Any info on aligning a floppy drive head?

[BarryB]

Had a bad disk screw my A1200 internal drive, the disk started screeching and binding and left quite a bit of residue on the heads and wouldn't read any disks. So took the drive to bits (Chinon FZ-354 I think) and tried to clean the top head but no luck so had to take it off and could then clean the gunk off, except now I need to align it as it won't read all disks 100%


I have the Commodore Floppy Test suite but need the Dysan Diagnostic Diskette which I haven't a clue on how to obtain, so is there any 'how to' guide on aligning a floppy drive?

[orange]

I did it once with ordinary diskette. its fiddly and requires patience. it might help if you got hdd to load x-copy (for eg.; I didn't). so upper head is free to move. it should be exact opposite of lower head. trick the drive into thinking it has diskette (then the heads are next to each other). use fingers to position it directly above lower head (by grabbing both heads). then try to boot..
if all fails, at least it should read diskettes it wrote (assuming its not way off)

[zipper]

http://main.aminet.net/pub/aminet/do...d/500hacks.txt
has some text for this subject (uploaded by Stedy).
And/or http://eab.abime.net/showthread.php?p=598199

[orange]

perhaps you should use some original game or software to do the alignment. iirc, there was an utility on aminet to do it, but can't remember the name. and I think it also needs 'special' diskette. edit: found it, http://aminet.net/driver/media/TrackDiskSync.lha

[BarryB]

Thanks guys, I had exactly the same brainwave as the 'X-Copy checkdisk trial and error' method and have aligned the disk so it reads various disks on the UPPER, LOWER and BOTH sides of the disk

I pushed the head back as far as it would go and nipped up the 2 screws then tapped the head so it was more or less in the center of the disk then did some gentle left/right tapping and running X-Copy CHECKDISK after each tap, if it wouldn't read the disk I loosened the screws and tapped the head forward really gently then nipped it up and repeated the left/right tapping until it read a few disks without errors then just nipped the screws up a bit more, amazing what you can do with patience!!

Would really like to know just how aligned it is or if it will cause problems down the road? I have an external drive so formatted a disk in it then read it back with X-Copy CHECKDISK in the newly 'aligned' internal drive (took 36 seconds) without any errors. I then did the opposite by formatting the disk in the 'aligned' drive and reading it back in the external drive, again without errors and took the same 36 seconds to read. Didn't have to mess with the stepper motor fortunately so that's less for me to screw up.

I tried the TrackDiskSync program but for some reason I couldn't hear any tone when reading the disk as described in the instructions? Tried DF1: to read it back but still no tone was heard, and I definitely have my Amiga sound connected to my monitors speakers!! Also tried the ACID test of loading some copy protected disks like FOFT, Killing Game Show and Venus the Flytrap which all loaded without any problems so I guess I've fluked the alignment and got it back from the dead!!

[BarryB]

I now have another drive that needs aligning but this one has not been touched yet as it's been stood for quite a few years now. It's my 2nd external drive I use, an Amitek, that uses a SONY MPF420-1 drive and has a 3 way swith for ON/OFF/Anti Virus and also has Anti Click as well. The drive has various read errors from track 0 to around 40 (mostly on the lower head) then has much better reads from then on with very few errors. I can't see any stepper motor adjust or any other adjustment other than the track 0 sensor, I think, which I've highlighted here:



The stepper motor can be loosened with 2 screws as per the link zipper gave but the stepper is secured with Torx T8 screws, same as the screws pictured above that secure the upper head, so I can't adjust that as I have no T8 driver so the only adjustment is the Track 0 sensor, so anyone have experience with this and is the best way other than the stepper adjust?

Also, I've seen a mod for this drive to make it Amiga compatible but my drive does not have this mod and still works, here's the link to the mod:

http://jope.fi/drives/mpf420-1/

and here's a pic of the same drive from my Amitek unit:



As you can see not cut track and no wire!! Also found in that link the jumpers for changing the LED from Amber to Green, so mine is now Green

[Stedy]

Barryb,

With regard to the Amitek drive, just find a PC floppy drive with the data connection on the same side as that on the little interface board. You may need to extend the power lead, that's it. I replaced the drive mechanism in my Amitek external drive maybe 10 years ago this way.

The new drive was shorter than the old so I ended up cutting and drilling the folded metal case to suit.

Ian

[BarryB]

Right, I'll do that then Ian as where I work we have plenty of PC's I can pinch a drive from and try! In the mean time I can mess about with the drive and If I cock it up it's no great loss as I already have another external drive

BTW and OT, made up one of your RGB > SCART leads the other day to try on a mates LCD TV (when he remembers brings it round that is), had to use a 68ohm resistor rather than 75ohm on the +5v pin as that's all I could find, will that cause a problem? Tried it on my 14" Goldstar portable and it worked fine but should it be 75ohm?

[BarryB]

Nope, that didn't work?

Tried 3 drives, Panasonic JU-257A607P, SONY MPF920-E and ALPS DF354N113F and all do exactly the same thing as the original drive. So it looks like it could be a damaged wire in the floppy loom or something faulty on the board?

Do these drives need modding for the Amiga beforehand though or are they plug and play?

[Stedy]

Barryb,

I checked my Amitek external drive, I fitted an Alps DFE354H090F drive and I also tried a Mitsumi FA404M and a Epson SMD300 with no mods.

I have reverse engineered the wiring of the Amitek drive, I need to redraw it using Visio before publishing it. If you are not careful wires under the IDC connector can come loose.

With regard to the SCART cable, a 68 ohm resistor will be fine. From memory, 20% tolerance is fine. Will add some limits to the next drawing update.

[BarryB]

Cheers for the info on the RGB lead.

Regards the Amitek, I've checked the wiring is sound from all pins on the IDC to the 23pin floppy connector and there are no shorts, the diode on the board is fine as is the 680k resistor, not sure of the 2 caps or if the PEEL IC is duff? The SIL resistor pack measures 500ohms if probe on pin 1 and then all other 9 pins tested so it's 'commoned' I think. Can't figure out why 3 drives are doing the same thing other than the PEEL IC must be faulty??

[BarryB]

Just a quick update, the Amitek drive has decided to work now? I put it in my other external drive case and used it's interface but it kept saying there was no disk in the drive until I popped the disk out and back in. Also, had to adjust the Track 0 sensor so it read a whole disk without errors but still had to pop the disk out/back in for it to recognise it.

After putting my other eternal drive back together and then the Amitek drive I'm now back to 2 working external drives, so either the Amitek is just being stupid or there is a damaged wire in the cable that's intermittently breaking it's connection?

[brufnus]

Ha ha, this is crazy! :-D

I just had an external CDTV-drive, which failed because I was trying to salvage a sound sampler diskette, of which I never managed to make a backup. It's from Danish Amitech/Alcotini and pretty hard to find nowadays, or at least I thought so.

However, partially because of some mistakes I made myself, the drive wouldn't read any of my diskettes afterwards... so I started out by cleaning and lubricating it thoroughly, but to no avail... alas! c".)
I also discovered though, that it was able to write and read it's own disks - so, a calibration problem "only", phew! B-)
It did read a few times, but mostly it was a failure... until I discovered this thread. I downloaded the TrackDiskSync program mentioned here, created a sync disk and quickly discovered that I could make it read a WB disk just by pressing it in a certain way around the stepper motor and the head assembly.

In the end I only had to loosen the fork screw at the stepper motor shaft, try and bend the fork a little, and after perhaps 5 or 10 minutes it worked flawlessly, voila!! :-D
Now I've tried adf'ing Kefrens Desert Dream disk 1 and read it from my other drive, and everything is in working order again.

Thanks for the tip!

P.S. Oh, by the way - I actually found an adf with the sound sampler program on a German website. Thanks for that as well! c",)