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       USING THE HELIOS SECTION OF THE SERVICE MANUAL
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I. The 3 main sections
   a) HELIOS II as a system:  MACRO VIEW
   b) The Persci Drive
   c) Sol SYSTEM III
    
    
   A. Helios System macro
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1-22     1. theory of operation for the lay technician
         2. why the Helios system
           a) disadvantages
              1) Incompatibility with IBM format and more comple
           b) advantages
              1) maximum disk utilized
              2) speed and versatility of the DOS
 23-32  3. DISKT the Disk Test Program
           a) What it does and how
    
    
B. PERSCI DRIVE
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  1-6      1. Mechanical problems and solutions
  6-11     2. Circuitry problems and solutions
  11-38    3. Simu-ciser and alignment proceedure
  40-80    4. Parts lists, Assembly drawings & Schematics
    
    
C.  Sol SYSTEM III           (pages 1-4)
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    1. Analyzing the systems operation
    2. Systemic approach to troubleshooting
    3. DOST- test using the DOS and PTDOS commands (slip sht)
    4. Troubleshooting flowchart for the System III
    
    
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                      DISK DRIVE INTRO
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I. 90% of Helios problems are centered in the drive
   A. Compare to british sports car
      1. precise, fast, and quality
        a. one drawback like the car is must be tuned by someone
           who understands the product
   B. All drives share the common problems but Persci has had
      to sacrafice something for speed as is always the case
    
    
II.  What is required of a Drive  ????
     A. Diskette must spin to retreive and store on media
     B. Must keep track of diskette revolution (INDEX, SECTOR)
     C. Head must be able to move from track to track
     D. Head must then be able to READ / WRITE / ERASE
     E. Must provide seperated clocks and data from the disk
        to the controller board
    
    
III.  The 5 PCBs and their functions
    
     A.  Spindle Servo Control board----> turn diskette
     B.  Positioner Servo Control PCB---> Move head track -track
     C.  Lamp Amp PCB---> Keep track of head movements
     D.  Phase Locked Loop Double F Data Seperator--->clock/data
     E.  Data & Interface PCB -------> many tasks
    
         1. I/O selects, head loads, spindle enable, basically
            handles all I/O between disk and Controller
    
         2. Distributes all the power required by other boards
    
         3. Spindle motor reference oscillator
    
         4. Stepping counters to keep track of stepping process
            a. also restore logic  and direction logic
    
         5. Decode sector and Index
    
         6. Write/Read amplifying / gating and decoding
    
         7. Status reporting back to controller / software
            a. Ready --> Index, select, diskette speed
            b. Seek Complete --> tells controller head is not in
               motion
            c. INDEX pulse for syncing on formatter board
    
    
IV.  SIMU-ciser
   A. What an alignment program must provide
      1. Restore the head to track 0 for intitialization
      2. Seek to any specific track
      3. Seek between any 2 tracks
      4. Step seek between any 2 tracks
      5. Load heads and select units
      6. Read and Write to diskettes
   B. How SIMU handles these and overview
    
    
    
V. ALIGNMENT  ===>> DIAGRAMS
      1. Why --> Dirt, age, wear, motion, circuit problems
      2. When --> routinely>>>>>>> suspect a drive problem
      3. What is required -->> Proceedures
                               Tools and Scope
                               SIMU and alignment diskette
    
      4. How
           a. SKIM alignment proceedures
           b. division of related sections of alignment section
    
    
VI. Summary of problems
     A. Alignment most common
     B. Mechanical failure second most common
     C. Cabinet affecting the alignment and the new designs
     D. Problem sections of the manual
    
    
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              WHAT IS MISSING FROM THIS MANUAL
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 I. PERSCI theory of operation macro view
    
II. Troubleshooting and Diagnostic proceedure
    A. elaboration of the Helios Manual Section with
       waveforms and diagrams
    
III. Chip by chip troubleshooting guide --->> won't be added
    
    
    
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NOTE:  This manual is the result of you and your feedback
       and needs your imput ===>> please help us ...
       Corrections and additions are welcome...
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End  ?