Advertisement
Maintenance of MD pickup
1. Cleaning of pickup lens
(1) Prior to changing the pickup, clean the pickup lens.
(2) For cleaning the lens, use the following cotton swab after
mearsing it in alcohol.
Product No. JCB-B4; Manufacturer;Nippon Cotton Swab
2. Confirmation of the service life of laser
diode when the service life of the laser
diode has been exhausted, the following
symptoms will appear.
(1) Recording will become impossible.
(2) The RF output (EFM output and eye pattern amplitude)
will become lower.
(3) The drive current required for light emitting of laser diode
will be increased.
Confirm the service life according to the following flow chart:
Is the recording power
(6.23mV) output with the
laser power under
test mode?
YES
Is the drive current
of laser diode
120mA or less?
YES
OK.
3. Method of measuring the drive current of
laser diode
For disk check after the laser power adjustment, be
sure to use a disk that is not only clean without
scratch but full of circular recording, because the
adjustment is automatically carried out and resultant
setup values are written in the memory.
NO
Change the pickup
NO
Change the pickup
Procedures of changing
the MD pickup
Change the MD pickup by referring
to "Removing the MD pickup" in the
Disassembly Method.
Set the pickup to [TEST] mode according
to the procedures described in the
Adjustment Method.
Adjust the laser power.
Completion the disc.
Completion of changing the MD pickup.
[Caution]
Since this system is designed to perform
magnetic recording, the laser power ten
times or over of the conventional MD player
will be output. Therefore, be sure to perform
not only adjustment and operation of this
system so carefully as not to directly look at
the laser beam or touch on the body.
Measure the voltage at both sides of R337 on
the MD servo control P.C. board. If the voltage
is 120 mV or more, the laser diode is judged
as it has come to the end of its service life.
4. Semi-solid state resistors on
the APC P.C. board
The semi-solid state resistor on the APC P.C.board
attached to the pickup is used for adjusting the laser
power. Since these resistor should be adjusted in
pair according to the characteristics of the optical
block, be sure not to touch on the resistors.
Since the service life of the laser diode will be
exhausted when the laser power is low, it is
necessary to change the pickup. Meanwhile, do not
pickup. Otherwise, the pickup will be damaged due
to over current.
UX-F70MD/UX-F72MD
1-43
Advertisement
