Calibrating a 3.5" floppy drive

[hjalfi]

I took out the wrong screw in a NC200 3.5" floppy drive, while trying to figure out how to change the belt, and realised too late that I'd ruined the track alignment.

So I gather that the simplest way to fix this is to place a known good disk in the drive (which I have), continuously run a program which reads all the sector IDs from the disk (which I can write), and adjust the head position by tiny amounts until they all read correctly. However, a 3.5" drive has 0.189mm track spacing, which is very very small. I would need to design and 3D print some kind of lever-based tool to allow me to adjust the position by very small amounts. Even then, operating the drive will be tricky as it doesn't use a standard pinout --- it's a Citizen V1DC-65B laptop drive with a all-in-one flex cable containing power and data, so it would need a breakout board of some description.

Is this something that it's actually feasible to do, or should I just give up now and get a Gotek? (I would much rather stick with really floppies, TBH.) (It might also be possible to find replacement drives with the same pinout but I've had no luck so far.)

 

[Chuck(G)]

Dunno--I work with the 1/3 height (25.4 mm) 3.5" drives a lot and on most, you basically slightly loosen the screws holding the stepper in place and gently rotate it slightly, then tighten the screws back up. Teac drives even have a little tab attached to the stepper body so you can see where you are. I can easily tweak a drive by a quarter-track without too much effort.

Of course, a proper alignment disk helps a lot.

 

[hjalfi]

I'm not sure this drive has such an adjustment. The entire head assembly is mounted to the drive chassis by two screws in oval holes --- I loosen the screws and slide the head mechanism backwards and forwards. The motor itself doesn't seem to have any options to adjust it. So, half a track of adjustment means loosening the screws, moving it by 0.1mm and doing them up again. I'll have to double check, though.

 

[my03]

Hi Hjalfi,

just saw this thread now. Did you manage in the end?

I'm about to do the same thing (Mitsumi d353f2 in my case) that has the same oval/slide/screws setup.