DM-VH7
CIRCUIT DESCRIPTION
9
6. Electrical adjustment
6-1 Precaution during confirmation of Laser Diode
emission
During adjustment, do not view the emission of a laser
diode from just above for confirmation. This may damage
your eyes.
6-2 Precaution on handling of Optical pick-up
(KMS-260B)
The laser diode in an optical pick-up is easy to be subject
to electrostatic destruction. Therefore, solder-bridge the
laser tap on the flexible board when handling the optical
pick-up.
When removing the flexible board from the connector,
make a solder bridge in advance, then remove the board.
Be careful not to remove the solder bridge before
inserting the connector. Moreover, take careful
measures against electrostatic destruction. The flexible
board is cut easily. Handle the flexible board with care.
6-3 Precaution during adjustment
1) Perform the adjustment and confirmation marked with “O”
in the order shown in the table when the parts below are
replaced.
2) In the test mode, perform the adjustment. After
adjustment is completed, cancel the test mode.
• CD test disc TGYS-1
• Laser power meter
• Oscilloscope (with bandwidth of more than 40 M
Ω
)
(Calibrate the probe before measurement.)
• Digital voltmeter
• Thermometer
5) Take care that VC and GND (ground) are not connected
on the oscilloscope when two or more signals are
monitored on the oscilloscope. (VC and GND are short-
circuited in this case.)
6-4 Creating the recordable continuous recording
disc
This disc is used for focus bias adjustment and error rate
confirmation. How to create the recordable continuous
recording disc is 5-6.
Optical
BD board
pick-up
IC6
D101
IC1,IC2,IC10
1.Temperature compen-
sation offset adjustment
X
O
O
O
2.Laser power adjustment
O
O
X
O
3.Traverse adjustment
O
O
X
O
4.Focus bias adjustment
O
O
X
O
5.Error rate confirmation
O
O
X
O
Pick-up
Flexible board
Laser tap
6-5 Offset Adjustmen
N o .
K e y
D i s p l a y / F u n c t i o n
1 UP/DOWN
Select [TEMP ADJUST]
2 PLAY
[TEMP=xx (yy)]
(xx=compensation data, yy=setting temperature)
3 UP/DOWN
Input "yy" with present temp..
4 PLAY [TEMP=
✽✽
SAVE]
[TEMP ADJUST] in writing data
6-6 Laser Power Check and Adjustment
Laser power setting in playback and recording modes.
Preparation
1. Remove the MD mechanism from the unit.
2. Connect the VOM to IOP1 and 2 on X33 pcb.
3. Remove the top plate from traverse unit.
4. Remove the magnetic head.
5. Remount the MD mechanism to the unit
+
-
Laser
power meter
Digital
voltmeter
Objective lens of
optical pick up
IOP2
IOP1
X33
ADJUSTMENT
1. Laser Power Adjustment
N o .
K e y
D i s p l a y / F u n c t i o n
1 UP/DOWN [LDPWR ADJUST]
Load recordable disc
2
Load the disc and lazer on
[(0.9mW) $xx] read power
(xx=power value)
3 EJECT
Unload the disc and laser on
4 FF/FB
Move the pickup to check the laser power with
laser power meter sensor
(REC)
(Press the REC key if the pickup is in the proper position)
5 UP/DOWN Adjust "xx" so that the power meter shows 0.9mW.
6 PLAY
[(7.0mW) $xx] writing power
7 UP/DOWN Adjust "xx" so that the power meter shows 7.0mW.
This adjustment should be carried out in 15 secs.
8 PLAY
Laser power off
Display shows [LDPWR ADJUST] after [LDPWR<$xx]
to save the data in E2PROM
Start from No.2 if readjust.
2. Laser Power Check
N o .
K e y
D i s p l a y / F u n c t i o n
1 UP
[LDPWR CHECK]
2 PLAY
[(0.9mW) $xx]
(xx=0.85 to 0.95mW)
3 PLAY
[(7.0mW) $xx]
Laser power meter: 7.0+-1.0mW
✽
VOM:optical pickup indication value +-10%
✽
In this case, lop = 82.5 mA
lop(mA) = Reading of digital voltmeter(mV)/1(
Ω
)
(optical pick-up label)
KMS
260B
27x40
B0825
1p
99.10.29
3:45
PM
y [ W 6
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