Mitsumi D359T3 read ok but often fails write operations

[Turrican_3]

Hey there,

got a stroke of luck and found two old PC drives that can be modified to become Amiga compatibile.

One of them though, a Mitsumi D359T3, often shows issues while writing. That is, the vast majority of the tracks are ok, but a few of them are not. Happens with both AmigaOS builtin format and with XCopy format with verify too.

I'm quite confident it's not the Amiga nor the cable nor the media, as the exact same setup (and floppies) works flawlessly with the second unit, a Teac FD-235HF 5165 for the record.

I've also cleaned heads and connector with IPA, plus applied a little bit of lubrificant on the step motor rail to be on the safe side.

Disks formatted with the Teac unit also show no errors at all when read on the Mitsumi.

Any suggestions?

[Leon Besson]

Have you checked the calibration of the read write side? Worth getting hold of Amitestkit (Amiga TestKit) as this will show you if the heads are calibrated.

[Turrican_3]

Yes checked with Amiga Test Kit and drive shows no issues.

There seems to be one significant (?) difference that I'm noticing though.

Formatting via Workbench (3.1, paired with a same version stock Kickstart) basically always give errors.

Formatting with Xcopy and then running the builtin checkdisk function leads to the same results... except it doesn't if I run the erase function beforehand?!

Does anybody know the exact purpose of this function? I'd guess it basically wipes the disk out of any Amiga-meaningful data (an "erased" disk shows DOS:??? when inserted), but I wonder if this is a reasonable explaination.