Atari ST Floppy Drive Repaired

[GadgetUK]

Hi,

 

Not sure if anyone's covered this before but I wanted to share this info in the hope it might help someone else.

 

Just got an STe (with faulty FDD), and last night stripped it down to add A9 RAM switch and dual TOS, as well as to take the FDD out and see if I could fix the drive.

 

Cleaned the heads with isoprop - no difference. Was ready to accept defeat when I decided to have a good look at the mechanics as well as the logic PCB. Noticed that this model has 2 surface mounted electrolytic caps - bang, it hit me this is very likely the problem.

 

Swapped out the 4.7uF one that seems to affect rotation timing. Now works perfectly.

 

If you have a faulty FDD, clean the heads, clean the rotary assembly and oil, but check for surface mounted electrolytic caps and replace as required.

 

Model in my STe is a Sony MPF110-03

 

Edit: this is likely the same on some amiga drives as well,

Edited February 14, 2013 by GadgetUK

[GadgetUK]

The other cap on drive that I've not yet replaced (on order) is 47uF.

 

Here are the two pictures showing the replaced cap, and the one I still want to replace that sits on the power input.

 

 

[Zogging Hell]

Ah excellent, I have a couple of duff ones of this drive, my electronics knowledge doesn't run to working out problems like this so this is quite useful, thanks for posting!

[GadgetUK]

Excellent, hope you can fix them! Floppy drives often get binned when a proper clean, de-magnetise heads, and replacement of failed caps or motors can fix them. I wonder how many salvageable drives have been binned over the years =|

[Brith]

Hi,

 

First time i see on the internet a way to fix an ST floppy drive.

I've got 2 faulty drives : 2 Sony. 1 MPF110-03 and 1 MFD-11W-5DU.

 

I'm really looking forward to have time to change the 4.7uF cap.

How did you remove the original one (iron for sure, but can i have more details, the cap seems over the lead ) ? Did you need access to the other side of the pcb ?

Is there a + and - to follow, on the 4.7uF cap ?

 

Why do you want to change the 47uF cap, as your drive is now fully fonctionnal ?

 

Thanks for posting too !

[GadgetUK]

Twist the old ones off, dont bend them or you will lift the tracks.

 

The other one smooths the input power, so the drive will work but the cap does need replacing really or you can get spikes from the PSU that cause bad reads / writes or seeks etc. Yes, there'a plus and minus - check on the PCB and look at the cap before you twist it off!

 

EDIT: Also, don't forget to clean the heads whilst you are there. Just dab a cotton ear bud in alchohol and rub each surface of the heads.

Edited February 18, 2013 by GadgetUK

[edumanga]

Hi,

I just saw this, and since my 1040 st floppy drive is dead (long button one) and I really don't want to cut the case of my atari, I was wondering if someone could point me to a tutorial so i can try to salvage the drive.

Thanks!

[GadgetUK]

Firstly, what make and model drive is it? Have you cleaned the heads yet?

[Zogging Hell]

Hi,

I just saw this, and since my 1040 st floppy drive is dead (long button one) and I really don't want to cut the case of my atari, I was wondering if someone could point me to a tutorial so i can try to salvage the drive.

Thanks!

 

A lot of the earlier ST drives use a old school drive belt (like a rubber band) to turn the platter, this has a tendancy to rot and either snap or become so loose it can't turn the drive, so it might be worth checking this first as it is quite an easy fix.

[eeun]

I've fixed many LCD monitors and a few PC motherboards that were suffering from bad caps, but it never would have occurred to me that a floppy drive might be faulty from the same cause.

Thanks for posting this, Gadget!

[carmel_andrews]

GadgetUK, you could just have easily used an internal amiga DD instead (just reverse the data cable at the drive end)

 

Only thing is you'll have to either remove the eject button from the amiga DD or cut a hole big enough where the drive sites on the ST casing to cover the amiga dd's eject button or just leave the case off (not a good idea)

[GadgetUK]

You know caps are a pain really, they fail a lot more than other components that's for sure. I also believe that old DRAM in some of these systems is failing due to internal refresh caps. Had an Amiga 500 recently where most of the DRAM was faulty (like 12 out of 16 chips with refresh problems), which I find hard to believe... But I understand that these old DRAM chips use capacitance as refresh circuitry. That said they are probably not electrolytic in the DRAM fab.

 

Zogginghells post about belts is also a very good point - these are the primary failure point in those old drives. Thankfully none of my drives use belts.

Edited August 9, 2013 by GadgetUK

[GadgetUK]

GadgetUK, you could just have easily used an internal amiga DD instead (just reverse the data cable at the drive end)

 

Only thing is you'll have to either remove the eject button from the amiga DD or cut a hole big enough where the drive sites on the ST casing to cover the amiga dd's eject button or just leave the case off (not a good idea)

 

I thought the 500 had a different select and refresh circuitry? Amigas use shugart, I didn't think that would work without modification? PC drives work without much change from what I remember but even those I think needed a different drive select jumper. EDIT: I think you are right, it just won't work the other way around properly - ie. ST drive in Amiga.

 

Ahhh, I remember the days when CPC in Preston used to sell all the spares for Atari and Commodore. TEAC drives were pretty common replacements, and they had a model that I am sure worked with the Amiga or ST and was configured with jumpers, although I might be wrong because the buttons were obviously different - I might be confused with the PC / ST TEAC they sold.

Edited August 9, 2013 by GadgetUK

[carmel_andrews]

Dunno about the A500 internal DD, the one from the a600 does work though and i noticed that the a1200 uses the same mech as the a600 so the a1200 internal DD should work also

 

I'm just going by a little experiment i tried a few years ago (with the a600's internal DD) after my ST int. DD didn't like formatting any disks and i could'nt be bothered with trying to find a new internal DD (hence the little experiment)

[joedredd]

I recently bought a 520STFM, my first Atari (I've always been an Amiga guy)

Unfortunately the floppy drive would not read disks, it would go throughs the motions, spin up, head move, but just boot to TOS.

I discovered this thread through a Google search and sent the wife out to Maplns for some caps for £1.31. Swapped them both out on this Sony drive and it now works perfectly.

Thanks guys!

[GadgetUK]

That's great news!!! It's fantastic when an old FDD can be salvaged =)

[joedredd]

That's great news!!! It's fantastic when an old FDD can be salvaged =)

Even better when it's fixed for £1.31!

Next stop - 16 x DRAM chips onto the board.

[GadgetUK]

Excellent! Just remember to install sockets, don't be soldering chips directly onto the motherboard!!! And assuming you are adding the additional 512Kb, don't forget the 3 (I think) resistors that are required.

 

I've just received a couple of 16Mhz 68000 CPUs that I am going to install in my STFM and STe, with switch to toggle 8/16Mhz, but I've got to unsolder the 68000 in the STFM before I start - not looking forward to that lol

[RodLightning]

My 520STFM is in the same shape. Fortunately, I kept the original floppy drive and didn't cut the case when I put in a standard replacement. I have been ejecting disks by sticking a ball pin in through the button hole. I will add your technique to my long to-do project list. Thanks for sharing your success! I'm glad I never throw away old parts.

[joedredd]

Excellent! Just remember to install sockets, don't be soldering chips directly onto the motherboard!!! And assuming you are adding the additional 512Kb, don't forget the 3 (I think) resistors that are required.

I've just received a couple of 16Mhz 68000 CPUs that I am going to install in my STFM and STe, with switch to toggle 8/16Mhz, but I've got to unsolder the 68000 in the STFM before I start - not looking forward to that lol

Heh, way ahead of you. I was thinking to get these?

http://uk.farnell.com/te-connectivity-amp/1-390261-4/socket-ic-dil-0-3-16way/dp/1101347

 

Good luck with the processor! Sounds like a fun one.

[Zap!]

A lot of the earlier ST drives use a old school drive belt (like a rubber band) to turn the platter, this has a tendancy to rot and either snap or become so loose it can't turn the drive, so it might be worth checking this first as it is quite an easy fix.

 

I just took an SF354 that I'm trying to save apart. Black band is snapped. So what do I replace it with, a regular rubber band? What size? How tight?

Edited October 5, 2014 by Zap!

[Zogging Hell]

 

I just took an SF354 that I'm trying to save apart. Black band is snapped. So what do I replace it with, a regular rubber band? What size? How tight?

 

Rubber bands aren't usually much cop as they tend to stretch and slip, causing the speed of rotation to go up and down as the band slips (or comes off). If you could find one that was fairly rigid and the right size then it might work... however, this guy (below) on ebay sells replacements. I've brought one in the past and can confirm they work. Say he posts worldwide and considering the price it is probably better than hunting through that rubber band collection..

 

http://www.ebay.co.uk/itm/ATARI-ST-REPLACEMENT-FLOPPY-DISK-DRIVE-BELT-BRAND-NEW-/320721362657?pt=UK_VG_Replacement_Parts_Tools&hash=item4aac7b9ee1

[Zap!]

 

Rubber bands aren't usually much cop as they tend to stretch and slip, causing the speed of rotation to go up and down as the band slips (or comes off). If you could find one that was fairly rigid and the right size then it might work... however, this guy (below) on ebay sells replacements. I've brought one in the past and can confirm they work. Say he posts worldwide and considering the price it is probably better than hunting through that rubber band collection..

 

http://www.ebay.co.uk/itm/ATARI-ST-REPLACEMENT-FLOPPY-DISK-DRIVE-BELT-BRAND-NEW-/320721362657?pt=UK_VG_Replacement_Parts_Tools&hash=item4aac7b9ee1

 

I got two SM354's from eBay for $30 shipped, one black, one off-white/grey. Both were dusty looking with scuff marks. Seller said he hadn't tested them in years. Thank you for the link, I'm going to order three from him (one for a backup). On the white one, I washed the plastic case with bleach and soap, and then cleaned the head. Except for the yellowing on the front, it looks brand new. Can't wait to test it out. I really think they will work.

[Marc Oberhäuser]

 

I got two SM354's from eBay for $30 shipped, one black, one off-white/grey. Both were dusty looking with scuff marks. Seller said he hadn't tested them in years. Thank you for the link, I'm going to order three from him (one for a backup). On the white one, I washed the plastic case with bleach and soap, and then cleaned the head. Except for the yellowing on the front, it looks brand new. Can't wait to test it out. I really think they will work.

 

Anyone knows if the belt in a SM314 is the same? I have 2 1040s with disk drive failure (won't spin anymore).

[Zogging Hell]

I'm not sure. It's possible I suppose that early SF314 drives also use a belt. It's pretty easy to open them up and have a look, if the belt has broken then you'll find it's black shrivelled remains inside. If not then it might be worth looking at changing the capacitors, as in Gadgets fix, although it is probably a different model.