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|*| ST DISK DRIVE CONVERSION |*|
|*| SINGLE TO DOUBLE SIDED |*|
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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
read/write.
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
active;
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
enjoy.