Sony HCD-MD373 service manual Focus Bias Adjustment, Press the ENTER/YES R button, display EFB =

9.Press the ENTER/YES “R” button, and save the adjustment

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

10.“EFB = MO-P”. will be displayed.

The optical pick-up moves to the pit area automatically and servo is imposed.

11.Press the =0/MD/CD/TUNING – button or)+/ MD/CD/TUNING + button until the waveform of the oscillo-

scope 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 ENTER/YES “R” 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 (MD) button and remove the disc.

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

15.Press the =0/MD/CD/TUNING – button or)+/ MD/CD/TUNING + button and display “EF CD ADJUST”.

16. Press the ENTER/YES “R” button and display “EFB =

CD”. Servo is imposed automatically.

17.Press the =0/MD/CD/TUNING – button or)+/ MD/CD/TUNING + button so that 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
18. Press the ENTER/YES “R” 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 (MD) 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

5-12. FOCUS BIAS ADJUSTMENT

Adjusting Procedure :

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

2.Press the =0/MD/CD/TUNING – button or )+/ MD/CD/TUNING + button and display “CPLAY MODE”.

3.Press the ENTER/YES “R” button and display “CPLAY MID”.

4. Press the	MENU/NO “R”	button when “C1 =	AD = ”
is displayed.

5.Press the =0/MD/CD/TUNING – button or )+/ MD/CD/TUNING + button and display “FBIAS ADJUS”.

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

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 )+/MD/CD/TUNING + button and find the focus bias value at which the C1 error rate becomes about 200

(Refer to Note 2).
8. Press the	ENTER/YES “R”	button and display “	/ b =
”.

9.Press the =0/MD/CD/TUNING – button and find the focus bias value at which the C1 error rate becomes about 200.

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

11.Check that the C1 error rate is below 50 and ADER is 00. Then press the ENTER/YES “R” button.

12.If the “( ” in “ - - (” is above 20, press the ENTER/ YES “R” button.

If below 20, press the MENU/NO“R” button and repeat the adjustment from step 2.

13.Press the 6(MD) 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)

BD (MD) board 330 kΩ

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

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