Sony HCD-MD373 Checks Prior to Repairs, Temperature Compensation Offset Check, Laser Power Check

5-6. CHECKS PRIOR TO REPAIRS

These checks are performed before replacing parts according to “approximate specifications” to determine the faulty locations. For details, refer to “Checks Prior to Parts Replacement and Adjustments” (See page 13).

5-6-1. Temperature Compensation Offset Check

When performing adjustments, set the internal temperature and room temperature to 22 to 28°C.

Checking Procedure:

1.Press the =0/MD/CD/TUNING – button or )+/ MD/CD/TUNING + button to display “TEMP CHECK”.

2.Press the ENTER/YES “R” button.

3.“T=@@(##) [OK]” should be displayed. If “T=@@ (##) [NG]” is displayed, it means that the results are bad.

(@@ indicates the current value set, and ## indicates the value written in the non-volatile memory.)

5-6-2. Laser Power Check

Before checking, check the IOP value of the optical pick-up. (Refer to 5-8. Recording and Displaying IOP Information.)

Laser power meter

Optical pick-up objective lens

Digital volt meter

BD (MD) board

CN110 pin 5 (I+3V)

CN110 pin 4 (IOP)

Connection :

Checking Procedure:

1.Set the laser power meter on the objective lens of the optical pick-up. (When it cannot be set properly, press the =0/ MD/CD/TUNING – button or )+/MD/CD/TUNING +

button continuously to move the optical pick-up.)

Connect the digital volt meter to CN110 pin 5 (I+3V) and CN110 pin 4 (IOP).

2.Then, press the =0/MD/CD/TUNING – button or )+/MD/CD/TUNING + button and display “LDPWR CHECK”.

3.Press the ENTER/YES “R” button once and display “LD 0.9 mW $ ”. Check that the reading of the laser power meter be- come 0.84 to 0.92 mW.

4.Press the ENTER/YES “R” button once more and display “LD 7.0 mW $ ”. Check that the reading the laser power meter and digital volt meter satisfy the specified value.

Specified Value :

Laser power meter reading : 7.0 ± 0.2 mW

Digital voltmeter reading : Optical pick-up displayed value ± 10%

(Optical pick-up label)

KMS260A	(For details of the method for checking
27X40	this value, refer to “5-8. Recording and
	Displaying IOP Information”.)
B0825
N

Iop = 82.5 mA in this case

Iop (mA) = Digital voltmeter reading (mV)/1 (Ω)

5.Press the MENU/NO “R” button and display “LDPWR CHECK” and stop the laser emission.

(The MENU/NO “R” button is effective at all times to stop the laser emission.)

Note 1: After step 4, each time the ENTER/YES “R” button is pressed, the display will be switched between “LD 0.7 mW

$ ”, “LD 6.2 mW $ ”, and “LD WP $ ”. Nothing needs to be performed here.

5-6-3. Traverse Check

Connection :

Oscilloscope

BD (MD) board

CN110 pin 3 (TE)

CN110 pin 1 (VC)

V : 0.5 V/div

H : 10 ms/div

Input : DC mode

Checking Procedure:

1.Connect an oscilloscope to CN110 pin 3 (TE) and CN110 pin 1 (VC) of the BD (MD) board.

2.Load a disc (any available on the market). (Refer to Note 1.)

3.Press the )+/MD/CD/TUNING + button continuously and move the optical pick-up outside the pit.

4.Press the =0/MD/CD/TUNING – button or )+/ MD/CD/TUNING + button and display “EF MO CHECK”.

5. Press the ENTER/YES “R” button and display “EFB =	MO-
R”.

(Laser power READ power/Focus servo ON/tracking servo OFF/ spindle (S) servo ON)

6.Observe the waveform of the oscilloscope, and check that the specified value is satisfied. Do not press the =0/MD/CD/

TUNING – button or)+/MD/CD/TUNING + button. (Read power traverse checking)

(Traverse Waveform)

A

VC

B

Specified value : Below 10% offset value
Offset value (%) = IA – BI X 100
2 (A + B)
7. Press the ENTER/YES “R” button and display “EFB =	MO-
W”.

8.Observe the waveform of the oscilloscope, and check that the specified value is satisfied. Do not press the =0/MD/CD/

TUNING – button or)+/MD/CD/TUNING + button. (Write power traverse checking)

(Traverse Waveform)

A

VC

B

Specified value : Below 10% offset value

Offset value (%) = IA – BI X 100 2 (A + B)

33