Repair and maintenance of CD-ROM drives. Scheme, description

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Repair and maintenance of CD-ROM drives. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Computers

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The article discusses the main defects of CD-ROM drives (drives) and ways to eliminate them. The experience of operating personal computers shows that in the general flow of failures these devices occupy fourth place (after monitors, hard drives "and floppy drives). When considering malfunctions, it is assumed that the CD-ROM drive is correctly installed in the computer's operating system and correctly paired with related boards and power supply.The most common malfunctions of CD-ROM drives are the following.

1. The device is not available to the operating system

At the same time, the disk is loaded normally - the transport mechanism is working. First of all, the connection to the CD-ROM drive of external connectors is checked to exclude the influence of bad contacts. Then, if possible, change its connection, i.e. change the port on the motherboard (IDE0 or IDE1). You can also try connecting the device to a special IDE connector on the sound card. Finally, the correct setting of the MASTER-SLAVE switch is checked. If the device has a SCSI interface, you should change its address.

repair and maintenance of CD-ROM drives

If all this does not lead to a positive result, open the device and make sure the solder connections of the information connector, power connector and device activity (address) switch are reliable. Then check whether the drive motor shaft rotates with the disc. If it does not rotate, check the health of the engine. Having disconnected both of its wires from the printed circuit board, a constant voltage of 5 V is applied to them from an external source in accordance with the color of the wires ("+" - red, - "black). The rotation of the motor shaft indicates that the fault should be sought in the control circuits them Which of the microcircuits (there are only two or three of them on the printed circuit board) controls the electric motor is determined by the printed conductors going to it, to which the wires from the engine are soldered. common wire bus (photo 1).

Next, measure the voltage at the power supply terminals of the control microcircuit, as well as the temperature of its case (it should not be higher than 35 ... 40 ° C). The darkening of the printed circuit board under the microcircuit and the elements located next to it indicates a high operating temperature of these parts, which requires their verification. If it was not possible to identify the faulty element, the microcircuit should be replaced first. A speed stabilizer can be placed in the drive motor housing (four or more wires are connected to the motor). In this case, first of all, the stabilizer chip is replaced. If this is not possible (no access, filled with compound), the entire engine assembly should be replaced.

2. When pressing the eject button, the transport mechanism does not work

With such a malfunction, you need to make sure that voltage is supplied from the input connector of the CD-ROM drive to its electronic components. Then, in accordance with the above algorithm, the serviceability of the button, the electric motor of the transport mechanism and its control microcircuit are checked. In some devices, you also need to make sure that the rubber belt is intact, which transmits rotation from the electric motor to the working gear wheel of the transport mechanism (pictured 2).

3. The CD-ROM drive is unstable, and the information is read with a large number of errors

In such a case, on the opened device, it is first checked whether the laser glow (red) appears for 2 ... 10 s when the transport mechanism is set to the working position. The glow can be seen only at a certain angle of view in a darkened room (in no case should you look into its lens - it is dangerous for the eyes!). The carriage with the laser at this moment should move back and forth, and the drive motor should turn on for a short time. After making sure that everything is working properly, lift the upper disc lock and manually move the transport mechanism to the CD-ROM installation position, thereby opening access to the laser lens (photo 3). With a soft brush, carefully clean the lens of dust. This must be done with great care so as not to damage the laser suspension.

Further, by moving the transport mechanism or disassembling it, the seat of the laser disk on the drive motor (drive gear) is released. After that, the landing disk is first cleaned of dust with alcohol (rubber ring - photo 2), and then the upper clamping ring (if, of course, there is one). Finally, the rest of the mechanical part of the device is cleaned of dust, the movement of the laser carriage is checked and, if necessary, its guide is lubricated with technical vaseline.

4. When rotating, the CD-ROM touches the elements of the drive

Check the fastening of the drive motor or landing disc. If it is weakened or has a large backlash (roll), the defect should be eliminated.

That, perhaps, is all that a specialist with average training can do. However, this is not so little. According to statistics, malfunctions of electric motors, their control microcircuits, as well as contamination of the disk drive and laser lens, account for more than 50% of all failures of CD-ROM devices. Note that the troubleshooting tips in steps 1-3 also apply to CD-ROM burners. Troubleshooting algorithms for the laser, the drive mechanism of its carriage, the control device and the interface with the external interface are not considered here, since they require special skills in each specific case. Increased noise or hum emitted by the drive when working with individual laser discs (typical for devices with high read speeds) is not a malfunction, for some types of CD-ROM devices this is a normal mode.

Finally, some helpful tips. In order for the CD-ROM drive to serve for a long time and reliably, you must adhere to some rules:

Purchase licensed CD-ROMs whenever possible. If you bought a "pirated" disc, be sure to check it for warping, the absence of notches around the perimeter, etc.;
at least once a year, clean the device from dust, as described above;
prevent dust and contamination of laser discs and, if necessary, clean them with a cambric cloth moistened with alcohol;
do not use so-called cleaning discs for CD-ROM devices.

Author: A. Rodin, Moscow; Publication: cxem.net

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