Hi Guys,
On the infamous “zero track alignment” issue with the floppy drives…
I fixed many drives in the past with the most usual “trial and error”, luck-driven and unnerving approach.
This time I opted for something more structured, which has proven to be rather successful (read: not much time spent).
Pre condition: you need to have a “reference drive”, realistically one with factory settings and still working.
You will use it for creating the reference floppy disk.
Drive to fix: cleaned up and lubricated, as per above instructions.
Now, what you have to do is to realign the position of the optical sensor that detects when the pick up head is in the right initial position.
Unfortunately, catching the correlation between changed position of the sensor and the actual position of the pick up is impossible, as there’s not visual aid.
So, the trick is to create a reference system which can drive you in the process.
Put the drive under a top light, means that you will have a shiny line caused by the reflection of the round shaft.
With a fine tip permanent marker, draw a tiny dot, right on top of the shiny line.
Now here’s the key information:
- when you eject the disk, the stepper motor is always receiving the same number of impulses, corresponding to an integer number of revolutions. This means you can make your dot with the marker after the disk has been ejected, which is much easier. You will see when you insert it and the pick up is brought back to the initial position that the mark will get in the exact same angular position.
- If you try to format the disk, you can easily count 10 discrete steps per each revolution. Means that each rotation of the shaft of 36 deg corresponds to one track in the floppy (0.115 mm).
Procedure I have used.
- loosen up the screw that keeps the optical sensor in place.
- Take the sensor all the way back: you will start from there.
- Now the difficult part: tighten the screw just enough to keep the assembly stable, but allow some movement when gently forced, for example when you gently tap the sensor with a screw driver or similar. You want to imperceptibly move it forward, literally one (motor) step at a time.
- Of course, you have to adjust the position after ejecting the disk, then re-insert it and see if the shaft is stopping always in the same angular position or not.
- If not, you should be able to judge by how many angular steps the position of the pick up has changed.
- Proceed one step at time, until a known good floppy is read and mounted.
- In the case of the last drive, I had to allow four rotational steps from the very end for matching the zero track of the good floppy.
On the infamous “zero track alignment” issue with the floppy drives…
I fixed many drives in the past with the most usual “trial and error”, luck-driven and unnerving approach.
This time I opted for something more structured, which has proven to be rather successful (read: not much time spent).
Pre condition: you need to have a “reference drive”, realistically one with factory settings and still working.
You will use it for creating the reference floppy disk.
Drive to fix: cleaned up and lubricated, as per above instructions.
Now, what you have to do is to realign the position of the optical sensor that detects when the pick up head is in the right initial position.
Unfortunately, catching the correlation between changed position of the sensor and the actual position of the pick up is impossible, as there’s not visual aid.
So, the trick is to create a reference system which can drive you in the process.
Put the drive under a top light, means that you will have a shiny line caused by the reflection of the round shaft.
With a fine tip permanent marker, draw a tiny dot, right on top of the shiny line.
Now here’s the key information:
- when you eject the disk, the stepper motor is always receiving the same number of impulses, corresponding to an integer number of revolutions. This means you can make your dot with the marker after the disk has been ejected, which is much easier. You will see when you insert it and the pick up is brought back to the initial position that the mark will get in the exact same angular position.
- If you try to format the disk, you can easily count 10 discrete steps per each revolution. Means that each rotation of the shaft of 36 deg corresponds to one track in the floppy (0.115 mm).
Procedure I have used.
- loosen up the screw that keeps the optical sensor in place.
- Take the sensor all the way back: you will start from there.
- Now the difficult part: tighten the screw just enough to keep the assembly stable, but allow some movement when gently forced, for example when you gently tap the sensor with a screw driver or similar. You want to imperceptibly move it forward, literally one (motor) step at a time.
- Of course, you have to adjust the position after ejecting the disk, then re-insert it and see if the shaft is stopping always in the same angular position or not.
- If not, you should be able to judge by how many angular steps the position of the pick up has changed.
- Proceed one step at time, until a known good floppy is read and mounted.
- In the case of the last drive, I had to allow four rotational steps from the very end for matching the zero track of the good floppy.
