Electrical Adjustment - Kenwood RD-M52MD Service Manual

RD-M52MD/M72MD

7. Electrical adjustment

7-1 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.
7-2 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 insert-
ing the connector. Moreover, take careful measures
against electrostatic destruction. The flexible board is cut
easily. Handle the flexible board with care.
7-3 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.
1.Temperature compen-
sation offset adjustment
2.Laser power adjustment
3.Traverse adjustment
4.Focus bias adjustment
5.Error rate confirmation
2) In the test mode, perform the adjustment. After adjust-
ment is completed, cancel the test mode.
3) Perform the adjustment in the order described.
4) Use the following tools and measurement equipment.
• CD test disc TGYS-1
• Laser power meter
• Oscilloscope (with bandwidth of more than 40 MΩ)
(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 moni-
tored on the oscilloscope. (VC and GND are short-circuit-
ed in this case.)
7-4 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 6-7.
8
CIRCUIT DESCRIPTION
Pick-up
Flexible board
Laser tap
Optical BD board
pick-up IC6 D101 IC1,IC2,IC10
X O O
O O X
O O X
O O X
O O X
7-5 Offset Adjustment
Key
No.
1 Volume/multi-control Select [TEMP ADJU]
2 PLAY
3 Volume/multi-control Input "yy" with present temp..
4 PLAY
7-6 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 digital voltmeter 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
Objective lens of
optical pick up
1. Laser Power Adjustment
No. Key
1 Volume/
multi-control
2
PLAY
O
3 EJECT
O
4 4/¢
O
O
5 Volume/
multi-control Adjust "xx" so that the power meter shows 0.9mW.
O
6 PLAY
7 Volume/
multi-control
8 PLAY
Start from No.2 if readjust.
2. Laser Power Check
No.
1 Volume/multi-control [LDPWR CHEC]
2 PLAY
3 PLAY
(optical pick-up label)
Display/Function
[TEMP=xx (yy)]
(xx=compensation data, yy=setting temperature)
[TEMP= SA]
[TEMP ADJU] in writing data
Laser
power meter
Digital
voltmeter
X33
ADJUSTMENT
IOP2
IOP1
Display/Function
[LDPWR ADJU]
Load recordable disc
Load the disc and lazer on
[(0.9mW) $xx] read power
(xx=power value)
Unload the disc and laser on
Move the pickup to check the laser power with
laser power meter sensor
[(7.0mW) $xx] writing power
Adjust "xx" so that the power meter shows 7.0mW.
This adjustment should be carried out in 15 secs.
Laser power off
Display shows [LDPWR ADJU] after [LDPWR<$xx]
to save the data in E2PROM
Key Display/Function
[(0.9mW) $xx]
(xx=0.85 to 0.95mW)
[(7.0mW) $xx]
Laser power meter: 7.0+-1.0mW
VOM:optical pickup indication value +-10%
KMS 260B
27x40
B0825
In this case, lop = 82.5 mA
lop(mA) = Reading of digital voltmeter(mV)/1(Ω)
+
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