Atari 1050 diskette drive repair

[Tony Duell]

> 
> Anyone have experience with these?  I have a defective unit (purchased on 
> eBay - sad story) that tries to bash the drive head to death against the 
> Track 0 stop when turned on.  I picked up the service manual and 
> schematics and was able to verify that the Track 0 sensor was working and 
> that that NTRACK00 (pin 34) on the 2793 FDC chip is pulled high at that 
> point.

I don;t have the data sheet in front of me (and I certainly don't haev 
the 1050 schematics here), but if that signal name 'NTRACK00' means the 
obvious thing, it's _not_ Track0. In other words it should be low when 
the head is on track0. 

If it's not, it would explain why the drive is hammering the head into 
the end stop, looking for a track 0 signal.

-tony