In a recent Amiga 500 Plus haul I managed to obtain a boxed Rotec RF332C external floppy drive, it even can with the original invoice and receipt! It was dirty like everything else, but more importantly it was faulty. Listening to it running the head was moving but it didn’t sound like the drive was spinning. In addition one of the rubber feet were missing. So, on with the repair!
First the external parts, I removed the remaining three feet from the case and cleaned up the remaining glue.
The feet appear to be the same type as the Amiga, just in black. These are 3M Bumpon SJ5012. I needed to replace the Amiga 500 Plus feet so I ordered new feet for this at the same time from RetroBench.
Now to repair the insides. Those 6 screws need to come off. Then the upper shell slides forward to reveal the PCB. You need to lift this up a bit and then slide it the other way to get the drive out. The two screw holes at the back of the case prevent you from sliding it forward all the way. There is one screw to remove the lid of the floppy drive (back right as the drive faces you) and then you can carefully pry off the lid. Once inside this is what it looks like.
The drive itself is actually a Citizen UODC-12A which Rotec built a case and controller board around. It uses a rubber belt to spin the disk, a rubber belt that is likely nearly 30 years old, I suspected that this was not in good condition. I touched the belt with some tweezers and it immediately disintegrated.
That would explain why it isn’t spinning! Luckily new belts are easy to obtain. I ordered one from DataServe Retro which came quite quickly in the post. It is a little fiddly fitting the new belt, first you remove the two screws holding the drive motor bracket to the top, be careful when removing it as there there are tiny wires attached to the motor that cannot be removed.
Next up the belt needs feeding over the big wheel, around the right (as the drive faces you) of the small pulley and to where the drive motor sits. You can then carefully slip the belt onto the drive motor as you reseat it back into place. The finished result should look like this.
Next up a quick head clean. I used isopropyl alcohol on a cotton bud to gently wipe any potential dust and other dirt from the top and bottom drive heads. You can see the small white rectangle with black line of the bottom head below, you will be able to lift the plastic arm of the top head slightly to get better access to that.
After this the entire drive was reassembled. Plugged into a working Amiga and… success! It was reading disks perfectly!
In summary, if you ever obtain a Rotec drive chances are the belt has failed with age, replace this, clean it up and you should be good to go!