About me

My photo
Vanløse, Copenhagen, Denmark
Mathematician. Working programmer/system developer. Nerd. Married. Father of 3.

9.10.12

Modding a TEAC FD-235 C291-U5 FDD for Amiga use

The floppy drive in my Amiga A600HD had died, and as I'm going a bit miggy-crazy atm I decided to try modding a PC-floppy drive. An old TEAC-drive (model: FD-235 C291-U5) was kindly donated to me by the hardware-guy at work };-P

I did a bit of googling and found that when modding a PC floppy drive for Amiga use, there are 3 things to be done:

  1. Change the device id from DS1 to DS0
  2. Route DiscChangeSignal to pin 2
  3. Route Ready signal to pin 34

Here is first a picture of the unmodded controller PCB


For 1):
Locate the 3 solderpads marked DS0 and DS1 (marked with red box in the last pic below). Desolder the 0Ohm SMD resistor from DS1, turn it 90deg and solder it at DS0 instead.

For 2):
Now, for PC use, the DiscChange signal sits on pin 34, but miggy needs it on pin 2, so we need to reroute it. If you follow the trace from pin 34, you'll see that it ends at pin 1 on the square shaped IC. So solder a wire from pin 1 on the IC to pin 2 on the connector; I used the lower solderpad of S4 (marked with 2 blue boxes in the last pic below) instead.

For 3):
As the last thing, we need the Ready signal at pin 34. As this pin is currently connected to DiscChange, we need to cut the trace. I've cut it at the pink circle in the pic below, but any place will do.
And now comes the only tricky part of this mod. As the PC floppy pinout doesn't have the Ready signal, we must try to locate it ourselfs.
Now it's a known fact, that the DiscVerify in X-Copy, only works, if the Ready signal is present. So I soldered a long wire to pin 34 (the pic below) and then tried running verify, with the other end pressed against the different pads marked with S<number>. When connected to the left pad of S6 (the yellow box in the last pic below), the verify ran. So soldered the wire on there, and tried some games, that I know needs the Ready signal; and they ran too.


So routed the wires a bit nicer, and the mod was a succes.
(Please disregard the wire marked with a pink box. It's just there because i suck at SMD soldering and managed to rip a solderpad including some of the trace off };-S)


A final word:
Now there IS a risk, that I haven't found the right Ready signal; I'm fully aware of this; and should you do this mod, you should too.
But I've used this drive for 2 weeks now, and it works fine. };-P

4 comments:

  1. You are awesome. How well did the PC FDD fit mechanically into the Amiga case?

    ReplyDelete
  2. The drive in general has the same dimensions as the original A600 FD-drive. However I had to cut away a small bit of the upper shield to be able to close the case again. Also the eject button is a bit too small.

    ReplyDelete
  3. Here's a pic of the upper shield; made some small cuts and folded the metal:
    http://s1189.photobucket.com/albums/z437/ElgenDK/TEAC_FD-235_C291-U5/?action=view¤t=5B30F028-25FF-41C3-A590-3817A96C8D28-5368-0000041472451AF4.jpg&evt=user_media_share

    ReplyDelete
  4. And thnx for the kind words btw };-P

    ReplyDelete