EIII Booting with no end

[Emax]

Hello:
I've seen another topic which is very similar, but not the same:

My EIII keeps stuck while searching for SCSI devices (Floppy , then SCSI 1,2,3, etc) with no end. HD runs and it seems to be ok. I checked different jumper configurations and SCSI numbers, with no success.

I've tried to boot from floppy (I got the original OS 2.42 on a DS DD eIII formatted disk), but altough the floppy drive starts to turn, there is not that classic head noise, and nothing seems to happen.

Re-seated some of the boards (not the chips).

Any suggestion?
Thank you.

[Emax]

Update:

Tested three different working floppy drives. All powers up and spin, but head is not working.
Put different hard disk, just for check if the Floppy works fine, no success.

Replaced the SCSI chip, no success.

Checked PSU voltages, all fine.

Suspecting about the Floppy Disk controller chip...

[vds242]

Changing the ribboncable of the floppy drive is another idea.

Chris

[Emax]

Thanks for the suggestion. I forgot to say that I had already tested it too.

What I noticed is floppy drive has to be reverse-wired (connector upside down) for running. If I put the ribbon in the right position (red wire to pin #1) it doesn't spin at all, and the EIII won't even start the boot process.

[Emax]

it would be nice if someone can confirm if this "reversed" ribbon is needed for the normal operation.