400k floppy drive woes

[Apostrophe]

Hi all,

I'm back from a leave of absence from these forums; I stopped posting for a while following a few problems between me and certain other members here. I'm back in the hope that we can start fresh again; I'll admit that I do tend to overreact sometimes, and I'm sure that none of us wanted any of what happened to have happened.

I'm back from vacation and decided to take a shot at that Macintosh 512k's floppy drive. My original intention was to replace it along with the analog board, but after reading stories of people fixing them by removing dried grease and re-lubing, I decided to give it a go myself.

So I removed the floppy drive and followed instructions provided here to open the drive and remove the grease.

I saw a little bit of black sludge, sure enough, on the 'worm gear' thing that moves the head back and forth, but not much anywhere else. I don't have any grease-removing chemicals offhand, but that can be remedied soon. But I'm wondering if the drive was jammed or something.

My first concern was the little piece of black plastic right above the read/write head that you can move up and down once you remove the insert/eject mechanism. Is it supposed to just be a piece of circular black plastic at its tip, right above the head, or should there be something else on it?

Also, when I reassembled the insert/eject mechanism, I found that the black plastic could be oriented so that once assembled it could be either a) practically touching the read/write head, or B) one and a half centimeters above the read/write head.

So I tried inserting a floppy disk, watching carefully. When I inserted it with the black plastic oriented so that it touches the read/write head, the floppy disk wouldn't go in all the way because the black plastic wouldn't go up any further, blocking it. When I inserted it with the black plastic oriented so that it's 1.5cm above the read/write head, the floppy went in but remained about half a centimeter above the read/write head. I was under the impression that the floppy disk is supposed to 'sink' a bit, like other floppy drives. And I couldn't tell from the pictures in my link what parts of the mechanism related to 'sinking' the floppy disk.

I reassembled the 512k but I left out the floppy drive for further action. Can anyone give more specific pointers (or pictures) as to how the black plastic should be oriented, as well as what part of the mechanism relates to the 'sinking' of the disk? Those two concerns seem to be the only problems (apart from the worm gear, which I'll take care of) with that floppy drive. Can this be saved, or will I have to find a replacement?

-Apostrophe

 

[tomlee59]

It has now been several years since I last opened up a 400K drive, so my memory is foggy on certain details. But I can say with certainty that two things make direct contact with the floppy media. The head is one (of course), and the other is a piece of felt on a post (?) that pushes on the other side of the disk to ensure intimate contact of the media with the head. If the felt has been worn away or ripped off, then the disk will not make reliable contact with the head.

 

[stevep]

I have done three of these 400K drives that were stuck; all of them it was the eject lever mechanisms that were so plugged with old grease they would not move. It took several days of allowing new lubricant to penetrate the old grease and wiping the excess away before they would properly function.

 

[Apostrophe]

Oh, okay, thanks. Well, I'll track down some lubing chemicals and such and I'll give it a go on that floppy drive.

JDW recently suggested to me that I upload pics of the drive as that would be more effective than just describing my problem. I certainly agree, but I'll be a bit busy for the next week or two. But after that, I'll find a camera and photograph the drive where my questions are concerned, etc. So pictures are coming soon!

-Apostrophe

 

[trag]

I have done three of these 400K drives that were stuck; all of them it was the eject lever mechanisms that were so plugged with old grease they would not move. It took several days of allowing new lubricant to penetrate the old grease and wiping the excess away before they would properly function.

Yes, the lubricant Apple used turns to glue after a time. Back around '95 I had two 400K drive mechanisms new in the box as service parts, which I bought at UTexas's surplus auction. They were both glued stuck. And that was 14 years ago for drives that were never used.

IIRC, I used a cotton swab with alcohol to remove the old lubricant. Most of the relevant bits are on the sides of the drive where you can easily reach them. I didn't need to do any cleaning on the interior. Then I used a bit of lithium grease and one worked fine. The other one, I had sold before I realized they had this problem, and the buyer had the same issue. But he cleaned his up too and it worked as well. They were still sealed in the original packaging.

 

[tomlee59]

I'm surprised to hear that alcohol worked -- that's a bit counterintuitive. I've always used WD-40 as a solvent (NOT as a lube here). It works a treat, as the saying goes. Wipe everything clean afterwards, then re-lube gently with chassis grease of choice.