External Roctec RF382C-A floppy drive - not working

[quiet1]

Thanks for the comprehensive posts about this drive solarmon,

I now have one of these dreadful drives, hoping it would just be a 'belt' issue but, nope, this one behaves exactly as description by the following users in this thread:

• TjLaZer
• Tumppi

I have also replaced the caps (they were dodgy looking).

So just like the other users' drives, you can push the heads to track 0 and it will read through a disk, even boot a disk (until the heads need to go backwards; causing a read error).

just like TjLaZer's youtube video. The drive by itself seeks the wrong way to find track 0. It ends up at track 79. (see his video @ 1:37 where he moves the heads back [ Show youtube player ])

I am running Amiga Test Kit, a signal test triggers the drive heads move to 79. if the heads are not manually pushed to track 0 you can hear it trying to go beyond 79 on the signal test.

It is as though the heads won't move backwards, but get this:

I can start a head calibration test (with heads manually pushed to track 0).

it will read upper & lower 11/11, I can work through each track up to 79 and it is fine.. going over 79 does not make it seek back to zero, instead it tries to go beyond 79 and then it is all out of sync (but 11/11 on every track up until this point).

The interesting observation is that I can go backwards -1 track at a time ONLY if the track is NOT sat on a multiple of 4. so for example I can move from 1 to 3 and back again. and I can go from 13 to 15 and back to 13 freely / many times. however if I try to go backwards from tracks 4, 8, 12, ... it does not adjust the track position at all. even with follow up attempts, the drive heads remain still. While Amiga Test Kit is thinking it is moving backwards, the drive doesn't budge (until it is phyically off the 4x track).

If I am on a track where I *can* move backwards, such as track 13, when I attempt to go back -10, the result is that the physical drive heads only moves back -1 track (again Amiga Test Kit gets out of sync).

What could be the cause of this, bad logic? could a controller / IC be checked? could it be the stepper motor itself?

It seems its not just me with this issue