How to fix a 5.25 floppy drive?

[SeanSheehan]

My old drive is not reading any floppies. I have cleaned the heads. A floppy will spin away happily but this is the only response to a *CAT input.
Any suggestions?

 

[Istarian]

Execution of a (CAT)ALOG command, will naturally involve reading from the disk in the drive to see what exactly is stored on it.

That might involve locating track zero if the drive hardware is relatively simple and operated directly by software.

Does it sound like it's doing anything other than spinning? Like moving the head inward or outward?

After the drive stops spinning the disk, does the software (BASIC or maybe some kind of ROM operating system) report any kind of error or problem? Or does it just return to a prompt without any output?

 

[SeanSheehan]

Thank you.

I have removed the metal casing from the twin drive unit (0 and 1) and, while the head used to move forward, it now remains stuck (at track zero, I guess).

No error message appears and when I stop the spinning (by lifting the handle on drive 0) -- otherwise I think it would spin for ever -- there is no output.

Error messages along the lines of 'disc error 18' or 'disc error 50' used to appear but now the drive head seems unable to get past the first track.

To confuse matters, when I try to run the same disc in drive 1, *cat does return a list of the file names) but shift+break has no effect.

(The computer is a BBC Master 512).

 

[Istarian]

If I understand what I am reading, shift+break should tell the system to try booting from the disk in drive 0.

Booting from Drive 1 apparently requires extra steps and typing some commands unless you have some way (physical switch?) to make it appear as Drive 0.

Good to know that at least one of your drives is in working order, at least for now.

If the read/write head isn't moving at all, perhaps the drive does not think there is a disk in the drive? The lack of any output from the CAT command might also point in that direction.

You might also look for any signs that the head is physically stuck in place or obstructed as well as the possibility of a mechanical failure of some sort.

Spinning the disk is probably triggered by closing the latch/door and would normally be followed by an attempt to identify the disk inserted and check for a proper filesystem.

P.S.

Disk Fault (Error?) 18 might indicate some problem related to 40/8 track disks and which the drive was expecting to work with.

 

[Gary C]

If you move the head manually before you power it up, does it then step back to track 0 ?

Need to check a few things

If it won't step, need to check pulses at pin 20
Check that the track zero input is high when the head steps back to 0
Check index pulses are being sent whenever the disk is rotating, check pin 8

What drive is it ?

When you move the floppy to drive 1 it reads it ? so the disk itself is ok, I bet from the symptoms your not getting the track 0 indication.