[Coco] Disk controller

[Gene Heskett]

On Tuesday 15 April 2014 20:20:58 Chad H did opine:

> Well, not sure if those controllers have 7416 buffer chips or not, but
> one of my FD-502 controllers was acting erratic and after desoldering
> the 7416's and replacing them with beefier 7406 buffer chips it was
> good as new.  I went ahead and did the upgrade to my other controller
> to. Have never since had any further problems out of either one.  This
> might be something to check IF it has the 7416 chips..
> 
> http://www.mediafire.com/view/cde2vmcqp63jt/Board%20Images#4sqrj7b4u1qpp
> 5q
> 
> 
> 
> -----Original Message-----
> From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com]
> On Behalf Of Bill Pierce Sent: Thursday, March 27, 2014 10:17 AM
> To: coco at maltedmedia.com
> Subject: Re: [Coco] Disk controller
> 
> 
> Gene, that was going to be my reply :-P
> I spent about 3 days one time trying to figure out why my drive wasn't
> working. I had moved my system from one room to another and went from a
> working system to a drive coming on and nothing else happening. I don't
> remember why I tried flipping the cable, but that what I ended up
> doing. When that solved te problem, I then marked the top side of the
> cable on both ends to make sure that didn't happen again. As a note,
> most 3.5 drive cables can't be flipped as they have a guide pin, but on
> a Coco, the initial cable is usually terminated with the (then)
> standard 5.25 type ends. There's usually an adapter from 5.25 style to
> 3.5 style at the drive end of the cable. In my setup, it is actually
> inside the case on the adapter plate. It has a "single drive" cable
> running from the controller to the drive case. The cable then plugs
> into a "card edge" on the back of the drive case (3rd party, not Tandy)
> with 5.25 style connection, then continues via ribbon cable inside with
> 2x 5.25 style connectors to the adapter plate which also has a 5.25
> card edge built in that goes to a very short 3.5 style cable that
> connects to the drive. Talk about a hassle to clean all the card edges,
> 4 in all from the Coco to the drive. 5 if I use a second 3.5 drive.
> 
> I also have several "hybrid" cables that have 5.25 style connectors as
> well as 3.5 style. All my 3.5 drives have drive select jumpers so I can
> use them in any order I want.
> 
> 
> Bill Pierce

However, ONLY the last drive in the chain is to have the terminating 
resistor packs installed, or, in the case of the 3.5's, one might have to 
get a glass and read the artwork on the pcb to find the cut or bridge 
jumper that controls that.  And in my dumpster diving I have yet to find a 
3.5" drive that was switch selectable.  Occasionally one might be 
selectable via solder blob bridges, so you are lucky in that regard.  What 
make & model are yours, so I can be on the lookout?

Cheers, Gene
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