DIY music center cd drive repair

Disk drive repair. Prevention and Treatment.

Mechanical failures are the main causes of drive failures. They make up about 75-80% of the total number of malfunctions and repairs associated with it. Moreover, most often the reasons for the failure of DVD drives (any, not only computer ones) are contamination of the moving parts of the disc transport mechanism and dust accumulated on the optics. Repairing a drive will almost guarantee it will be adequate to the cost of a new one, so we carefully read and weigh whether the skin is worth the candle.

Repairing a drive is not a trivial task.

The presence of dust and dirt on the moving parts of the mechanism, especially on the edges of the movable carriage sled, makes it impossible to lock the drive mechanism holding the disc, as a result of which the device does not fix the disc and constantly throws it out. If, on the contrary, the drive ejects the tray and immediately picks it up, then, most likely, the cause of the defect is the failure of the tray position sensor. The fact that the tray is thrown out is determined by the drive with the help of a contact sensor, which should be found, try to correct its position, repair or replace. Repairing the drive itself is not necessary here; from time to time, just make sure that dirt does not accumulate in the places where the slide moves.

In order to clean the dust from the drive of the drive, you can first confine yourself to partial disassembly (pull out the tray and remove the front panel), and then blow the interior of the drive with a vacuum cleaner configured to blow out the air flow. It's not about repairing the drive yet.

The optical drive system often fails due to dust accumulated on the focal lens or prism. If blowing out the device does not help, you can try dusting the lens with a soft flannel or a brush, as shown.

Remember that under no circumstances should you use alcohol or solvents for cleaning!

The focus lenses of most modern optical drives are made of organic plastic, and the solvent will irreversibly damage their surfaces. It is best to wipe a heavily soiled lens with a piece of hard paper (at worst with a cotton swab, being careful not to leave any lint). This operation is carried out with extreme caution, as the suspension of the laser itself can be damaged. In this case, repairing a drive will be expensive, almost equal to the cost of the drive itself.

The situation is more complicated with the prism that stands behind the lens - it is extremely difficult to get to it. Moreover, the head, as a rule, is not collapsible, but even if it is disassembled, then you can knock down its settings. Therefore, for most drives, a dirty lens means it is completely unusable. Sometimes the optical system fails even due to an ordinary hair caught on the prism - in this case, again, you can try to blow through the system with a powerful stream of air. Otherwise, the repair of the drive (its cost) will be unreasonably high.

By the way, it is not recommended to use special discs for cleaning optics, supposedly specially designed for this. Most of them will not only fail to clean your drive, but they can even seriously damage it. After all, modern optical drives spin the disc to a very high speed and at the same time have a very delicate reading head, so if your device is dear to you, then do not clean it with the help of such devices. This will no longer be a repair of the drive, but an almost deliberate destruction of the drive.

However, most drives operating under normal conditions do not survive to the stage where dust can cause failures. Most often, the plastic of the lens simply becomes cloudy from time to time and / or from overheating of the drive in the system unit. Disk drive repair consists of an expensive replacement of the laser read head. However, such a malfunction accounts for no more than 10% of cases. Here you can, of course, advise to increase the intensity of the laser glow. For this, the variable resistor installed on the carriage with the laser is regulated. Turn the slider of this variable resistor clockwise by 20-30 °, after which the fact of rotation of the drive motor is checked when the disk is installed. If the disk does not begin to rotate, then turn the variable resistor slider another 20-30 °, and continue this way until the motor starts (it should start and for some time - about 10-20 seconds - rotate at a constant speed) ...

The need to rotate a variable resistor that regulates the intensity of the laser light is due to the fact that over time the power of the laser light flux decreases (aging of the elements, clouding of the lens, etc.), however, after such an adjustment, the optical system usually does not last long anyway. Such allegedly repairing a drive is no longer practiced.

You will hardly be able to eliminate other malfunctions of the optoelectronic information reading system on your own. Despite its small size, the optical system of the DVD drive is a very sophisticated and precise optical device, including servo control systems for the rotation of the disc, positioning of the laser reader, autofocus, radial tracking, and a readout and laser diode control system. Repairing the drive is not worth it in this case.

Typical signs of a malfunction are either the lack of rotation of the disk, or, conversely, its constant acceleration to the maximum rotation speed. When you try to remove a disc from a faulty drive using the controls, the carriage opens with the disc rotating on it.

In the operation of a working system, the following phases should be clearly traced:

• start and smooth acceleration of the disk;

• steady state of rotation;

• interval of braking to a complete stop;

• removal of the disk by the carriage tray from the engine spindle and its removal out of the drive.

You can check that the optical system of the drive is working properly by opening the case of the device and observing its operation. You can verify whether the disc spins up after installation by connecting only the power cord to the drive (the data cable is not connected in this case). If the disk does not rotate after installation, then check whether the laser is shining when the carriage is installed in the working position, but without the disk. Sometimes the glow of the laser is not visible in daylight, so the room needs to be darkened. Observation of the laser lens should be carried out from different angles.

In modern optical devices, the presence of a disc is controlled by the laser itself. If the photosensor installed in the laser carriage receives a reflected signal from the disk, then the electronic circuit perceives this signal as “presence of the disk” and only after that generates a command to turn on the main engine of rotation. Therefore, if the intensity of the laser light is insufficient, then the disk will not spin up and the repair of the disk drive will become inevitable.

The servo system for positioning the information readout head provides a smooth approach of the head to the specified recording track with an error not exceeding half the track width in the modes of searching for the required piece of information and normal playback. The movement of the read head, and with it the laser beam along the disk field, is carried out by the head motor.Engine operation is controlled by forward and reverse motion signals from the control processor, as well as signals from the radial error processor. Typical signs of a malfunction are both the erratic movement of the head along the guides and its immobility.

You can visually check the correctness of the focusing system. At the start of the disc, the control processor generates correction signals that provide multiple (two to three attempts) vertical movement of the focus lens, which is necessary for precise focusing of the beam onto the disc track. When focus is detected, a signal is generated to enable reading of information. If after two or three attempts this signal does not appear, then the control processor shuts down all systems and the disk stops. Thus, the operability of the focusing system can be judged both by the characteristic movements of the focal lens at the moment of starting the disk, and by the signal to start the disk acceleration mode upon successful focusing of the laser beam. Other parameters of the correct operation of the optical system are not visually determined.

Optical drives also have many mechanical components that require lubrication of the rubbing parts. The lack of lubrication leads to the fact that the drive hardly pushes the carriage with the disk, and the carriage lock can generally jam, and then the use of the drive will become completely impossible. The lubricant must be applied carefully, after having completely disassembled the device (the places where it is required are usually clearly visible). Before lubrication, it will be useful to clean the lubrication points of dust and dirt. The fact is that if you miss the moment when it is required to apply lubricant, then the difficulty in sliding will lead to mechanical damage to the parts of the transport mechanism or to a violation of its adjustments, which, in turn, will entail either the stop of the carriage mechanism in an intermediate position, or slipping of the disc during rotation time.

A similar situation can arise due to grease on the friction surfaces of the disc holder due to the frequent use of dirty DVD discs, which ultimately leads to unreliable operation of the drive, even to a complete stop.

Contamination of the disc drive seat and poor clamping of the disc to the seat can be eliminated by cleaning the disc seat with any cloth moistened with alcohol.

You can check if there is enough force to hold the disc against the seat when trying to play a regular disc. If there are no errors or failures during disc playback, and the disc with computer data is still unstable to read, you can take additional measures - bend the springs or increase the weight to increase the pressure on the disc from above.

Other mechanical failures include jamming of the disc on the transport carriage (in this case, the disc does not spin at all). Sometimes this happens because the disc seat spontaneously descends along the motor shaft and the disc touches the elements of the transport carriage. To eliminate this defect, the seat is moved upward along the shaft and its height is selected "by poking" so that the disc rotates without touching the structural elements, and also so that the drive ensures stable reading of all discs. After that, the position of the disc seat is carefully fixed on the shaft.

However, the listed mechanical faults relate mainly to simple mechanisms of relatively cheap drives. Expensive models, as a rule, have complex mechanisms, for which the main type of mechanical failure is fatal breakdown of the mechanism parts. This is most often due to the fact that the user, instead of using the control buttons, pushes the carriage with the disk inside the drive by hand. The consequences of such actions can be the most unpleasant.If a dirty and running mechanism is enough to clean, wipe, and lubricate it to perform its functions properly again, rushing and applying excessive force to the disc tray can cause breakdowns that will cause expensive and time-consuming drive repairs.

Finally, electronic component malfunctions are possible. However, their share is unlikely to exceed even a small fraction of all breakdowns. Unfortunately, modern optical drives are very complex electronic systems, and a faulty microcircuit does not differ in appearance from a working one. Accordingly, repairing a drive at home without preparation is impossible.

Now drives may cost less than a network card or video card, but this does not mean that they are just as simple. The optical drive has a rather complex design and, in addition to the mechanical part, contains at least two microcontrollers, a signal processor (DSP), a secondary voltage source, circuits for controlling mechanics, etc. Moreover, most of the microcircuits used in modern drives are specialized, and therefore, repairing a drive in its electronic part is hardly advisable.

Note that in an optical drive it is quite difficult to diagnose an electronics failure even with a sufficient degree of reliability. Indeed, depending on the error correction strategy chosen by the manufacturer for a particular model and, accordingly, on the complexity of the processor and the device as a whole, in practice this or that drive can work with different disks in different ways. This, by the way, explains a common situation when your disk is easily read on a colleague's machine, but your own PC does not even see it. In cheap models, the correction system can correct only one or two minor errors in a frame of information, and a complex expensive system can restore even serious and extended destruction of information, and it does this in several stages according to a complex algorithm. So the repair of the drive in this case will not work due to the absence of a malfunction as such.

Each manufacturer uses its own chipset or completes it with products from different manufacturers, and, of course, does not attach a description. Due to the fact that for each specific device it is necessary to search for specifications for almost every microcircuit separately, often even the specialists of service centers cannot always restore the operability of your device. If only because the repair of the drive will not be economically justified.

In short, if, after cleaning, checking all the wires and connections, as well as system settings, your DVD drive does not work, and the warranty for it has already expired, you may end up with a situation where you just have to throw out the old one and buy a new one.

Laser drives are widely used in electronics. Any DVD-player, CD / MP3-tape recorder, music center are equipped with a laser drive.

In most cases, such devices are repaired precisely because of the breakdown of laser drives.

Malfunctions caused by a breakdown of a laser drive are quite similar, and boil down to one thing - either the laser disc cannot be read, or the playback of music (CD / MP3) or video (DVD) fails.

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

In general, the first thing to ask when a disk apparatus is brought to you for repair is how old the apparatus has been and how intensively it has been used. If the answer is 3 or more years, then the probability that the optical unit is faulty increases dramatically. 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.

The first of the three - spindle drive. He is responsible for spinning up the laser disc. A very large number of malfunctions are associated with it. Here's an example.

Second - optical block drive. This drive is responsible for positioning the laser head along the disc. It rarely fails.

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

In practice, such a malfunction is common. Mostly in CD / MP3 car radios.

The sound often disappears during playback. It appears abruptly and also disappears. Stuttering is present.

Have DVD players the malfunction manifests itself as follows.

The disc is read for a very long time, after which the display shows (ERROR or NO DISK). The disk may freeze up accidentally. Reinserting the disc solves the problem and the recorded disc plays back normally.

The reason for this "incomprehensible" behavior is not associated with a malfunction of the optical laser unit, but with 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 a feedback system. So don't think that the disc is spinning by itself. Applied 3 volts to the engine and that's it! Not! The rotational speed of the disk is regulated by a complex adjustment system. If the spindle motor is defective, then even the correction system does not handle well and malfunctions occur. The engine does not give out the required rpm, it “fails”.

Therefore, if the malfunction described below appears, 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 store.

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

The disc spins up, but the disc does not load. Writes ERROR or NO DISK.

The optical laser unit is afraid of dust and dirt... A thin finely dispersed dust deposit on the upper lens is enough for the disc to stop being read. Vertical disc recorders are more vulnerable to dust, the disc is loaded from above and the amount of dust that gets in increases.

Disc car radios in this case are more protected, they have a slot loading disc.

Fine dust deposits can be removed from the surface of the lens of the laser unit with an ordinary cotton swab or just a piece of cotton wool. Moisten cotton wool with cleaning agents no need, you can ruin the lens! Using a cotton swab 3-4 times on the surface of the lens in a circular motion. Making sure that there are no residues of coarse dust on the lens and that's it!

Do not press on the lens, it is attached to spring cables! They supply power to the focusing electromagnet. They are quite sturdy, but with excessive force they can be damaged.

It is not uncommon that after such a 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 for music centers with a 3-disc loading unit or a changer (when the discs are placed in a box - like plates in a dryer), as well as for car CD / MP3 players and DVD players with a slot loading disc.

Therefore, on the pages of the site, I posted information on disassembling all kinds of CD drives:

These techniques will help if you need to disassemble a CD drive, but there is no experience in this matter.

Sometimes cleaning the lens does not help. The reason is that there is a prism inside the optical unit, dust will settle on it over time. It makes no sense to disassemble the optical unit. Better to replace the entire block.

When repairing electronics with faults that clearly indicate a defect in the laser drive, you can use the following techniques:

Check the mechanical part of the laser drive for jamming of gears, carriages, serviceability of flexible connecting cables. It is better to “ring” flexible cables with a multimeter, and it is better to check with a replacement. Very often the loop “rings” by the multimeter as if it is working, but since it bends during operation, the bad contact again makes itself felt.

In DVD players, the “weakest” ribbon is the one that connects the laser head to the main board. Replacing it often fixes a problem with a “freeze” disk, bad or long loading of the disk, and playback failures.

Check if there is a laser light. After inserting the disc, the red laser turns on (only for DVD) for a few seconds. At this moment, it is necessary to check the presence of a glow while looking from the side. Remember! Laser is harmful for health! Direct eye contact with the laser beam can result in loss of vision. Be careful!

Clean the lens of the optical unit. How to do this has already been described.

Visually trace the loading of the disc, its spinning. Replace the spindle drive using the substitution method.

If possible, replace, at least temporarily, for inspection, the laser optical unit. Here's how to quickly replace laser in DVD.

In addition to the laser, there may be other causes of the malfunction. I have already talked about the main malfunctions of DVD-players.

The topic of repairing disk devices is quite extensive, here are just a few recommendations and tips. For a deeper understanding of the operation of laser disc players, it will not be superfluous to familiarize yourself with the general principles of operation of such devices. I think the book “CD-players. Circuitry "Avramenko YF, will be very useful for understanding the operation of disk devices.

Troubleshooting Music Centers

The article describes how to eliminate the most likely malfunctions that occur in music centers and other similar household audio equipment: failures or malfunctions in reading CDs of the player, malfunctions of the volume control or LPM tape recorders with a reverse, malfunctioning power amplifiers and a power supply unit.

Being engaged in the repair of music centers of various companies (AIWA, JVC, LG, etc.), one has to deal with a number of the most frequent malfunctions, and regardless of the manufacturer. Although from experience we can say that the devices of more serious companies, such as MATSUSHITA, SONY, etc., are very reliable and fail much less often. Of course, many malfunctions arise through the fault of the user, due to careless handling of the device, however, there are a number of such faults, the reasons for which are related to the aging of parts and assemblies of the device itself, wear of rubber, oxidation of contacts, the presence of a layer of dust, etc.

The most common malfunction in most music centers is poor readability or complete read failure in an audio CD player (CD-DA). This is mainly due to contamination of the laser head, aging and, accordingly, deterioration of the transparency of the plastic lens. Malfunctions are expressed in the fact that the player tries to read the initial tracks of the CD for a long time and, finally, stops. Sometimes it is able to identify the disc and start playing, but it may often fail when playing music.

In case of such failures, first of all, it is necessary to check the operability of the laser itself and the transparency of the lens 3 (Fig. 1 shows a simplified drawing of the laser head), as well as the error correction device on the electromagnet 4. For this, it is enough to open and close the carriage without inserting a CD. music center player. The cover of the device itself, of course, must first be removed so that the laser head is visible.As soon as the carriage moves into place and the rotor of the disk drive motor starts rotating, the lens on the laser head should move up and down using an electromagnet. Moreover, if you look at the lens from a certain angle, you can see a thin red laser beam. If all of the above processes are completed, the laser head is in good working order. Sometimes it is enough to wipe the lens surface with a soft cloth to fix the malfunctioning of reading CDs. This should be done very carefully so as not to damage the lens or rip it off the mount on the electromagnet. If there is no improvement or it is insignificant, it is most likely that not only the lens is contaminated, but also the prism 2 under the lens (see Fig. 1). To clean the surface of the prism, remove the laser head from the device.

The lens and electromagnet are fixed on a metal plate 1. They can be covered with a small plastic snap-on cap. This cap must be removed, then unscrew the fastening screws 6, which press the metal plate to the base 5. Carefully lifting the plate, you can see a small hole under the lens. After winding a small piece of cotton wool on a match and dipping it in alcohol, wipe the surface of the prism. Then very carefully put in place the metal plate with the lens and screw it with screws 6. After that, close the electromagnet of the head with a protective plastic cap and set the head in place. A laser head cleaned in this way in most cases begins to read information normally from a rotating CD. If this does not help, then, most likely, the transparency of the lens has deteriorated or the laser diode is faulty and the laser head needs to be replaced with a new one.

In music centers with a tape recorder, in which there is an autoreverse of the tape movement, some specific disturbances in the operation of the LPM of the tape recorder may occur. When you press the play button, the motor shaft starts to rotate, but after a few seconds it stops. In such cases, rewinding may work.

This malfunction occurs mainly due to the weakening of the belt tension between the engine pulleys and the drive shaft of the tape recorder. In most CVLs with autoreverse used in music centers, instead of a four-track head, a two-track head with a turning mechanism is installed. Rotating the head when reversing the direction of movement of the tape in the tape recorder requires a certain effort at the moment of switching. When the belt tension is weakened (due to rubber aging), the head rotation mechanism is jammed in any position and the CVL stops working. Such a malfunction can be easily eliminated by replacing the old belt with a new one.

Another malfunction that sometimes arises in digitally controlled devices that have worked for several years, manifests itself in the termination of volume control by a regulator located on the device itself; the volume control from the remote control is effective. Such failures occur because in such music centers, instead of ordinary variable resistors - volume controls, special sensors - knobs are installed, when rotating, the corresponding contacts close, and the processor, depending on the direction of rotation of the shaft, changes the gain in the path. If these contacts become dirty or oxidized, they will malfunction and disrupt the normal volume control.

Elimination of the malfunction consists in cleaning the knob contacts. Since it is located on the front panel of the device, disassemble the device. On the front panel of most music centers, there is a large printed circuit board, into which the volume encoder is soldered.After dismantling, it is disassembled by unbending the metal frame-mount, then the internal contact tracks are washed with alcohol, cleaned from the oxide with an eraser (eraser) and washed again with alcohol. Before assembly, the contact tracks are lubricated with a small amount of grease. A repaired rotary encoder will usually work normally for several more years.

Failure of a power amplifier in a music center often occurs due to careless handling - a short circuit of the amplifier output to a common wire or case. Since in most music centers power amplifiers are made on integrated microcircuits, the repair may consist in a banal replacement of the microcircuit with a serviceable one. However, there may be cases when it is difficult to find a similar microcircuit, especially where there are no stores selling imported radio components, and there is no way to stock up on a wide range of elements in advance. There are also cases when, as a result of the combustion of a microcircuit, the inscription on it has disappeared and it is not possible to determine the type of microcircuit. If the circuit of the device could not be found, the device can be repaired by using TDA1557 or TDA1552 instead of the burnt out microcircuit. These microcircuits differ in that they do not require any external elements for operation, and therefore replacing any integrated power amplifier with one of these microcircuits will require a minimum of work. The output power of these microcircuits - 2 × 22 W - corresponds to the majority of mid-value music centers.

At the input 11 of the microcircuit (see Fig. 2), you need to send the Stand-By signal, which controlled the operation of the old microcircuit. It can be found as follows. Connecting in turn to the contact pads at the location of the old microcircuit, a voltmeter or an oscilloscope, turn on and off the music center with a button on the front panel and find a place where, when the center is off, the voltage is close to zero, and when it is on, to the supply voltage. If this signal cannot be found, then in extreme cases pin 11 (Fig. 2) can simply be connected to the positive power bus of the microcircuit.

I have changed the output amplifiers in JVC and Panasonic music centers (one of the MATSUSHITA brands). The results of this replacement of the output microcircuit turned out to be good. If the output power turns out to be slightly overestimated, then it can be reduced to the required level by cutting the tracks on the music center board in the input signal circuit in front of the coupling capacitors and soldering the resistive dividers shown in Fig. 3. By selecting resistors R1 and R3, they achieve the output power reproduced by the loudspeakers of the music center without distortion. It is unacceptable to exceed the output power more than the previous one, as this can lead to failure of the dynamic heads or the power supply of the music center. If you use surface mount resistors for R1 — R4, this modification can be done very carefully without spoiling the appearance of the board.

The described replacement of the power amplifier is also suitable for repairing UMZCH car radio tape recorders; it allows you to significantly increase the quality indicators and output power of an average quality car radio.

And finally, another malfunction, which is also common, is a defect in the mains transformer. In the presence of a circuit and known voltage values ​​on the secondary windings of the transformer, this repair is not particularly difficult, but if this information is not available, problems may arise with replacing the transformer or rewinding it, especially if there are several secondary windings.

It is necessary to eliminate this malfunction, starting with checking the health of the power cord and fuses. If the fuses are turned on in the secondary circuits and the mains voltage comes directly to the primary winding of the transformer, and there is no voltage at its output, most likely the fuse is built into the transformer.This fuse is present in most transformers and is mounted over the primary winding, but other arrangements are possible. If this fuse is not present or it turns out to be intact, and there is an open in the primary winding, then the transformer will have to be changed or rewound accordingly. Rewinding the primary winding in the transformer from the music center is sometimes not easy. Firstly, the winding is filled with varnish, and the wire is thin and it turns out to be impossible to count the turns, gradually winding it up (the wire often breaks). Secondly, even knowing the number of turns, it is often not possible to lay them so tightly during winding as it was done at the factory, and as a result, the wound winding does not fit in the transformer frame or in the magnetic circuit window. Therefore, it is easier to find out what the secondary voltages should be, and wind up another transformer or pick up a ready-made one - since there is usually enough space inside the music center.

It is best to start clarifying the voltage values ​​in the secondary winding circuits by looking for the circuit or any inscriptions about the voltages on the printed circuit board. If this is not the case, then you can try to determine the voltage using one of the microcircuits. Best of all - on the power amplifier microcircuit (having found out the nominal voltage of its supply from the reference book). As noted above, in most cases this voltage turns out to be in the range of 14. 17 V. Knowing it, one can accordingly assume what the voltage should be on the transformer winding. If, for example, the rated supply voltage of the microcircuit is 15 V, then due to the fact that after the diode bridge and filter capacitors the voltage increases by about 1.4 times (at low load), the transformer winding should be respectively 12-13 V. Then you can wind up all the secondary windings of the transformer and count their turns. Since the wire of the secondary windings is quite thick, it is not difficult to do this even with the windings filled with varnish. Knowing the number of turns of the windings and the voltage on one of them, it is no longer difficult to calculate the remaining voltages using the well-known formula

where U_N and U₂ - voltage, respectively, of unknown and known windings; w_N and w₂ - the number of turns of the corresponding windings.

When winding the windings of a new transformer, the wire diameter should be no less than that with which the windings of the old transformer were wound. Even if the voltage of the windings of the new transformer differs from the required by 1-2 V, this will not have a significant impact on the operation of the music center.

Each of the faults discussed in the article may require an individual approach, and the methods for their elimination may differ from those described by the author, however, I hope that the recommendations outlined here will help masters, especially beginners, when repairing music centers and other household audio equipment.

I. KOROTKOV, Bucha, Kiev region, Ukraine

- Hey, do you know where you can buy a new head for my CD player? He broke down.

I've heard this so many times that I decided to write about lasers, their problems and simple solutions.

I looked inside over 100 players that DIDN'T READ CDs and only one (in decimal and binary it is exactly "1") had a broken head. And this one died because of my stupidity. But that is not the subject of this article.

There are at least twenty reasons why a CD player won't read discs, and stereotyped people call all these problems BROKEN HEAD.

And this is EXTREMELY WRONG, because laser heads are no longer produced, and what is left, these holy reserves, are being brutally snapped up by those who know nothing better than to stupidly buy a new head.

- in accordance with "my great experience" in this matter is:

1. CD inside the player, left over in the tray after being moved. The disc falls into the CD's “guts” and blocks the mechanism. When the owner inserts the second disc inside, the player naturally shows an error.

- Treatment: The first medicine that comes to my mind is to open the disc and remove the stuck CD.

2. The 20-year-old belt that powers the tray starts to slip or breaks. After closing the tray - the disc does not fit correctly on the spindle.

3. CD player in a dusty environment. Dust or cigarette tar has settled on the laser optics. Dust causes dispersion of the beam. The laser loses focus.

- Treatment: open the player and clean the surface of the laser head with an ear stick. First with a wet tip moistened with cleaning liquid, then dry. If this is not enough, clean the laser INSIDE the readhead. But this is for the advanced. Better to give this job to a watchmaker. Below are some photos.

4. The power supply to the laser circuit is faulty: either the voltage is too low, or noisy, or starts to oscillate from poor filtering or regulation. Dry electrolytes may be the cause.

- Treatment: replace all the electrolytes in the digital part of the board, or even better - everything.

5. There is cold soldering in the laser circuit. - Indeed, unsoldered connections can corrode and fail over time. Even the best players of 20 years ago are guilty of this. Hot-soldered connections, such as the leg of the regulator, or the point where the voltage is rectified, or the laser power controller - from the heat they begin to accelerate wear - a mixture of oxidation, flux burnout and tin evaporation.

- Treatment: take a look at all solder joints, especially around the laser power cable connectors, around all controls, around areas that look burnt, brownish or welded - and re-solder those connections with some fresh solder with fresh flux.

6. Moving cables or tapes - break after millions of bends.

- Treatment: Check for continuity in the bends of the belts leading to the laser, tray or drive mechanism.

7. The driving mechanism accumulates dirt, hair and dust on the oily part and the head cannot return to the center, its original position. With each ride, the dirt is repelled and forms a kind of "bumper" that remains on each side of the track.

- Treatment: clean the tracks, axles and rods at their edges.

8. The main motor is not holding the correct speed.
It looks as if the laser cannot read the disc, but the point is the wrong rotation speed. This could be caused by the disc sliding on the spindle, or a defect in the engine, or something blocking the CD, such as rubbing against the surface of the tray with a corresponding sound. For example, a spindle can wear out its lower bearing and the whole mechanism will be lower by one tenth of a millimeter. The laser loses focus and the top clamp will not press well. In any case - the spindle must be returned to these tenths of a millimeter.

- Treatment: if the motor is the simplest Mabuchi for 5 bucks, it is better to replace it. If it is a CDM or KSS magnetic series with brushless motors, then simply adjust the spindle height.

9. Hair or something else is stuck inside the laser focusing mechanism.
The laser cannot move up and down freely. If the CD is highly electrified, it attracts hair, dust and pet hair. During playback, they can be hit by the laser focusing suspension.

- Treatment: remove the obstacle.

10. The CD does not spin. After closing the tray, nothing happens and an error is displayed. This may be the result of the CD not spinning at all. The CD drive should be examined.

Even without specialized equipment, we mortals can diagnose the problem quite well, while saving a ton of money in repairs. Or buying a new head. Or even a new player.

If this story is familiar to you firsthand - the laser is REALLY DEAD. A dying laser with twisted power dies very quickly.

An example of deep cleaning of the Sony KSS151A laser:

The first step is to remove the head cover (for example KSS-151A, similar to other Sony heads).