Atari 1050 diskette drive repair

[Ralph E. Dodd]

> Date: Thu, 22 May 2008 07:56:27 -0400 (EDT)
> From: Steven Hirsch <snhirsch at gmail.com>
> Subject: Atari 1050 diskette drive repair
> To: Classic Computers Mailing List <cctech at classiccmp.org>
> Message-ID: <alpine.DEB.1.00.0805220747180.6891 at duo>
> Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII
>
> 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.
> It looks like the head-step pulses are generated in software by the
> onboard 6507 CPU.  The four phases appear on PB2-5 of a 6532 IO interface
> and are presumably getting cycled in the correct sequence since the head
> moves quite smoothly until it hits the physical stop.
> I've already verified supply voltages and inspected the board closely for
> burn marks, broken traces, etc. and reseated all the socketed ICs.
> The unit is fitted with the 'US Doubler' enhancement, about which I know
> very little.
> Would appreciate any tips on troubleshooting.
>
> Steve
Steve,

The only problem that I've had with 1050's is that the felt pressure pad 
that replaces the top head will fall off.  I don't remember the exact 
symptoms because it's been a few years.  Take a look, it couldn't hurt.

Ralph