The laser power and gain
RF-amplifier is exposed both to work with
CD-ROM drive, ie with the disc, whose surface
has high reflectivity. Search
starts from the top of the lens, ie
when it is as close to the surface
If a CD is loaded, the focus will be successfully
found. In this case, the search focus is over, and
System Controller will determine the type of disc - CD.
If the loaded MD-disc, the focus will not be found, and
lens is moved to the original top
position and laser power and the coefficient
RF-amplifier gain set as for
with MD-disk. The next time you start searching
If the loaded MD-disc, the focus will be successfully
found, and the system controller determines the presence of
in the MD-CD player.
If the focus again will not be found, then the whole
procedure is repeated again. This whole cycle
will be repeated 4 times. After that, if the focus
and will not be found, the device will give the inscription "NO
In fact, the inscription "NO DISC" will appear first.
Since the system controller registers
number of turns the spindle-motor, and if the disc
not loaded, then after exceeding a certain
speed, the display shows "NO
The work of maintaining the nominal
laser power is similar to MZ-R50, which is used
the same optical unit - KMS-280A. Main
its difference from the one used in the MZ-R30
(KMS-250A), is the presence of the latter conclusion
RF modulator. At KMS-280A, this conclusion does not,
respectively, had no need for
external power supply connection of the modulator.
With regard to chain tracking and focus
tracking and speed disk, the player
MZ-R55 they work much the same as in MZ-R30/50.
It is only necessary to note that due to the presence
greater than MZ-R30/50 buffer memory,
eliminated the need to continuously read
information from the disk. In MZ-R30/50 read and write cycles
was 2 seconds (0.5 seconds reading or writing,
1.5 seconds pass). At the same servo
never switched off and continued to monitor the
focus, tracking and speed disk
even in between, when in fact no
happened to read or write. As has been
mentioned above, the MZ-R55 on battery power
disables the processor supply voltage to 2V
time, 37-39 seconds. Thus, the disabled
power driver. As a result, the disc
stops and reads or writes occur
out of or in the buffer memory. When powered from the mains
adapter power-off does not occur, but
processor still gives a command to shut down
tracking the focus and tracking, and servo
tracking speed translates into the so-
called coarse mode, in which
supported the frequency of rotation of the disk, but
Frame Synchronization is not carried out.
Chain of signal processing.
Differences in signal processing circuits between all
players are very small. In particular, all
players use the same type of RF-amplifier
- CXA2523, differing only in the letter index (-A
for the optical block KMS-230A and-AR for the optical
Block KMS-280A). Also differs only in letter
index used in iPods, chip DSP -
CXD2652 (respectively,-A and-AR). IC DAC / ADC
in fact one and the same: In MZ-R30/50 worth AK4515, and MZ-R55
- AK4517. The difference between them lies in the fact that
in the last integrated volume control,
control processor. In models where
applied AK4515 volume control - it
single chip. If the MZ-R30/50 for linear
outputs and a headphone used different
chips (a pair of operational amplifiers and LA4800V
respectively), the MZ-R55, these amplifiers
integrated with amplifiers for
headphones into a single chip AN75355A.
Major faults arising in
portable MiniDisc players.
The practice shows that the main
faults that occur in the portable
player associated with the optical block
mechanism for tracking devices, defect
PCB, the capture mechanism and drive
mechanical sensors. Optical assembly is
the most sensitive parts of a portable
player, because it is precision
Malfunction of the optical unit.
The main fault, which occurs with
optical unit as follows: impaired adjustment
optical system, broken, or modified
parameters (pollution-related) mechanisms
Suspension lens, lens contamination
lens or prism, the depletion of the laser.
First of all, make sure that
defect associated with the optical block. It is possible
guided by the following symptoms.
The disc is read properly, following the
The disc is normally read, but you can not record.
the disc to become clean (does not appear
Only the current record, but erased the previous
Record with a lot of mistakes.
Hypersensitivity to external shocks
If the player has one of the
the above-mentioned defects, it is necessary
go to the next validation.
The device is introduced into test mode. After
This device is translated into a search mode focus.
The objective lens of this should move up
and down evenly. Check with
power meter, laser radiation power.
It should be depending on the model order
0.85 mW. In addition, you have not
Is contaminated optics. After this it is necessary
transfer apparatus in the mode of the laser for
record. Power, which should show the device
should be about 6.8 mW. WARNING! Can not
keep the laser in the regime of emission of such a large
power for a long time (over 15s), so
as this may damage it. And the final
consists in the fact that the point at FOCUS ERROR
chip RF-amplifier (pin 34 on chip
CXA2523R) connects the oscilloscope to the device
inserted disc, and then he again transferred to the
Search mode focus. At the same time on the screen
oscilloscope should be observed a clear
symmetrical S-curve, after which the device
Tracking will make the capture and retention focus.
In the service center may be
Fixed problems related to pollution
lens or prism, if it is available.
If the measurement revealed that the power
laser radiation in read below
nominal or visually observed that the lens
contaminated, it is necessary to clean
laser unit. When cleaning the lenses need to
follow these simple requirements.
Use only the isopropyl alcohol with 100%
degree of purification. In no case be
apply any other alcohols and solvents
as you may receive the deposit or
microcracks on the surface of plastic lenses,
result begins to thicken optics.
Wipe clean with a need for a spiral, starting from the center
lens to the periphery with a cotton swab.
Push on the lens when it is necessary so that the
She went down to a few of his suspension.
Wipe with a two or three times, each time using
new tampon. After cleaning, you must again
check the power of radiation and to make sure that
She reached the nominal level.
If the S-curve is obtained by an asymmetric, then
necessary to change the optical block to a new,
because it means violation of the alignment
optics, which in a service center
can not be corrected.
After successful completion of such audits,
if it was still suspected defect
optical block, further testing can be
achieved only by replacing optobloka on
Fault tracking system.
Symptoms that indicate a fault
When you go to another track, the unit can not
find the point of beginning playback.
Unstable reading and writing. Usually
manifested either in the initial or on
Usually the problem is with the wear and tear
engine drive rotation or tracking
track. When playing a disc must
observe the RF-signal (pin 3 IC CXA2523R).
Jitter on the time axis (the so-called
jitter) indicates the unevenness of the rotation
spindle motor. In this case, it is necessary
replaced. Sometimes the problem is related to
desiccation or insufficient lubrication
on the worm gear from the engine monitoring
track of the optical unit. If lubrication
This site does not eliminate the defect, the motor
substitute a new one.
Defect of the PCB.
Symptoms suggestive of a defect of the PCB,
can be very diverse and not
The player is not included.
No entries from an external source.
Reacts to the jolting
Typically, most faults
related to the PCB, there is at
because not enough hard mount board in
places the external connectors. The result is not very
careful adherence to mate
jack is broken printed conductor
coming from the connector. Perhaps even breakage
some discrete elements located
on the board in the vicinity of the connector.
This is especially true for those MiniDisc
Players like MZ-R55, which is used
very thin printed circuit board and power supply
is like on the console board. In any
If there is any defect of this kind
recommended to duplicate the printed
wires running from the connector, with hinged
Besides the defect in the printed circuit board may be
associated with microcracks in the vias
and microcracks in the conductors. Checking
by tapping and weak
deformation of the PCB. Localize the
possible defect by using fast
local heating or cooling of the PCB
during its operation. Regularly pays not to be
respond to these actions. At detection
board space, where possible defect propaivayutsya
all vias and legs suspended
Defect capture mechanism and sensors.
Symptoms suggestive of a defect mechanism
capture drive and mechanical sensors.
Unexpected stop playback or
Hang the unit.
Not going to open the lid (you can not extract
Fault associated with the loading mechanism
disc occurs mainly due to its deformation.
It must be remembered that even a slight
deformation of the loading disk and can lead to
malfunction of the apparatus. In this case,
deformed part is changing. In some
severe cases have to change the whole
mechanism in the assembly.
Tips for tuning and repairing.
Setting power of the laser can be
take place in a test mode. Fulfill its need
simultaneously controlling the current through the laser
a voltmeter connected to the low-resistance
resistance (about 1Om) in the food chain laser
and the radiation power with a special
meter. You must first set
power required record 6.8 mW, current
consumption of the laser at the same time should not exceed
maximum value, which equals
rated plus 10%. Rated current
established for each optobloka
individually and written on its label. If
still have to establish a current in excess of
maximum value, then you can try
lower power rating at 10%, ie to 6,12 MW.
Again, the current should not exceed the maximum
values. If the current is still higher than it
value, we can assume that the laser lost
emission and optical block replaced by a new one. Not
should be placed above the current value of this
even in non-warranty cases, because
Otherwise, the laser when recording fast
exhausted and likely damage
Tracks that have been recorded before. When
measurement and adjustment of power
radiation of 6.8 mW laser is turned on, do not leave
more than 15 seconds. Besides, do not look at
the lens from a distance of less than 30cm.
Some problems can be identified simply
measuring the current consumption of the portable
player in different modes. For example,
when playing with power supply from
AC adapter current consumption is
approximately 180-200mA, if the player is in
stationary. If, during the
playing slightly to hit the player, then
current short-term should increase once a
2-3, which indicates that the servo start
search for the missing track. During recording
Current input pulses: 1.5 seconds and 180-200mA
0.5 seconds, 380-400mA (included in the laser mode
record). Increased power consumption in all
modes indicates that either the servo
work is unstable or defective one
components of the player. In the latter case it is easy
found at an elevated temperature of his body.
When you configure the servo is recommended
automatically set in each
Paragraph service menu. For the considered
players, this setting is done by clicking
pause button when the player is in
relevant paragraph in the service menu. Manual
infusion should be used in extreme
cases, the finding of a
When you replace the chip on the thin boards
For example, such as those used in the MZ-R55,
should be particularly careful, because
even a slight overheating of the board leads to its
deformation and unfit for further