The Winchester disk drives adopt «Maintenance free» concepts. To ensure high reliability, disk and head are enclosed in an air tight enclosure, which provide protection against dust.
Levelingzone(contact start / stop zone) and automatic carriage lock(park) mechanism provide a guarantee against head or disk damage. Even when it gives problem, there is hardly any scope for troubleshooting.
Fault related to Hard disk assembly(HDA) should not be attempted in field, as it may disturb the units in the sealed enclose. These are serviced only in the special designed dust free clean room with high precision tools.
The problem related to HDD are classified into 3 types:
- Mechanical failures
- Electronic failure
- Data failure
Mechanical failures can occur in following circumstances
- Worn-out ball bearing in the spindle or motor.
- Torn or broken belt connecting the spindle to the motor.
- Winding burned out the motor.
- Head crash due to dust.
Electronic problems: This problems are related to the microprocessor PCB, it has many test points.
- Differential read filters
- Read data
- Track 0 sensor
- Index sensor
- Bad spot on the platter.
- Dust and contamination on the platter surface.
- Dust on the read/write head.