3.1.10 PROBLEMS OF HDD THEREOF THEIR CHARACTER OF MANIFESTATION, TECHNIQUE OF THEIR ELIMINATION

The main internal elements of the drive are the frame, the spindle motor, the head unit with the drive and the electronics board.
HDMD includes:

• GMD,
• disk drive
• disk management controller
• the device positioning GCHZ on the desired track,
• device reading and writing information
• interlocking devices.

Spindle motor is a flat multi-pole motor with a constant rotation speed of 300 rpm. The engine drive unit heads - stepper, with a worm, gear or belt drive. To identify the properties of a floppy disk on the electronics board, near the front end of the drive, three mechanical sensors are installed: two - under the protection holes and the recording density indicator, and the third - to determine the moment when the floppy disk is lowered.

GMI has 4 holes:

1. for the motor axis
2. window for GPZH,
3. to index the sector
4. to protect against recording information.

The diskette inserted into the slot gets inside the diskette frame, where the protective curtain moves from it, and the frame itself is removed from the stopper and goes down, the metal ring of the diskette rests on the shaft of the spindle motor, and the bottom surface of the floppy disk is on the bottom head (side 0 ). At the same time, the upper head is released, which is pressed against the upper side of the diskette under the action of a spring.

On most drives, the speed of lowering the frame is in no way limited, which is why heads make a significant impact on the surfaces of a floppy disk, and this greatly reduces their reliable operation.

In some models of drives (mainly from Theas), a micro-lift retarder is provided for a smooth lowering of the frame. To extend the life of floppy disks and heads in drives without a microlift, it is recommended that when inserting a floppy disk, hold down the disk drive button with your finger, preventing the frame from dropping too quickly.

On the shaft of the spindle motor there is a ring with a magnetic lock, which at the beginning of the motor rotation tightly captures the ring of the floppy disk, at the same time centering it on the shaft. In most models of disk drives, the signal from the diskette lowering sensor causes a short-term start of the engine in order to capture and center it. The drive connects to the controller using a 34-wire cable, in which the even wires are signal and the odd wires are common. The general interface option provides for connecting up to four drives to the controller, an option for the IBM PC - up to two.

In the general case, the drives are connected completely parallel to each other, and the drive number (0 ... 3) is set by jumpers on the electronics board; In the IBM PC version, both drives are number 1, but they are connected using a cable, in which the selection signals (wires 10-16) are turned upside down between the connectors of the two drives.

Sometimes pin 6 is removed from the drive connector, which in this case plays the role of a mechanical key. The drive interface is quite simple and includes device selection signals (four devices in general, two in the IBM PC version), engine start, moving heads one step, recording starts, read / write data, as well as information signals from the drive — the beginning tracks, a sign of installation of heads on a zero (external) track, signals from sensors, etc. All work on coding information, searching for tracks and sectors, synchronization, error correction is performed by the controller.

Table 16. The distribution of signals at the connector (ribbon cable) interface of the floppy disk drive - floppy disk drive

Standard format floppy type HD (High Density - high density)

- 80 tracks on each side, on each track 18 sectors of 512 bytes. Compressed format - 82 or 84 tracks, up to 20 sectors of 512 bytes, or up to 11 sectors of 1024 bytes.

Basic requirements for storage of GMI

1. Store in bags and storage.
2. Do not write on them with a pencil or ballpoint pen.
3. Do not throw, do not "test for a break."
4. Do not store near electromagnetic emitters of power supplies, magnets and heat sources.
5. Destroy damaged GMI.
6. Use quality and brand GMI.
7. Check the virus for viruses regularly.
8. Remember that cheaper GMIs have a thinner magnetic layer that crumbles easily, reducing the GMD's performance.

Prevention of NVD

Prevention can be carried out in accordance with the following recommendations:

• estimate the daily time of the drive with a lit LED;
• vacuum clean every month;
• Some manufacturers of floppy disks recommend monthly demagnetization of the drive heads;
• Every six months, check the speed of the drive, the alignment of the heads (using a special adjustment disk);
• as dirt on the floppy disk heads clean them with non-abrasive, abrasive or “wet” cleaning floppy disks, you can also clean them manually with alcohol. A useful rule is: to clean the reading head (writing) every 40 hours of operation of the HDD;

The control controller GMD is made on one or more LSI. The readout signal from the MSS is fed to the controller in a sequential code,

then in parallel code goes to the microprocessor data bus. The nominal frequency of GDFZ usually varies in the range of 62.5-250 kHz.

The positioning device, depending on the disc standard, provides an accurate selective installation of the MSP block on the track. The read and write device is usually made on rigid logic and provides the matching of the MSP input / output signals with the controller. There are 2 sensors in the NGMD - the sensor of the start marker of the track DMND and the sensor “00” of the track (DND). DMND triggered when the hole in the GMD falls into the opening between the LED and the photo transistor.

In this case, a pulse of a marker of the beginning of a track with a duration of at least 600 ms is formed.

DND is usually performed in two forms: either the last “00” track is fixed with the help of a photodiode and an LED, or with the help of a blocking contact that fixes the extreme position of the code screw of the stepping motor that moves the ESS.

Diagnostics of malfunctions NGMD

It so happens that on a normally working computer, the floppy drive does not read or write well on diskettes. Most often this indicates the poor quality of the floppy disks themselves. However, if other computers read floppy disks normally, then you should conclude that the drive is faulty.

Before diagnosing a faulty HDD, make sure that all express tools available to the user have been tried, namely: check the reliability of the MV cable connection with the HDD, the presence of +5 V and +12 V supply voltages in the HDD.

Sound and visual indication of errors should be used as much as possible. For example, if an error occurs when you start your PC, in the case of a faulty floppy disk drive, one short signal sounds and the system error code lights up on the display:

- 6ХХ code, for example: code 601 - Diskette error or the controller board, cable, disk drive is faulty;

- Code 602 - Diskette Boot Record error;

- Code 606 - a malfunction in the design of the drive or on the motherboard controller;

- code 607 - the disk is write-protected, the disk is inserted incorrectly, the disk write protection switch is bad, the fault is in the analog part of the electronic floppy board;

- Code 608 - HMD is faulty;

- code 611-613 - fault on the drive controller board or in the drive data cable;

- Code 621-626 - a malfunction in the design of the drive.

If the fault cannot be localized, then you should try the drive to another system unit and repeat the download. If it fails again, then the drive unit with its electronic board is faulty.

Most often, the electromechanical part of the drive design is faulty, namely, the drive drive is faulty, the stepping motor for moving out of the vehicle, the index sensor does not function, the emergency warning is down, the adjustment of the driver is outdated, and so on.

By the way, violations of the adjustment of GZhZ meet quite often. The PC user must skillfully use existing software diagnostics drives, which can quickly locate the problem. After localization of the faulty board or node, the user can proceed to repair them.

The main causes of a malfunction of an OVMD may be the following reasons:

• wrong type set in SETUP ("flew off" SETUP) - set correctly;
• broken contact in the connectors - open the case, remove the cable, gently put back;
• drive controller (multicard) controller is faulty - as a rule, the computer itself reports this when it is turned on - replace m / s with MIO;
• drive contamination - use a special cleaning floppy;
• really serious damage that requires replacing the drive.

To facilitate the diagnosis of NVMD, the company Teas (Japan) proposes to conduct 15 general inspections, of which the first four are mechanical and the rest are electronic.

It should be noted that in all diagnostics drives there is a set of test points. For example, there are 8 control points in Teas type FD-55BR / FR / GR drives, namely:

1. TP1 - INDEX - check the index signal,
2. TP2 — Erase gate delay — signal erase delay,
3. TRZ - TRACK OO - signals index zero dorzh-ki,
4. TP4 — Rge-AMR — signals of the 1st-side recording amplifier,
5. TP5 — Rge-AMR — Record Booster, 2nd Side of Floppy Disk, '
6. TP6 — DC O — zero track signals,
7. TP7 — DIF.AMP — signals of the 1st-sided reading amplifier,
8. TP8 - DIF.AMP - signals of the 2nd side readout amplifier.

Sometimes gdmd reads information only from those floppy disks that were previously formatted on it. The reason for this may be the following:

• the adjustment of the magnetic heads block is broken,
• zero track sensor shifted,
• disk drive rotation speed has changed
• faulty quartz master oscillator controller floppy disk drive.

Sometimes there is a situation when a floppy disk drive reads only the first inserted floppy disk, and all subsequent ones do not. The cause of this malfunction is the lack of a signal about a floppy disk change (DC-disk changed), which passes through the extreme 34 interface wire. The floppy disk change sensor is an optoelectronic pair installed in the disk drive. Therefore, more accurate reasons may be:

• contamination or malfunction of the optocoupler;
• contact failure in the connectors to which the interface is connected;
• break of the 34th wire in a loop;
• a controller fault on the board (possibly a broken track).