat the
	adjustment from step 2.
13.	Press the	AEJECT	button to remove the test disc.

Note 1 : The relation between the C error and focus bias is as shown in the following figure. Find points a and b in the following figure using the above adjustment. The focal point position C is automatically calculated from points a and b.

Note 2 : As the C error rate changes, perform the adjustment using the average vale.

Cerror

220

b	c	a	Focus bias value
			(F. BIAS)

33