SS to DS Drive

                    |*|  ST DISK DRIVE CONVERSION  |*|
                    |*|   SINGLE TO DOUBLE SIDED   |*|
 The single sided Atari SF354 disk drive can be converted to a double
 sided drive for $94.  It is completely equivalent to the SF314 except
 that it uses far less power.  The SF354 contains an Epson SMD130 drive
 and the SF314 contains an Epson 140 drive.  In addition, both drives
 contain a connector board at the rear of the drive housing which
 interfaces the Atari cables to the headed sockets which plug into the
 Epson drive.
 The boards also have jumper wires which tell the 520ST what type of
 drive is connected.  The cases for both drives are identical (except for
 the SF354/SF314 marking on the outside.) There are eight Epson SMD-100
 series disk drives.  The SMD-130 and SMD-170 are interchangable single
 sided drives.  Similarly, the SMD-140 and SMD-180 are interchangable
 double sided drives.  The difference is that the SMD-130 and SMD-140 are
 intended for AC powered equipment and consume 1.3W on standby and 6.9W
 on read/write.  The SMD-170 and SMD-180 are designed for use with both
 AC and battery powered equipment and use 0.3W on standby and 2.9W on
 A good source for the Epson SMD-180 drive is:
                        Halted Specialties Co. Inc
                           827 E. Evelyn Avenue
                              (408) 732-1573
                           Sunnyvale, CA 94086
 The cost is $89 plus $5 shipping.  They accept phone orders using a
 credit card and ship via UPS.  Since the cost of a SF314 is about $219
 the conversion results in a considerable saving.  The only problem is
 what do you do with the old single sided drive?
 To convert the drive, proceed as follows:
 1.  Remove the four screws around the perimeter of the SF354 disk drive
     and gently lift the rear of the cover while lightly pressing in the
     disk connector sockets at the rear.  The sockets and switch should
     should pop free and then the top can be unhocked from the disk
     active LED and disk eject switch at the front.
 2.  Carefully unplug the two socket connectors between the interface
     board and the rear of the SMD-130.  Use a small, flat bladed
     screwdriver to gently and evenly pry them free.  Looking at the top
     of the board in the lower left-hand corner is a place for a jumper
     wire marked W1 between locations SG and FG.  Connect a piece of wire
     between these point and solder it in place.  Turn the board over and
     rotate 180 degrees.  Find the four parallel jumper wires on the
     right hand side.  Remove the first and third wires, either by
     cutting them away or unsoldering them.  This completes the
     modifications to this board.
                                                      1    3    1    3      
   |                                               O    O    O    O    |
   |   O SG-               :  new jumper           x  L |    x L  |    |
   |   :    W1             x  remove jumper        x  2 |    x 1  |    |
   |   :         J5  J6    |  existing jumper      O    O    O    O    |
   |   O FG-                                       2    4    2    4    |
   |_____________________                        ______________________|       
   top                                           bottom

 3.  At this point, you have to decide how functional you want the drive
     active LED to be.  You will probably have noticed that the disk
     active LED is on the left front on the SMD-180 and on the right
     front on the SMD-130.  You have three choices.
  a) Forget about it and use you ears to tell you when the drive is
  b) Drill a small hole through the plastic front at the location of the
     SMD-180 LED;
  c) Unsolder the LED on the SMD-180, extend it on wires to the SMD-130
     location and epoxy it in place behind the old LED window.  I used
     clear epoxy with a small piece of silver foil as reflector to
     achieve sufficient LED brilliance.  I did not change LEDs as I
     suspect the SMD-180 LED has a far lower driving current.  To remove
     the LED, I had to remove the two screws holding the board, the two
     cables pluged in by the stepper motor, tilt the board up and use a
     solder sucker to get it out.  If you're willing to do this, you
     don't need further instructions!
 4.  Remove the three screws on the bottom of the disk drive case and
     lift off the SMD-130.  Remove the two screws holding on the RFI
     shield and slide it off to the rear.  Now slide it onto the new
     drive and put the two screws back in place.  Use a small Phillips
     screw driver (about 1/8" diam) to loosen the two screws holding on
     the plastic disk case front from the SMD-130.  They are accessable
     from the top looking vertically straight down just behind the
     plastic front.  Once the screws are completely free, gently lift the
     plastic front off the SMD-130 taking the screws along.  Look behind
     the eject button and note that it is attached by two plastic hooks
     through a rectangular hole in the metal eject lever.  Very gently
     compress the two plastic clips together, remove the plastic knob and
     push into the hole on the SMD-180 eject lever.  Install the plastic
     drive front on the SMD-180 by reversing the removal procedure.
     Screw the SMD-180 onto the case bottom using the three retaining
     screws.  Be careful to position it as far forward as possible so
     that the plastic front touches the lip on the case bottom.
 5.  Plug the two connectors from the interface board into the rear of
     the SMD-180, hook the top cover over the LED and eject button and
     lower the rear over the interface board.  Once in place, do up the
     four screws on the bottom and the SF354 is now a SF314.  Hook up and

John Hissink
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