[Coco] FD-502 controller problem

Phill Harvey-Smith afra at aurigae.demon.co.uk
Fri May 19 08:44:26 EDT 2006

Quoting Charlie <chazbeenhad at hotmail.com>:

> Hello CoCo fans!
> I have a FD-502 disk controller that is giving me a bit of trouble.  A DSKINI
> on drive 0 gives an IO error
> when the "clicking" sound from the drive steps up to a faster rate. (I hope
> I explained that right.) DSKINI on
> drive 1 works just fine.

Sounds like it could be a drive/cable problem to me, have you tried  
swapping drive 0 and 1 to see if the problem moves ? if it does I  
would suspect the drive rather than controler You might want to try my  
sugestions below before doing this......

>                         Otherwise the controller seems to work fine for
> loading games and apps.

Have you tried writing to a disk in the failing drive ? note if you  
are going to try this use a disk you don't mind losing incase it gets  
trashed. It sort of sounds like drive 0 has a problem with it's write  
enable from the symptoms you have described, as write track (format)  
would use this, in the first pass over the disk.

Something else you can try, format a disk in drive 1 and save some  
files on it, then try formatting in drive 0, I suspect that after the  
error you will still find the files on the disk are ok, as nothing has  
been writen, then again this might verify ok (the second pass where  
the step speed increses), as it has valid tracks written by drive 1 :).

> I opened the controller and cleaned all the contacts. I can see that some of
> the contacts have the tin worn off and
> are looking the color of copper and not silver. Should I re-tin these with
> solder?

I would advise against this as it will make the connector thicker,  
which could damage the connector on your CoCo/multipak. An easy way to  
clean edge connectors is with a sheet of blank paper, alternatly you  
can get silicone cleaning blocks designed to clean connectors which  
also work well.

> Besides the worn contacts would anyone else know what could be wrong with
> the controller?

See above comments :)



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