Drive Mechanisms; Mechanics; Cartridge-Load Mechanism; Capstan/Drive-Motor Assembly - Seagate STT20000A Product Manual

Chapter 7

Drive mechanisms

This section generally describes the hardware design features of the STT20000A. You may want to refer to the block
diagrams referenced previously as you read this information.

Mechanics

Cartridge-load mechanism

Capstan/drive-motor assembly

Chassis

Control circuits

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The mechanical package for the STT20000A was designed to provide you with all
the advantages of easy cartridge loading and unloading while maintaining the
positioning accuracy necessary for high-density data recording. The orientation of
the cartridge is the same as the majority of QIC minicartridge drives in the field.
The cartridge is inserted in the drive by sliding it through the aperture in the bezel
and into a tray mechanism. When fully inserted the back portion of the cartridge
protrudes about 3/4-inch from the aperture. A switch is actuated at this point that
causes a microprocessor to complete the loading operation.
When the tape is in motion, the amber LED on the front panel flashes. The LED is
not lit when the tape is positioned at BOT.
In the STT20000A, the cartridge is driven by the capstan/belt motor assembly,
which is on a linear slide. The cartridge is loaded against the cartridge drive roller
which exerts a net radial dynamic force of 18 to 26 ounces. The motor is a brushless
DC drive motor with integral capstan which is designed to provide maximum
reliability.
The motor operates from the 12V nominal supply and moves the tape at speeds
from 35 to 100 inches per second (IPS).
The drive mechanism is mounted in a molded frame that provides the mounting
holes for the industry standard 3.5-inch by one inch form factor. A 5.25-inch
mounting kit is an available option. The bezel is a simple snap-on design that is
available in several standard and custom colors. The front-panel LED is amber and
indicates tape activity.
The control logic module shown in Figure 7-1 includes a buffer manager to handle
data movement between the controller, the buffer, and the tape formatter. This
module also includes logic to perform ECC and CRC generation and testing,
WRITE/READ data formatting, head stepper control, and drive motor control.
Theory of operations
STT20000A Product Manual