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Apple //c [Alps] floppy drive not working

mg.man

Well-known member
I'm working on a //c which seems fine apart from the floppy - which spins, "jiggles" the head, but does not seek to Track 0. The //c will boot from a FloppyEMU in 5.25" mode when directly connected to the internal floppy connector.

Does anyone have any experience repairing one of these - or a link to a service manual? Alps Model FDD2111-A7.
 

mg.man

Well-known member
Yep, head and rails cleaned - the latter lightly lubed. I haven't verified the speed since it locks up the //c, so I can't load any diagnostic. I can try a light bulb, but I'm pretty sure it's supposed to move the head to Track 0 (like the Disk II) when initialized - which it doesn't do. As I said, it does appear to "talk" to the stepper motor - the head can be moved back and forth freely along the rails - but no matter where it is, all it does is "twitch" on power-up.
 

bibilit

Well-known member
Probably one of the Logic chips on the board.
Not easy to tell without a little troubleshooting
 

mg.man

Well-known member
Yeah... there are quite a few test points, but all the ICs are soldered-in. :rolleyes:
I might have a chance if I could find a Service Manual... but so far, I've had ZERO luck with that!! :mad:
 

mg.man

Well-known member
Thanks, but, unfortunately, the Alps drive is a VERY different animal to the Disk II... lot's more "stuff" on the circuit board, not to mention all soldered-on ICs... 😞
 

mg.man

Well-known member
*Update* - it's working!!

After managing to track down the schematics, and swapping the 74LS125 with no change in behaviour, I decided to drag out my Apple //e and try the //c drive on that. To my surprise, it worked just fine. 😑 So... prompted by mention about voltages from someone on Applefritter, I decided to check them. Long story short, the external power "brick" was past its prime and unable to push enough current in to feed the floppy. So I put together a replacement and everything sprang to life.

I hadn't considered voltages since everything worked just fine with the FloppyEMU plugged in as a replacement... That said, the EMU is solid-state, so not nearly as current hungry... 🤔
 
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