A well-known weakness of the portable IBM PS/2 models P70 and P75 is their floppy drive. Many of the drives have failed due to leaking capacitors and/or problems stemming from their vertical orientation. This adapter is designed to allow replacing a failed IBM drive with a standard PC floppy drive.
For a similar project for the less portable IBM PS/2 Model 50(Z) and Model 70, check out @TubeTimeUS's PS/2 floppy drive adapter. It was after I found his project that I had the idea to make this version for the P7X.
I designed the PCB using KiCad 5 and ordered a small batch from Aisler, of which there are still some left. Feel free to send me an email!
Apart from the PCB, you will need the following components:
| Designator | Quantity | Description |
|---|---|---|
J1 |
1 |
2x17 2.54mm shrouded pin header |
J2 |
1 |
2x17 2.54mm socket header |
J3 |
1 |
floppy power connector |
R1–R6 |
6 |
1k 0.25W 5% axial resistor |
Assembling the adapter is pretty straightforward, see the photos below. Note that in trying to keep the PCB small enough to physically fit in the P7X, I had to place the components very close together. If you use a shrouded pin header for J1, it is easy to accidentally cover some of the neighboring through-holes. In my experience, the easiest way to avoid this is to solder on the P7X-side header J1 last.
Most newer floppy drives do not need the +12V line, e.g., both of the drives I tested work with just +5V connected. It is there, however, in case some other drive needs it.
Read Louis Ohland’s P70 page for information on how to remove (and install) the floppy drive. It contains a lot of other useful information on the P70, too.
I have personally tested the adapter with the following drive models:
-
NEC FD1231H
-
TEAC FD-235HF
If you end up using this adapter (or fail to) with other drives, please let me know so I can include that information on this page.
With both drive models, I had to remove the plastic front bezel for the drive to fit. The eject button for the NEC FD1231H fits the hole in the P7X’s drive cover. It is not centered and a little too small, but it works well enough. In the case of the TEAC FD-235HF, you will have to file the eject button down a little to make it fit. @TubeTimeUS’s project above also contains an STL file for a custom eject button for the TEAC FD-235HF. I have not yet tried whether it fits the P7X.
Another option I explored is permanently converting a disk drive by soldering on a converter board. One advantage of this approach is, that the resulting converted drive is smaller than a drive with an adapter plugged in. This makes it a little easier to install. The downside is, of course, that there is no easy way to go back.
This is what a converted TEAC FD-235HF drive looks like:
And here is how it compares to the ALPS-produced IBM floppy drive:
You can find the KiCad PCB in the converter/ directory should you want to
follow this path.