800k drive won’t spin

[Crutch]

So a while ago I bought an Apple 3.5 drive (these are the external 800k drives in Snow White that work on Macs and the Apple IIgs, and can read 800k disks on 64k ROM Macs without the HD20 INIT installed) in beautiful condition.  Unfortunately it doesn’t work - it wants to initialize every disk.  I opened it up and realized the drive wouldn’t spin, so I tore out the drive mechanism (“Drive One”) and replaced it with a known-good 800k drive (“Drive Two”) I’d salvaged from a Plus which I connected to the Apple 3.5 drive mainboard.  It seemed to work but then, after a couple tests, Drive Two wouldn’t spin either (at startup time, it detects a disk, then won’t spin so presumably can’t read it, then ejects the disk as bad).  So I pulled Drive Two out of the Apple 3.5 drive and put it into a known-good Plus ... and it still won’t spin!  (Drive One won’t either.).  It seems like my Apple 3.5 drive is capable of ruining perfectly good floppy mechanisms!  Anyway, three questions ...

1.  Anybody seen such a thing happen?

2.  Anyone know how to fix an 800k drive that won’t spin?  (Yes, I have lubed and cleaned the drives, and cleaned the heads ... not that it should matter.)

3.  Any ideas if this Apple 3.5 drive can be salvaged somehow?

Thanks for any ideas, this one has me stumped.

 

[waynestewart]

What's the model number on the drive case?

 

[Crutch]

Not sure this is the model number but it says:

MFD-51W-10 (last digit might be a D)

30002602

 

[waynestewart]

Ok but I  was meaning the case which would likely be one of these numbers A2M2053, M0131, A9M0106, G7287

 

[Crutch]

Oh sorry you mean the 3.5 drive case. That’s an A9M0106

 

[Crutch]

Just following up on this in case anyone has any ideas. I am now the proud owner of TWO 800k drive mechanisms that, no matter what Mac I connect them to, won’t spin at all ... on startup they’ll just eject any disk inserted into them without even trying to spin at all. (They eject perfectly...).  Any ideas how this could be fixed?

 

[bibilit]

Those 800k drives have just two switches, the left for disk protection, the right one for disk detection.

Pushing the right switch down should spin the drive.

 

[Crutch]

Pushing the right switch down should spin the drive.

It should indeed - but it does not. The drive is recognizing a disk is there - it’s clearly telling he Mac it’s got a disk it can’t read (which it can’t read because it’s not spinning...) because after a moment I get a flashing “X” icon and the disk ejects. But there isn’t even the slightest hint of a spin or indeed any mechanical movement whatsoever until the eject mechanism activates. 

 

[bibilit]

Stuck maybe

 

[Crutch]

Bumpity bump. Anyone have any ideas how to fix TWO 800k drive mechanisms that won’t spin?  They aren’t “stuck” ... meaning I can freely rotate the rotor thing with my finger.  They detect a disk, refuse to spin, then identify the disk as unreadable (and so eject it if during boot ... or ask to initialize it if the Mac is already running ... eject works perfectly well by the way, the issue really seems isolated to refusing to spin).

To reiterate:  a drive mechanism that came inside an external Apple 3.5 drive was doing this, so I swapped out the drive mechanism with a known good drive, and now they BOTH are doing it.  So strange.  Both motor circuits fried somehow by an Apple 3.5 drive controller board issue?  Anyone have a schematic for these 800k drive mechanisms?

 

[LaPorta]

What is the common factor here between the two? Was the same cable used? Or the same machine/housing? The other one still doing it when returned to it's original place?

 

[Crutch]

Thanks for asking.  The common factors are the cable (Mac externally floppy port-to-Apple 3.5 Drive) and 3.5 Drive main board.

Specifically, inside the 3.5 drive is a “Little Board” that connects to the external cable and has an internal floppy ribbon connector on it.  When I received the 3.5 Drive it wouldn’t spin, so I opened it up and connected a known-good 800k drive mechanism to the internal floppy ribbon connector inside the 3.5 Drive (meaning, still using the same external cable and Little Board).  Doing so seems to have ruined the previously known-good 800k drive mechanism, since it now acts the same as the one that came with the drive (not spinning), even when removed from the drive and put back inside a known-good Mac Plus.

It would be helpful to have a schematic for the Little Board, I suppose.  But this all seems very strange to me.

 

[Crutch]

Thanks to a link posted in BMOW’s blog years ago, I found the schematics for the “Little Board” which I guess is actually called the Daisy Chain board because it allows one (I believe only if using the 3.5 Drive with an Apple IIgs?) to connect a second drive in series.

http://bitsavers.trailing-edge.com/pdf/apple/disk/sony/Apple_3.5_Drive_Schematic.pdf

Maybe something is shorted out that damaged the electronics in the floppy mechanisms.  I will try to find out.

 

[grone]

Thanks to a link posted in BMOW’s blog years ago, I found the schematics for the “Little Board” which I guess is actually called the Daisy Chain board because it allows one (I believe only if using the 3.5 Drive with an Apple IIgs?) to connect a second drive in series.

http://bitsavers.trailing-edge.com/pdf/apple/disk/sony/Apple_3.5_Drive_Schematic.pdf

Maybe something is shorted out that damaged the electronics in the floppy mechanisms. I will try to find out.

Did you get the drives working in the end?

 

[Crutch]

Sadly no. Eventually I gave up and sold them for parts.