FD-5 MAINTENANCE AND ALIGNMENT INFORMATION
(FOR INFORMATION PURPOSES ONLY)
1 .OUTLINE OF MAINTENANCE
• The following tools are required for maintenance of a Floppy Disk Drive
1.1 Alignment Diskettes
Alignment diskette is used for head actuator alignment and index sensor alignment. Use the JU-01AA - DD and 817-363CE.
1.2 Exerciser
The exerciser enables you to make all adjustments and inspections necessary for an FDD. Its functions include the
following:
(1) Seek increment or alternate tracks
(2) Read (but no data compare)
(3) Write 1 F or 2F (All 0's or 1 's)
(4) Recalibration to track 00The exerciser has switches and indicators to execute a specified function.
2.1 Error Symptom Recognition
Errors that occur because of the wrong operating procedure, wrong programming, or use of a defective diskette, or soft errors due to external causes, such as contaminated air and random electrical noise, are often attributed to a drive failure. Unless a visual inspection of the drive reveals an evident assembly fault or a defect, always confirm errors with another good diskette, and another known good drive.
2.2 Soft Error Detection and Correction
Soft errors are normally caused by the following:
(1 ) Contamination between read/write heads and diskette. This kind of contamination can be easily eliminated by the liner in the diskette. Contaminated heads can be cleaned by a general purpose non-abrasive head cleaning diskette. Please follow the suitable procedure provided with the cleaning diskette.
(2) Random electrical noise, normally a few microseconds or less.
(3) Small defects in written data and/or track not detected during write operation may cause soft errors during read.
(4) Faulty grounding of the drive or host system can also cause a soft error.
(5) Wrong motor speed is another cause of soft errors.
Take the following steps on the controller side to recover from the soft errors mentioned above.
(1) Read the track again ten times or until the data is recovered.
(2) If Step (1) above fails to recover the data, access the adjacent track. Then return the head to the original track.
(3) Repeat Step (1 ).
(4) Any error that cannot be corrected by the above procedure is irrecoverable.
2.3 Write Error
If an error occurs during write operation, it is usually detected during the next revolution by performing a read operation called write check. To correct an error, write again and repeat a write check operation. If the result is unsatisfactory after ten or more write operations, perform a read operation on another track to determine whether it is the diskette or the drive that is wrong. If an error persists, replace the diskette and repeat the above procedure. If the error still persists, consider the drive defective. If the error is corrected, dispose of the diskette as defective.
2.4 Read Error
Most read errors are soft errors. Data can be recovered by following the recovery procedure mentioned in 2.2.
2.5 Seek Error
(1) Stepper motor or stepper motor circuit drive is faulty.
(2) Faulty Carriage
There are two ways of seek error recovery. One is to recalibrate to track 00, and seek back to the original track. The other is to read the ID field, check the track number on which the head is located, and move the head away from it. And read it again.
2.6 Interchangeability Error
Data which is written by one drive may not be read by another. This error is called an Interchangeability error, which can be
caused mostly by the following reason, which should be checked as follows.
(1) Head misalignment: Refer to Adjustments and Confirmation Item 5.5
(2) Head output too low: Refer to Adjustments and Confirmation Item 5.3
(3) Motor speed difference: Refer to Adjustments and Confirmation Item 5.1
(4) Format difference
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