Seagate ST212 - Page 5

6.1.2 Write Gate 23
6.1.3 Write DataProcessing 23
6.1.4 Precompensation 23
6.2 Write Operation: PC Board 20243-XXX 24
6.2.1 Write Gate ' 24
6.2.2 Line Receiver 24
6.3 Formatting 25
6.4 Read Operation: PC Board 20292-XXX 26
6.4.1 MFM Read Data ' 26
6.4.2 Head Select 26
6.4.3 LSI Preamp 26
6.4.4 Low Pass Filter 26
6.4.5 Read Data Conversion 26
6.5 Read Operation: PC Board 20243-XXX 27
6.5.1 Head Select 27
6.5.2 LSI Preamp ~ 27
6.5.3 Low Pass Filter 27
6.5.4 Phase Shifter ;, 27
6.5.5 Zero Cross Detector 27
6.5.6 Time Domain Filter 28
6.5.7 Line Driver 28
7.0 MICROPROCESSOR 29
7.1 MPU: PC Board 20292-XXX ...........................•........ 29
7.2 MPU: PC Board 20243-XXX 30
8.0 MOfOR SPEED CONTROL 31
8.1 Motor Speed Control: PC Board 20292-XXX 31
8.1.1 Hall Effect Transducer 31
8.1.2 Spindle Motor Control LSI 31
8.2 Motor Speed Control PC Board: 20249-XXX 31
8.2.1 Hall Effect Transducer 32
8.2.2 Speed Reference Circuit 32
8.2.3 Pulse Shaper 32
8.2.4 Integrator 32
8.2.5 Current Limit 32
8.2.6 Microprocessor: Motor On 32
8.2.7 Motor Drivers 32
8.2.8 Dynamic Brake 32
9.0 FIELD SERVICE ' 33
9.1 Test Point Data: PC Board 20292-XXX 33
9.1.1 DifferentiaI Read Filter: Test Points 1 and 2 34
9.1.2 Track 0 Sensor: IC 3B, Pin 1 34
9.1.3 Index Sensor: Test Point 9 34
9.2 Test Point Data: PC Board 20243-XXX 35
9.2.1 DifferentiaI Read Filter: Test Points 1 and 2 35
9.2.2 Read Data: Test Points 3 and 4 36
9.2.3 Track 0: Test Point 5.- 36
9.2.4 Index Sensor: Test Point 6 36
9.3 Field Accessible Components 36
9.3.1 Main Control PC Board 37
9.3.2 Motor Control PC Board Removal (MLC-OO only) 37
9.3.3 Index Sensor Removal 38
9.3.4 Installing the Optional Full-height Front Panel 38
9.3.5 Track 0 Sensor Removal 39
Schematics
PCB 20243-XXX .......................•..... ' 41
PCB 20249-XXX 43
PCB 20292-XXX ' .. ' 45
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