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axeman

Atari ST 5.25" External Drive Issue

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Hi,

 

I've got an external drive which refuses to read or format a floppy disk.

 

I've dismantled it and cleaned the mechanics and the head.

 

I've manually moved the head to track 80 then turned on the drive and then the ST and the head moves to track 0.

 

The disk spins and the drive head moves from track 0 to track 1 when trying to format moves but no further and the format responds with disk may be unreadable error - abort cancel.  

 

The disk worked ok on a C64 and I've tried switching to 40 and 80 tracks and get the same result on the ST.

 

Should the head move to track 80 then track 0 when formatting ?

 

Is there a disk drive diagnostic utility which tests drive head movement i.e can I specify a track and test the head moves correctly?

 

Thanks in advance  

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I have an external 5 1/4" drive too that also refuses to read/write/format, I believe this drive was new

when I purchased it, I managed to get it to almost format a disk, it went the full 80 tracks but failed

when trying to write the FAT to the disk.

 

I also noticed it wouldn't even try to format some disks with the same error you are getting.

 

Found this Diag tool.

https://www.exxoshost.co.uk/forum/viewtopic.php?t=1905

 

There's a link to his store, £25 for one.

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Thanks TGB I only just got one of these and didn't realise all it can do also had the jumpers set wrong as was previously testing an old 520ST and I'm testing with STE so the menu wasn't coming up.

 

Tried testing and the head moves all the way to both ends so that was good but still getting read fail error.

 

Retried disk in C64 and it works fine.

 

Tried back in ST and tried formatting with 40 and 80 track mode but still fails on formatting first track ??

 

 

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Woohoo! it works. There was a bit of friction noise on track 0 but non after track 20 so disassembled the mechanics , cleaned, reassembled and it works and the friction sound is reduced.

 

Thanks for your help guys

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Out of curiosity... what drive?

 

I know of 2... the ST version of the "Indus GT" and the PCF551.

 

 

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On 8/2/2021 at 11:30 AM, axeman said:

Woohoo! it works.

Glad you managed to sort it, I think my problem may be the formatter/controller chip which unfortunately is

not socketed, I have 2 1770 chips I can use to test but will have to remove the 1772 chip (carefully) first, the

only difference between the 1772 and the 1770 is the step rate which is much slower in the 1770.

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On 7/31/2021 at 2:21 PM, axeman said:

I've got an external drive which refuses to read or format a floppy disk.

I've dismantled it and cleaned the mechanics and the head.

I've manually moved the head to track 80 then turned on the drive and then the ST and the head moves to track 0.

The disk spins and the drive head moves from track 0 to track 1 when trying to format moves but no further and the format responds with disk may be unreadable error - abort cancel. 

The disk worked ok on a C64 and I've tried switching to 40 and 80 tracks and get the same result on the ST.

 

I've never seen an ST drive with a 40/80 tracks switch. Would  you mind opening the drive and take some pics? I would assume it has some logic to enable or disable double step. Would be interesting to see how this is implemented.

 

19 hours ago, Tillek said:

Out of curiosity... what drive?

I know of 2... the ST version of the "Indus GT" and the PCF551.

 

There were several 5.25 drives for the ST. I remember I.B. and Cumana.

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13 hours ago, ijor said:

I've never seen an ST drive with a 40/80 tracks switch.

My 5 1/4 floppy drive also has a 40/80 track switch, inside it's a TEAC drive

with Schugart connectors and an interface board to convert the ST connections.

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13 hours ago, TGB1718 said:

My 5 1/4 floppy drive also has a 40/80 track switch, inside it's a TEAC drive

with Schugart connectors and an interface board to convert the ST connections.

Would you mind taking a couple of pictures of the interface board and how the switch is connected? Should have more logic than a "simple" ST drive without a 40/80 switch.

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