Sony MDS-PC2 service manual Focus Bias Adjustment, Adjusting Procedure

11.Press the =, + buttons until the waveform of the oscil- loscope 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 ^ “PROGRAM” button, and save the adjustment

results in the non-volatile memory. (“EFB = SAVE” will be displayed for a moment.)

Next “EF MO ADJUST” is displayed. The disc stops rotating automatically.

13.Press the 6 (EJECT) button and remove the disc.

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

15.Press + button and display “EF CD ADJUST”.

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

17.Press the = , + buttons 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 ^“PROGRAM” button, display “EFB =	SAVE”

for a moment and save the adjustment results in the non-vola- tile memory.

Next “EF CD ADJUST” will be displayed.

19.Press the 6(EJECT) 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

CN110 pin 3 (TE)		10pF
CN110 pin 1	(VC)

5-12. FOCUS BIAS ADJUSTMENT

Adjusting Procedure :

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

2.Press the + button and display “CPLAY MODE”.

3.Press the ^“PROGRAM” button and display “CPLAY MID”.

4.	Press the	p“PROGRAM”			button when “C1 =		AD =	”
	is displayed.
5.	Press the			button and display “FBIAS ADJUST”.
		+
6.	Press the					button and display “	/	a =
			p “PROGRAM”
	”.
	The first four digits indicate the C1 error rate, the two digits
	after “/” indicate ADER, and the 2 digits after [a =] indicate the
	focus bias value.

7.Press the + button and find the focus bias value at which the C1 error rate becomes about 200 (Refer to Note 2).

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

9.Press the = button direction and find the focus bias value at which the C1 error rate becomes about 200.

10.	Press the	^“PROGRAM”			button and display “			/	c =
	”.
11.	Check that the C1 error rate is below 50 and ADER is 00. Then
	press the	^ “PROGRAM”				button.
12.	If the “(	)” in “ -		- ( )” is above 20, press the					p
	“PROGRAM”		button.
	If below 20, press the			p “PROGRAM”			button and repeat the
	adjustment from step 2.
13.	Press the	6(EJECT)		button to remove the test disc.

Note 1 : The relation between the C1 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 C1 error rate changes, perform the adjustment us- ing the average vale.

C1 error

about 200

b	c	a	Focus bias value
			(F. BIAS)

27