DISK PACk
DRIVE FUNCTIONAL DESCRIPTION
The drive contains all the circuit and mechanical devices nec-essary to record data on and recover it from the disk pack (re-fer to figure 1-2). The power required for this is provided by the drives power supply. which receives its input power from the site main power source.
All functions performed by the drive are done under direction of the controller. The controller communicates with the drive via the interface which consists of a number of I/O lines car-rying the necessary signals to and from the drive.
Some interface lines. including those that carry commands to the drive are not enabled unless the drive is selected by the controller. Unit selection allows the controller. which can be connected to more than one drive. to initiate and direct an op-eration on a"specific unit.
All operations performed by the drive are related to data stor-age and recovery (normally referred to as wri ting and read-ing). The actual reading and writing is performed by electro-magnetic devices called heads that are positioned over the re-cording surfaces of the rotating disk pack. There is a sepa-rate head for each surface in the pack and the heads are posi-tioned in such a way that data is written in concentric tracks around the disk surfaces (refer to figure 1-2).
Before any read and wri te operation can be performed the con-troller must instruct the drive to position the heads over the desired track (this function is called seeking) and also to use the head located over the surface where the operation is to be performed (head selection).
After selecting a head and arr1v1ng at the data track. the con-. troller still must locate that portion of the track where the
data is to be written or read. This is called track orienta-tion and is done by using the Index and Sector signals gener-ated by the drive. The Index signal indicates the logical be-ginning of each track and the Sector signals are used by the controller to determine the position of the head on the track with respect to Index.
When the desired location is reached. the controller commands the drive to actually read or wri te the data. During a read operation the drive recovers data from the pack. and transmits it to the controller. During a write operation. the drive re-ceives data from the controller. processes it. and writes it on the disk pack.
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I-'
The drive is also capable of recognizing certain errors that may occur during its operation. When an error is detected. it is indicated either by a signal to the controller or by a main-tenance indicator on the drive itself.
DRIVE PHYSICAL DESCRIPTION GENERAL
The following describes the physical characteristics drive. The discussion is divided into two major areas semblies and (2) logic and circuitry.
of the (1)
as-ASSEMBLIES
The major drive assemblies are shown on figure 1-3 and describ-ed. in table 1-2. A more complete description of the drive as-semblies is found in the Parts Data Section of the maintenance manual.
Actuator
Blower Assembly Deck Cover
Drive Motor Front Door
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TABLE 1-2. DRIVE ASSEMBLIES
Contains voice coil and This assembly positions over the disk pack.
carriage.
the heads Contains a blower motor that
circu-lates cooling air for the drive.
Provides an electrical interference shield for the drive and also reduces noise level output from drive.
Provides rotational motion that turns spindle and disk pack.
Provides access to blower assembly and the lower front part of cabinet.
Table Continued on Next Page
1-9
TABLE 1-2. DRIVE ASSEMBLIES (Contd)
Heads Detect data transi tions that are on the pack if drive is reading. Writes data transi tions on the disk pack if drive is writing.
Logic Chassis Contains logic cards that control op-eration of drive.
Magnet Provides permanent magnetic field
that is used In conjunction with voice coil to move carriage and heads.
Operator.Control Contains switches that allow operator Panel to control and moni tor basic
opera-tion of drive.
Pack Access Cover Provides access to disk pack and pack area.
Pack Access Cover Solenoid (Note 1) Pack Access Cover Switch (Note 1)
Pack On Switch
Parking Brake Power Supply
Read/Write Chassis
Prevents pack access cover from being opened if the pack is spinning.
Interlock that deenergizes drive mo-tor if pack access cover is opened while pack is spinning. It also pre-·
vents motor from starting unless cov-er is closed.
Interlock that prevents from starting when pack stalled.
drive motor is not in-Holds spindle while disk pack is
be-ing installed and removed.
Furnishes all necessary voltages for drive operation.
Contains cards that are essential to drive read/write operations.
Table Continued on Next Page
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TABLE 1-2. DRIVE ASSEMBLIES (Contd)
Rear Door Provides access to power supply, log-ic chassis and lower rear of cabinet.
Shroud and Provides protection and ventilation Shroud Cover for disk pack.
Side Panels
spindle and Lockshaft
Top Cover
Notes:
Provide access to either side of drive.
Provides mounting surface for disk pack. Lockshaft secures disk pack to spindle. Drive motor transmits rota-tional motion to spindle via drive belt thereby causing pack to rotate.
Covers entire top of drive thereby protecting drive assemblies and re-ducing output noise level.
1. The pack access cover interlock swi tch and solenoid are part of the interlock assembly on VDE units.
LOGIC. AND I CIRCUITRY'
The drive contains integrated and discrete component circui ts as well as relays, switches and other electromechanical ele-ments. All of these work together in performing the various drive functions.
Diagrams showing all circuits and interconnecting wiring are contained in the maintenance manual.
EQUIPMENT CONFIGURATION GENERAL
The equipment configuration is identified' by the cabinet iden-tification plate and by the FCO log. It is necessary to iden-tify the equipment configuration to determine if the manua Is being used are applicable to the equipment. The following des-cribes the cabinet identification plate, FCO log and manual to equipment correlation.
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TOP COVER DECK COVER
r r~ I) i IT 0 Q U R SIDE P,ll.NEL
Figure 1-3. Drive Assemblies (Sheet 1)
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SPINDLE
SHROUD
PARKING---~~~~~~~~~~~~
BRAKE
&
PACK ACCESS COVER SOLENOID
PACK ON SWITCH SPEED SENSOR
ACTUATOR
&PART OF INTERLOCK ASSEMBLY ON VDE UNITS.
&INTERLOCK ASSEMBLY ON VDE UNITS
READ /WRITE CHASSIS
&
PACK ACCESS COVER SWITCH
POWER SUPPLY
9E87-2C
Figure 1-3. Drive Assemblies (Sheet 2)
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EQUIPMENT IDENTIFICATION PLATE GENERAL