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


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


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

  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.

  3. Here's a pic of the upper shield; made some small cuts and folded the metal:

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

  5. Your READY signal is wrong and didn't work!

    1. Sorry about that m8! If you provide me the right place to find READY signal on the specific drive model, I'll update the blog post };-P

    2. It seems these Teac drives have no READY signal:

  6. This is the right READY signal:


  7. PJay, your hack can't be applied on the C291 U5 because you hacked a B391 with other floppy-mainboard !! So your hack is maybe not working here and as Elgens floppydrive is still working he has surely found the right ready signal!

    Someone has to confirm your method is working on the C291 U5 too.

    Btw. there are different mainboards out there with same drive model type! To go sure that these hacks are working, everything has to match.

  8. I have tried it on many drives with same board layout and I'm pretty sure that it works =)

  9. I just want to say that Elgen's mod is working with a Teac FD-235HF C110-U5 too because it has the same controller IC. I've modded it succesfully. Before that i tried PJay's ready-signal and it didn't worked! Elgen's mod is working! It is not the real ready signal, that's true, but...everything is working so far except if you want to copy from DS0 to DS1 with Xcopy. Format and copy with same drive as DS0 is working.

    1. Thnx for doing the investigation and getting back on the topic <3
      I'm not very active atm. Hope to get back on repairing again some time again };-P
      Love <3
      };-P Elgen