diagnosing dead Mac 128K floppy drives

[schuetz1619]

Is there any user-doable diagnosis for Mac 128K floppy drives? When I turn on the machine I get the expected flashing question mark. I then insert a system disk (newly written, non-defective 400K single-sided disk, system 1.01), but the disk does not click into place, nor does the drive start to turn. This is true both of the internal disk and an external disk. I get the same result (actually, lack of result) with any disk I insert, including the original system disk.

I have replaced the clock battery and verified that it is providing 4.5 v.

The front side of the programmer's switch button causes a restart to the flashing question mark; the back side of the switch instantly yields a Sad Mac, code "0F000D".

I'd sure like to do whatever I can by way of diagnosis before taking the unit to a repair shop.

Many thanks,

schuetz1619

 

[David Schmidt]

Is there any user-doable diagnosis for Mac 128K floppy drives?

So, the disk doesn't drop into either drive? Hmmm. Both could be bad, but that seems kind of unlikely. Any chance there's a disk already in either or both? (They should auto-eject if so, but...) Anything interesting when you stuff a (large) straightened paperclip in the hole?

Are you certain the external drive is a 400k one? You can identify it with help of this page:
http://www.vintagemacworld.com/drives.html

Starting by dissembling and cleaning the external drive will be easier than pulling apart the Mac 128...

 

[MacTech68]

The 400K drives do commonly suffer from hardening lubricating grease. Sliding surfaces also get caked up with dust.

Stripping the eject mechanism, cleaning it and re-greasing it will usually solve the problem if that is ALL that's wrong with it.



EDIT: here is a good starting point.
http://lisafaq.sunder.net/lisafaq-hw-floppy_lube.html
Yes, it's for a Lisa drive but they are essentially the same mechanically.