Sony 800k Floppy Drive oddities

[Ken Newman]

Anyone know about Sony 800k floppy drives?
I've been learning a lot about them lately as I attempt to get a couple of MacPlus computers ready to sell. I watched a few YouTube videos (especially those from @JDW, which are pretty amazing!), and learned a LOT about what I need to do with these drives to get them working again.
I thought I had it all figured out, what with disassembling the drives and lubricating them, replacing that one gear in the eject mechanism and so forth. But a few of the drives just simply would not read. That is, the head assembly stayed at the zero point even with a disk inserted. So I thought they were all bad. I should probably point out that I was connecting them to the connector on the logic board with a drive cable with a yellow stripe, because I heard that the cable with the red stripe was only for older (128k?) computers with different drives or something.
But then yesterday I thought I'd try connecting the drives to the external port, and amazingly enough, they worked! So then I tried connecting one of the questionable drives with an (internal) drive cable with a RED stripe, and amazingly enough, it worked!! Connected one of the drives that I had previously considered "good" to the cable with the red stripe, and it constantly ejects, as I had heard it would with the red stripe cable.
So my question is, what's with these drives that work perfectly with the red stripe cable or externally, but they DON'T work with the internal yellow stripe cable??
Please watch the attached video to see these differences.
Many thanks to anyone that can help me with more info!


View attachment FloppyDriveDifferences.mov

 

[Ken Newman]

I've just been made aware of a very interesting web page: https://www.retrotechnology.com/herbs_stuff/m_parts.html#800K that details some of the differences that I've been noticing. Apparently some of my drives have black text on their labels while others have red text on their labels, and this makes a big difference!
Now, if I can just get it all sorted out so that all drives work all the time, that will be wonderful!

 

[bibilit]

Interesting reading. 

Had more or less the same experience a couple of years ago, while testing some drives like you did. 

Using an external cable didn’t worked for me and the drive was ejecting the floppy or the drive was sort of crazy. 

On the other hand when connected to the proper inner cable the drive was working fine. 

I learned that connecting directly the cable to the floppy wasn’t the way to go, as the cable is first connected to a small board, then a small ribbon cable is hooked to the drive. 

So  some circuitry should be in between. 

 

[pinto_guy]

For what it's worth, here is a recent post that I contributed on this issue. I do not offer an explanation, but simply an observation of different bahavior with respect to this problem with 800k FDDs