Table Of Contents - Quantum Q250 Technical Reference Manual

TAB L E
o F
CON TEN T S
PREFACE
. . ii
SECTION 1. INTRODUCTION .
. . . 1-1
1.1
1.2
Features . . . . . .
Logic Conventions . .
. . . . . . . . 1-1
. . . . . . . . 1-2
SECTION 2.
PRINCIPLES OF OPERATION . . 2-1
2.1 Head Disk Assembly (HDA) . . . . . . . . . . . . . . . 2-1
2.1.1 Base casting Assembly. . . . . . . . . . . . . 2-1
2.1.2 Disk Stack Assembly. . . . . . . . . . . . 2-2
2.1.3 Rotary positioner Assembly (Actuator) . . . . . . . 2-2
2.1.4 Headstack Assembly. . . . . . . . . . . 2-2
2.1.S Automatic Actuator Lock (AIRLOCK) . . . . . . . . . 2-2
2.1.6 DC Drive Motor. . . . . . . . . . . . . . . 2-2
2.1.7 Air Filtration. . . . . . . . . . . . . . . 2-3
2.2 Drive Electronics. . . . . . . . . . . . . . . . . . . 2-4
2.2. 1 Disk Format . . . . . . . . . . . . . . . . . . 2-4
2.2.2 Simplified Explanation--Block Diagram . . . . . . . 2-4
2.2.3 SCSI Bus Physical Interface. . . . . . . . 2-8
2.2.4 SCSI Bus Signal Descriptions . . . . . . . . . . . . 2-10
2.2.S SCSI Bus Timing. . . . . . . . . . . . 2-11
2.2.6 Power Requirements. . . . . . . . . . . . . 2-14
2.2.7 Shorting Plug Options. . . . . . . . . . . . . 2-16
2.2.8 Flex Circuit . . . . . . . . . . . . . . . . . . . . 2-19
2.3 PCB Functional Elements. . . . . . . . . . . . . . . . 2-19
2.3.1 Power-On-Reset (POR) and Warm Reset . . . . . . . . 2-19
2.3.2 Motor Control Circuit . . . . . . . . . . . . . . . 2-20
2.3.3 Electronic Return Spring. . . . . . . . . . . . 2-21
2.3.4 S080 SCSI Bus Controller. . . . . . . . . . 2-21
2.3.S Servo Control, AMC and Servo AGC. . . . . . . . 2-23
2.3.6 Actuator Positioning circuit. . . . . . . . . . 2-27
2.3.7 Read/Write Circuit. . . . . . . . . . . . . . . 2-27
2.3.8 FYLO Timing Controller IC, and xtal Oscillators . . 2-29
2.3.9 DICEY Data Controller IC. . . . . . . . . . 2-30
2.3.10 Microprocessor and EPROM . . . . . . . . . 2-32
2.4 Power-Up Sequence/Recalibration. . . . . . . . . . . . 2-32
2.S Read Command Sequence. . . . . . . . . . . . . . . 2-33
2.6 write Command Sequence. . . . . . . . . . . . . . . . 2-33
SECTION 3.
ENGINEERING DRAWINGS .
. 3-1
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