Sony PMC-MD55 Service Manual page 22

2. PRECAUTIONS FOR CHECKING LASER DIODE
EMISSION
To check the emission of the laser diode during adjustments, never
view directly from the top as this may lose your eye-sight.
3. PRECAUTIONS FOR USE OF OPTICAL
PICK-UP (KMS-260A)
As the laser diode in the optical pick-up is easily damaged by static
electricity, solder the laser tap of the flexible board when using it.
Before disconnecting the connector, desolder first. Before con-
necting the connector, be careful not to remove the solder. Also
take adequate measures to prevent damage by static electricity.
Handle the flexible board with care as it breaks easily.
pick-up
Optical pick-up flexible board
4. PRECAUTIONS FOR ADJUSTMENTS
1. When replacing the following parts, perform the adjustments
and checks with ¬ in the order shown in the following table.
Optical
Pick-up
1. Temperature
G
compensation
offset adjustment
2. Laser power
¬
adjustment
3. EF balance
¬
adjustment
4. Focus bias
¬
adjustment
¬
5. Error rate check
2. Set the test mode when performing adjustments.
After completing the adjustments, release the test mode.
Perform the adjustments and checks in "group S" of the test
mode.
3. Perform the adjustments to be needed in the order shown.
flexible board
laser tap
BD Board
IC171 IC101, IC121
D101
¬ ¬ G
¬ G ¬
¬ G ¬
¬ G ¬
¬ G ¬
4. Use the following tools and measuring devices.
• Check Disc (MD) TDYS-1
(Part No. 4-963-646-01)
• Test Disc (MDW-74/AU-1) (Part No. 8-892-341-41)
• Laser power meter LPM-8001 (Part No. J-2501-046-A)
or MD Laser power meter 8010S (Part No. J-2501-145-A)
• Oscilloscope (Measure after performing CAL of prove)
• Digital voltmeter
• Thermometer
• Jig for checking BD board waveform
(Part No. : J-2501-149-A)
5. When observing several signals on the oscilloscope, etc.,
make sure that VC and ground do not connect inside the oscil-
loscope.
(VC and ground will become short-circuited)
6. Using the above jig enables the waveform to be checked with-
out the need to solder.
(Refer to Servicing Notes on page 4)
7. As the disc used will affect the adjustment results, make sure
that no dusts nor fingerprints are attached to it.
Laser power meter
When performing laser power checks and adjustment (electrical
adjustment), use of the new MD laser power meter 8010S (Part
No. J-2501-145-A) instead of the conventional laser power meter
is convenient.
It sharply reduces the time and trouble to set the laser power meter
sensor onto the objective lens of optical pick-up.
5. CREATING CONTINUOUSLY-RECORDED DISC
* This disc is used in focus bias adjustment and error rate check.
The following describes how to create a continuous recording
disc.
IC192
1. Insert a disc (blank disc) commercially available.
2. Turn the JOG dial and display "CREC MODE".
G
[YES, ENTER]
3. Press the
Display "CREC (0300)" and start to recording.
4. Complete recording within 5 minutes.
¬
[NO, CANCEL]
5. Press the
[MD EJECT ]
6. Press the
G
The above has been how to create a continuous recorded data for
the focus bias adjustment/check and MO error rate check.
G
Note :
• Be careful not to apply vibration during continuous recording.
G
– 22 –
button again to display "CREC MID".
button and stop recording .
6
button and remove the disc.