Schematic diagram of a dvd rw drive. CD player repair. It's simple! The most common causes of drive failure

CD-ROM drive device.

A CD-ROM drive is a complex electronic-optical-mechanical device for reading information from laser disks. A typical drive consists of an electronics board (sometimes two or even three boards - a spindle control circuit and an opto-receiver amplifier separately), a spindle assembly, an optical read head with a drive for its movement and disk loading mechanics.

The electronics board contains:

circuit for amplification and correction of the signal from the optical head;
PLL signal circuits and spindle ACS;
Reed-Solomon code processor;
ACS schemes for beam focusing and dynamic track tracking;
control circuit for moving the optical head;
control processor (logic);
buffer memory;
interface with controller (IDE/SCSI/others);
interface and output connectors sound signal;
block of mode switches (jumpers/jumpers).

A typical drive consists of an electronics board, a spindle motor, an optical read head system and a disk loading system. The electronics board contains all the drive control circuits, the interface with the computer controller, the interface connectors and the audio signal output. Most drives use one electronics board, but in some models separate circuits are placed on small auxiliary boards.

Spindle assembly (the motor and the spindle itself with the disk holder) are used to rotate the disk. Typically the disk rotates at a constant linear speed, which means that the spindle changes speed depending on the radius of the track from which the optical head is currently reading information. As the head moves from the outer radius of the disk to the inner radius, the disk must quickly increase its rotational speed by approximately doubling, so good dynamic response is required from the spindle motor. The motor is used for both acceleration and deceleration of the disk.

The spindle itself is fixed to the axis of the spindle motor (or in its own bearings), to which the disk is pressed after loading. The surface of the spindle is sometimes covered with rubber or soft plastic to prevent the disc from slipping, although in more advanced designs only the upper clamp is rubberized to increase the accuracy of the disc being installed on the spindle. The disk is pressed against the spindle using the upper clamp located on the other side of the disk. In some designs, the spindle and clamp contain permanent magnets, the attractive force of which forces the clamp through the disk to the spindle. Other designs use coil or flat springs for this purpose.

Optical head system consists of the head itself and its movement system. The head contains a laser emitter based on an infrared laser LED, a focusing system, a photodetector and a pre-amplifier. Focusing system It is a movable lens driven by an electromagnetic voice coil system, similar to the movable loudspeaker system. Change in tension magnetic field cause the lens to move and refocus the laser beam. Thanks to its low inertia, such a system effectively tracks the vertical runout of the disk even at significant rotation speeds.

Head movement system has its own drive motor, which drives the carriage with the optical head using a gear or worm gear. To eliminate backlash, a connection with an initial voltage is used: with a worm gear - spring-loaded balls, with a gear - pairs of gears spring-loaded in opposite directions. The motor used is usually a stepper motor, and much less often a brushed DC motor.

Disc loading system There are three options: using a special cassette for the disk (caddy), inserted into the receiving niche of the drive (similar to how a 3" floppy disk is inserted into the drive), using a retractable tray (tray), on which the disk itself is placed, and using a retractable mechanism. Systems with Tray usually contain a special motor that allows the tray to extend, although there are designs (for example, Sony CDU31) without a special drive that are pushed in by hand. Systems with a retracting mechanism are usually used in compact CD-Changers for 4-5 discs, and necessarily contain a motor for drawing in and ejecting disks through a narrow charging slot.

On the front panel The drive usually contains an Eject button for loading/unloading a disc, a drive access indicator, and a headphone jack with an electronic or mechanical volume control. A number of models have added a Play/Next button to start playing audio discs and switch between audio tracks.

Most drives also have a small hole on the front panel for emergency removal of the drive in cases where in the usual way this cannot be done - for example, if the tray drive or the entire CD-ROM fails, if there is a power failure, etc. You usually need to insert a pin or a straightened paper clip into the hole and gently press - this unlocks the tray or disk case, and it can be pulled out manually (although there are drives, for example Hitachi, in which you need to insert a small screwdriver into such a hole and rotate it located behind the front drive panel axle with slot).

CD-ROM block diagram

Functional diagram of CD-ROM

A very important component of the device is the optical-electronic information reading system. Despite its small size, this system is a very complex and precise optical device.

It consists of:

servo disk rotation control systems;
Servo positioning systems for laser reading devices;
servo autofocus systems; radial tracking servo system;
reading systems;
laser diode control circuits.

The servo disk rotation control system ensures the constant linear speed of the reading track on the disk relative to the laser spot. In this case, the angular speed of disk rotation depends both on the distance of the reading head to the center of the disk, and on the conditions for reading information.

The servo system for positioning the information reading head ensures a smooth approach of the head to a given recording track with an error not exceeding half the track width in the search modes for the required piece of information and normal playback. The reading head, and with it the laser beam, moves across the disk field by the head motor. Engine operation is controlled by forward and reverse motion signals from the control processor, as well as signals generated by the radial error processor.

The radial tracking servo system keeps the laser beam on the track and optimal conditions reading information. The system operates based on the three light spot method. The essence of the method is to split the main laser beam using diffraction grating into three separate beams with slight divergence. The central light spot is used for reading information and for operating the autofocus system. Two side beams are located in front and behind the main beam with a slight offset to the right and left. The mismatch signal of these beams from the positioning sensors affects the tracking drive, causing, if necessary, correction of the position of the central beam.

The performance of the radial tracking system can be monitored by changes in the error signal supplied to the tracking drive.

Monitoring and control of the vertical movement of the focusing lens is carried out under the influence of servofocus. This system ensures precise focusing of the laser beam while working on the working surface of the disk. After loading and starting the CD, focus adjustment begins based on the maximum level of the output signal of the photodetector matrix and minimum level error signal of fine focusing detectors and zero focus passing. At the moment the disc starts, the CD-ROM control processor generates correction signals that provide multiple (double or triple) movement of the focal lens necessary to accurately focus the beam on the disc track. When focus is found, a signal is generated that allows information to be read. If after two or three attempts this signal does not appear, the control processor turns off all systems and the disk stops. Thus, the performance of the focusing system can be judged both by the characteristic movements of the focal lens at the moment the disk starts, and by the signal that starts the disk acceleration mode when the focus of the laser beam is found.

The information reading system contains a photodetector matrix and differential signal amplifiers. The normal operation of this system can be judged by the presence of high-frequency signals at its output when the disk rotates.

The laser diode control system provides the rated excitation current of the diode in the disk starting and information reading modes. A sign of normal operation of the system is the presence of an RF signal with an amplitude of about 1 V at the output of the reading system.

Systems for recording, reading and subsequent processing of information determine the general functional diagram of a CD-ROM, presented in the functional diagram. In addition to the systems discussed above, it includes a clock generator that provides clock signals to all CD-ROM nodes, and an EFM demodulator that converts 14-bit code messages from the disk into 8-bit serial code. Next, the information enters the digital data processor, which, together with the system control processor, is the heart of the entire device. This is where data deinterleaving and error correction occurs. The task of data interleaving when recording information is to “stretch” each byte of information over several recording frames. Moreover, if even a few frames of information are lost as a result of mechanical damage to the disk surface, the result of reverse data interleaving will be the presence of small errors in individual bytes. Such errors are corrected by an error correction circuit.

A laser head (LH) is used to read information from a CD. The LG housing contains a laser diode, an internal optical system (diffraction grating, cylindrical, collimator and other lenses, prism), focusing and tracking coils with a focusing lens, and a laser diode (Fig. 1.1).

Rice. 1.1. Laser head design

When the supply voltage is applied, a semiconductor laser diode generates a coherent (wave phase difference is constant over time) beam, which is divided into a main beam and two additional beams using a diffraction grating. Having passed through the elements of the optical system and the focusing lens, these rays fall on the compact disc (Fig. 1.2).

Rice. 1.2. Focusing the beam on the disk surface

The precise focusing of the rays on the disk is carried out by focusing coils that set the desired position of the lens. After being reflected from the disk, the rays again fall on the focusing lens and further into the optical system. In this case, reflected rays are separated from incident ones due to their different polarization. Before hitting the photo sensors (photodiode array), the main beam passes through a cylindrical lens, which uses the distortion effect to determine focusing accuracy (Fig. 1.3).

Rice. 1.3. Beams and signals on photodetectors

If the beam is focused exactly on the surface of the CD, the reflected beam at the photo sensors has the shape of a circle; if in front of or behind the surface, it has the shape of an ellipse.

The signals from the photo sensors are pre-amplified, and the difference between the signals (A+C) and (B+D) determines the focusing error FE (Focus Error). With precise focusing, the FE signal is zero.

Two side beams fall on sensors E and F. They are used to track the passage of the main beam along the read path (track) (Fig. 1.4).

Rice. 1.4. Track tracking principle: a). precise passage of the beam along the track; b). erroneous

The difference between the E and F signals determines the tracking error TE (Tracking Error).

The combined signal from sensors A, B, C and D is a high frequency (RF) signal (>4 MHz) in EFM (Eight-to-Fourteen Modulation) format. It contains encoded audio information and additional data.

1.2 Operation of servo circuits and main signals during disk reading

When inserting a CD, the Slide motor moves the laser head to its home position until the "Head Home Position" limit switch closes. (In some models, there are not two, but one motor for moving the carriage and positioning.) Then the head begins to slowly move away until the limit switch opens.

By LDON signal laser automatic power servo circuit(ALPC - Automatic Laser Power Control) supplies power to the laser diode. Sometimes additional limit switches can be used to block the laser from turning on and prevent the laser beam from entering the eyes when the mechanism is disassembled, and sometimes the laser is constantly turned on when the carriage is closed. The ALPC system maintains the laser diode output power at a specified level. The current radiation power is controlled by a photodetector placed in the same housing with the laser diode.

The servo processor begins to generate initial focus search (FSR) pulses, which are sent to focusing servo circuits and then through the driver - to the focusing lens. The focusing servo circuit is designed to compensate for CD beats (up and down). The driver (output stage) is used to amplify the power of the signals. The lens begins to move up and down. When the beam is accurately focused on the surface of the CD, the focusing error signal FE=(A+C)-(B+D) will become minimal, the FSR pulses will be turned off, and the focusing servo circuit will begin to control the focusing coil using the FEM signal, which is the corrected signal F.E. After successful focusing, the FOK (FocusOk) signal is generated. If after 3-4 FSR pulses the FOK signal is not generated, then the absence of a CD is detected and the player stops operating.

The FOK signal goes to servo circuits for controlling engine speed(SUSVD). They produce signals MON (enable), MDS (speed), MDP (phase), CLV (control) to control the operation of the engine and regulate its rotation speed. The engine begins to rotate and pick up speed. In some players, engine start pulses are generated before the FOK signal is applied, along with FSR pulses. At a constant angular speed of rotation from the beginning to the end of the disk, the track diameter and linear speed increase. SUSVD maintains the linear speed of disk rotation at a constant level, and after stopping the player, it slows down the engine speed.

The nominal flow rate of information read from the disk is 4.3218 Mbit/s.

At the same time, the FOK signal is sent to tracking servo circuit and activates its work. This servo circuit ensures that the beam passes precisely to the center of the track. A tracking error signal (TE=E-F) is used to track the beam position. The filtered high-frequency component of the TE signal (TER signal) is fed to the tracking coil. The tracking coil moves the lens in a direction perpendicular to the tracks and can provide reading of up to 20 tracks without moving the LG. The filtered low-frequency component of the TE signal (RAD signal) is fed to a positioning motor, which moves the LG across the disk field. The laser head moves periodically when the number of tracks read is outside the limits allowed by the tracking coil.

Tracking circuits cannot independently determine whether a beam is on or between an information track. For this, a mirror detector is used, which, based on the amplitude of the high-frequency EFM signal, determines the position of the beam and corrects it. If the beam is between the tracks, then the amplitude of the EFM signal is minimal. If tracking is successful, the tracking servo circuits generate a TOK (Tracking OK) signal.

After this, reading information from the disk begins. Clocked by pulses from a quartz oscillator, PLL detector adjusts in frequency and phase to the high-frequency EFM signal and extracts data from it. A shift register converts serial data into parallel data. Then the information is decoded, undergoes initial processing (deinterleaving, error correction, etc.) and is placed in a “half-state” buffer. SUSVD maintains buffer fill at 50%. If the rotation speed is low and the buffer is less than 50% full, the servo circuit will increase the engine speed, and vice versa. You can slow down the disc for a while, but the sound will not be interrupted. This is due to the presence of a buffer. The principle of operation is similar in AntiShock circuits, but they have a higher capacity and filling percentage.

Information is written and read into the buffer using the WFCK and RFCK pulses, respectively. The read information is divided into audio data and subcode. Subcode is service information that contains synchronizing bits, information about the current track, and time. Subcodes use servo circuits to position the laser head to the desired location. The subcode bitrate is 58.8 kbps. The audio data is processed in audio circuits and an analog audio signal is output.

1.3 Sound conversion

The conversion of audio from digital to analog format occurs in the audio circuits. Initially, the left and right channel data are mixed (multiplexed) and placed on the same stream. The audio data undergoes further processing (interpolation, substitution) in digital audio circuits.

Digital filters and accelerated sampling circuits (OVERSAMPLING) can be used to improve sound quality and reduce noise. Digital filters convert the audio signal from 16 to 18 or 20 bits, reducing the quantization step in the output signal. When using an 18-bit filter and a DAC, the step is reduced by a factor of 4 and, accordingly, the sound becomes more pleasant. Fast sampling circuits move quantization noise (>22 kHz) to higher frequencies. Data for the DAC is read and converted at 2, 4, 8 or 16 times the rated speed.

The DAC converts digital signals into analog form. There are two options (Fig. 1.5).

Rice. 1.5. Enabling DACs in Audio Circuits

Expensive models use the option shown in Fig. 1.5, a. The multiplexed digital signal is fed to a demultiplexer, which, based on timing pulses, divides it into 2 digital streams, respectively, for the left and right channels. Each channel uses its own DAC. In another option (Fig. 1.5,b), one DAC is used, the analog signal from which is divided into two channels by the switch. In both cases, a delay line is used to time align the right and left channel data.

Audio signals from the DAC output are amplified and fed to the output filters. Filters cut high-frequency components (>20 kHz), quantization noise and smooth out the step.

Audio circuits use transistor switches that are controlled by a MUTE signal and short-circuit the output signal to the chassis. If the disc is read normally, then in the “Playback” or “Rewind by Track” modes, the processor disables sound blocking. In all other modes the MUTE function is activated.

The quality of the audio signal directly depends on the quality of the filter. Expensive models use higher order filters.

1.4 Operation of the player in various modes

1.4.1 Loading a disc

When the player is connected to the network, a Reset signal is generated, which resets the processor registers. The processor checks the position of the carriage, the laser head (if necessary, positions it in the initial position) and the presence of a CD. On some models, when a disc is present, the player enters playback mode.

When you press the "Open/Close" key, the processor sends a signal to the carriage motor, the carriage moves out. When the carriage moves out completely, the “Final position of the carriage” limit switch is triggered and the processor stops the engine. Some turntable models use electrical circuits without limit switches, which, based on the current consumed by the motor, determine the initial and final positions of the carriage.

The disk is installed in the carriage. When the "Open/Close" key is pressed again, the processor starts the engine. The carriage moves in until the “Initial position of the carriage” limit switch is triggered. The disk is placed on the table and pressed against it. The player is trying to read the disc title.

Information from the disk is read from the center. The title is physically located at the beginning of the CD. It contains information about the number of songs, total time, etc. If the information is considered successful, the disk characteristics will be displayed on the screen. Otherwise, "Error", "No Disc" or "-" will appear on the display and, on some models, playback mode will be locked.

1.4.2 Playback

The LG begins to read the disc, looks for the beginning of the first track and begins to play it. The track number and time are simultaneously displayed on the display.

1.4.3 Pause

Disc playback pauses. Audio output is blocked. The laser head remains in one place.

1.4.4 Rewind by tracks "<<",">>"

LG looks for the beginning of the desired track and begins to play it.

1.4.5 Rewind by track "<", ">

In this mode, the track is played quickly. The processor produces JF (jump forward) and JP (jump backward) signals. The tracking coil and LG slowly move forward (backward). The read beam constantly jumps from the current track to the next one. Using a detector, the number of crossed paths is counted. Accordingly, a signal is generated to control the tracking coil (up to 25 tracks) and the positioning motor. The amplitude of the audio output signal is slightly reduced.

Laboratory work No. 4

Topic: Disk drive (drive)

Goal: To know the insides of the drive, how it works, DVD discs.

Explanation of the work.

CD-ROM drive device.

A typical drive consists of an electronics board, a spindle motor, an optical readhead system, and a disk loading system. The electronics board contains all the drive control circuits, the interface with the computer controller, the interface connectors and the audio signal output. Most drives use a single electronics board, but some models have separate circuits on small auxiliary boards.

Spindle assembly (the motor and the spindle itself with the disk holder) are used to rotate the disk. Typically the disk rotates at a constant linear speed, which means that the spindle changes speed depending on the radius of the track from which the optical head is currently reading information. As the head moves from the outer radius of the disk to the inner radius, the disk must quickly increase its rotational speed by approximately doubling, so good dynamic response is required from the spindle motor. The motor is used for both acceleration and deceleration of the disk.

Optical head system consists of the head itself and its movement system. The head contains a laser emitter based on an infrared laser LED, a focusing system, a photodetector and a pre-amplifier. Focusing system It is a movable lens driven by an electromagnetic voice coil system, similar to the movable loudspeaker system. Changes in the magnetic field strength cause the lens to move and the laser beam to refocus. Thanks to its low inertia, such a system effectively tracks the vertical runout of the disk even at significant rotation speeds.

Head movement system has its own drive motor, which drives the carriage with the optical head using a gear or worm gear. To eliminate backlash, a connection with an initial voltage is used: with a worm gear - spring-loaded balls, with a gear - pairs of gears spring-loaded in opposite directions. The motor used is usually a stepper motor, and much less often a brushed DC motor.

Disc loading system There are three options: using a special cassette for the disk (caddy), inserted into the receiving niche of the drive (similar to how a 3" floppy disk is inserted into the drive), using a retractable tray (tray), on which the disk itself is placed, and using a retractable mechanism. Systems with Tray usually contain a special motor that allows the tray to extend, although there are designs (for example, Sony CDU31) without a special drive that are pushed in by hand. Systems with a retracting mechanism are usually used in compact CD-Changers for 4-5 discs, and necessarily contain a motor for drawing in and ejecting disks through a narrow charging slot.

On the front panel The drive usually contains an Eject button for loading/unloading a disc, a drive access indicator, and a headphone jack with an electronic or mechanical volume control. A number of models have added a Play/Next button to start playing audio discs and switch between audio tracks.

Most drives also have a small hole on the front panel designed for emergency removal of the disk in cases where this cannot be done in the usual way - for example, if the tray drive or the entire CD-ROM fails, if there is a power failure, etc. You usually need to insert a pin or a straightened paper clip into the hole and gently press - this unlocks the tray or disk case, and it can be pulled out manually (although there are drives, for example Hitachi, in which you need to insert a small screwdriver into such a hole and rotate it located behind the front drive panel axle with slot).

Principle of operation DVD drive

What does it consist of?

1. All you can see without opening its case is the tray, which plays the role of a sliding tray where you insert the disk so that the drive can begin working with it later.

2. Hidden in its vast part is a motor that forces the tray to move out of its garage (body) and then return to its original place, regardless of whether it is empty or with contents - a disk.

3. A motor, thanks to which the disk rotates around its axis to the speed declared by the manufacturer. For example, if it is a regular disk type - CD, the reading speed can reach 52X and higher.

4. A motor that allows the structure on which the drive laser is located to move.

5. Board - playing a major role in operation. A kind of computer that receives the master’s commands and forces them to be carried out by the other components listed above, in order to then turn to the master again and send him the result of their actions.

How does it work?

1. The very first thing the drive does after a disk has been placed in it is trying to read data from it. To do this, he uses all of the above components, but the first of them is the tray and its components.

2. Then the design comes into play, which is driven by the motor from point 4, where we describe what the drive consists of. It contains a laser that emits a “beam of light.”

3. The light beam, thanks to a special “guide prism” and its other components, penetrates the surface of the “reflecting mirror”, which, due to the subsequent movement of the structure with the laser, reflects it onto the surface of the inserted disk.

4. When the beam reaches the target, it is reflected again, but from the very surface of the disk. The beam reflected from the disk again appears at the “reflecting mirror”. And here the guiding prism comes into play again, with the help of which the resulting beam penetrates the “photosensitive device” that generates electrical impulses.

5. The final stage can be considered “chewing” the received information by using microcircuits, which in turn send the received data to the computer, or receive it, and, depending on the type of command, get to work.

DVD capacity (layers and sides)

There are currently four main types of DVD discs, classified by the number of sides (single- or double-sided) and layers (single- and double-layer).

· DVD-5 - single-sided single-layer disk with a capacity of 4.7 GB. Consists of two substrates connected to each other. One of them contains a recorded layer, which is called the zero layer, the second is completely empty. Single-layer discs typically use an aluminum coating.

· DVD-9 - single-sided double-layer disk with a capacity of 8.5 GB. Consists of two stamped substrates connected in such a way that both recorded layers are on the same side of the disc; on the other side there is an empty substrate. The outer (zero) stamped layer is covered with a translucent gold film that reflects laser ray, focused on this layer, and transmits the beam, which is focused on the lower layer. A single variable-focus laser is used to read both layers.

· DVD-10 - double-sided single-layer disk with a capacity of 9.4 GB. Consists of two stamped substrates connected to each other by their back sides. The recorded layer (zero layer on each side) is usually coated with aluminum. Please note that this type of disc is double-sided; The reading laser is located at the bottom of the drive, so to read the second side the disc must be removed and flipped over.

· DVD-18 - double-sided double-layer disk with a capacity of 17.1 GB. Combines two recording layers on each side. The sides of the disc, each formed by two stamped layers, are joined together with their backs facing each other. The outer layers (layer 0 on each side of the disc) are coated with a translucent gold film, the inner layers (layer 1 on each side) are coated with aluminum. The reflectivity of a single-layer disk is 45–85%, and that of a two-layer disk is 18–30%. Various reflective properties are compensated for by an automatic gain control (AGC) circuit.

Control questions:

1. What is a disk drive for?

2. What does a disk drive consist of?

3. How the drive works

4. What drive companies do you know?

5. DVD capacity

Related information.

DVD player disk drive

Laser disk drives have become widespread in electronics. Any DVD player, CD/MP3 radio, or stereo system includes a laser drive.

In most cases, such devices need to be repaired precisely because the laser drives break down.

The malfunctions caused by a breakdown of the laser drive are quite similar and boil down to one thing - the laser disc is either unreadable, or music (CD/MP3) or video (DVD) playback fails.

It should be noted that the service life of the laser diode, which is included in any disk device, is on average 3-5 years. It would be naive to think that a DVD player will last 10 years or more! Check your DVD player's manual...

In general, the first thing you need to ask when they bring any disk drive to you for repair is how old the device is and how intensively it was used. If the answer is 3 or more years, then the likelihood that the optical unit is faulty increases sharply. How often the device was used is also important, because a laser drive is an electronic-mechanical device. The number of miniature motors in one laser drive is unlikely to be less than 2-3.

First of three– spindle drive. He is responsible for promoting the laser disc. A very large number of malfunctions are associated with it. Here's an example.

Second– drive of the optical unit. This drive is responsible for positioning the laser head along the disk. Quite rarely it fails.

Third– loading/unloading drive ( LOAD ). Unloading and loading a disc into the drive. Malfunctions of this engine are quite rare, and are usually easy to repair.

In practice, such a malfunction occurs. Mostly CD/MP3 car radio .

The sound often disappears during playback. It suddenly appears and also disappears. There is “stuttering”.

U DVD players The malfunction manifests itself as follows.

It takes a very long time to read the disc, after which the message ( ERROR or NO DISK ). It is possible that the disk may randomly freeze. Reinstalling the disc solves the problem and the recorded disc plays normally.

The reason for this “incomprehensible” behavior is not due to a malfunction of the optical laser unit, but to a malfunction of the spindle drive.

The fact is that the spindle motor must spin up at a certain speed. The speed is adjusted by the feedback system. So you don’t have to think that the disk is spinning on its own. I applied 3 volts to the engine and that’s it! No! The disc rotation speed is regulated by a complex adjustment system. If the spindle motor is faulty, then even the correction system does not cope well and failures occur. The engine does not produce the required speed, “fails”.

Therefore, if the malfunction described below occurs, do not rush to replace the optical laser unit!

Replacing the spindle drive is cheaper than buying an optical laser unit. You can temporarily replace the drive with a motor from another device or find a suitable one in the storage room.

A very common problem is with CD/MP3 radios with vertical disc installation.

The disk spins up, but the disk does not boot. Writes ERROR or NO DISK .

The optical laser unit is protected from dust and dirt. A thin, fine dust deposit on the top lens is enough to make the disc unreadable. Radios with vertical disk installation are more vulnerable to dust; the disk is loaded from above and the amount of dust entering increases.

In this case, disc car radios are more protected; they have slot loading of the disc.

Fine dust deposits can be removed from the surface of the laser unit lens with a regular cotton swab or just a piece of cotton wool. Wet cotton wool with cleaning agents No need, you can ruin the lens! We rub a cotton swab over the surface of the lens in a circular motion 3-4 times. We make sure that there are no large dust residues on the lens and that’s it!

You should not press on the lens; it is attached to spring wires! They supply power to the focusing electromagnet. They are quite strong, but with excessive force they can be damaged.

It is not uncommon that after such simple cleaning, the operation of the device is completely restored.

The main difficulty in this operation is to properly disassemble the device and get to the laser head. This is most difficult to do on music centers with a 3-disc loading unit or changer (when the discs are placed in a box - like plates in a dryer), as well as on car CD/MP3 players and DVD players with slot-loading discs.

Therefore, on the pages of the site I also posted information on disassembling various CD drives.