[Coco] Issues with 26-3022 interface

[Gene Heskett]

On Tuesday 12 February 2013 00:16:11 Daniel Campos did opine:

> Hi Gene,
> 
> Em 12/02/2013 02:19, Gene Heskett escreveu:
> > On Monday 11 February 2013 22:40:50 Daniel Campos did opine:
> >> Hello,
> > 
> > What jumper is set for that drives address?  Where you have it, on
> > that "PC" cable, it should be set with ds1 jumpered, and you should
> > have had to type DSKINI1.
> 
> Since the beginning, I used a PC cable but have removed the twist of the
> cable. It's a straight thru cable now.
> 
> > The end of that cable is twisted, so that the drive plugged into the
> > end of the cable is also set as drive 1.  But the cable twist makes
> > it drive 0.
> > 
> > For coco drives, I generally reset the address jumpers so the drives
> > are addressed in sequence, starting with drive0=ds0 jumpered, and
> > replace the cable with a straight thru cable, replacing any plugs on
> > the cable that have missing teeth in the sockets.
> > 
> > So your use of DSKINI0, means that drive is properly jumpered I
> > believe.
> 
> Yes. That was the first drive from the TRS-80 so it was already jumpered
> to DS0.
> 
> > The next thing is that there needs to be terminations, in the last
> > drive on the end of the cable /only/, and you will have all sorts of
> > I/O errors if there are none.  They /must/ be on the end of the cable
> > too else the cables signals will have edge ringing from the
> > unterminated stub I see sticking out.  So if that drive has 1 or more
> > empty minidip sockets adjacent to the edge connector, you are missing
> > those terminations.  The best source for those is probably another
> > old drive.
> 
> Yes, there is a DIP socket but I don't know his function. Both drives on
> the TRS-80 don't have any terminations on this sockets. Bellow goes a
> picture.
> 
> http://img248.imageshack.us/img248/5832/img1265u.jpg

Yes, I'd say that is what its for.  Also, the green jumper to its left is 
probably the addressing jumper.
> 
> > Specifically, what is the model number of that drive?  So-called 1.2
> > meg PC drives turn at 360 rpms, but the coco controllers are all
> > timed for 300 rpm drives. I just listened to the DSKINI again, and
> > its too slow, indicating it may be a 360 rpm drive and is therefore
> > missing every other index pulse.
> 
> That one is a drive from Prologica. Model D505/2. Even here I couldn't
> find a service manual of this model.
 
That doesn't mean a lot to me, and it not a direct hit on google.  The 
drive should have a makers label, either on the back, out of sight in that 
picture, or possibly on one of the side faces.

> > I also noticed on the 2nd playback that the head assembly is /not/
> > moving, which it should be a small amount inward with every click you
> > can hear, then sweep back out as it starts the verify run.  Can you
> > move it by hand when the power is off?
> 
> yes, the head doesn't move. I can move it with my hand and the drive
> works fine on the TRS-80.

What model TRS-80?
 
> > At its age, the grease on the heads slide rails could have turned into
> > glue, so you'll likely have to grab a can of denatured alcohol, and a
> > carton of cotton swabs on sticks, getting it brand new clean and then
> > giving the rods a coat of light oil, similar to sewing machine oil. 
> > Move the head in and out to get access to the whole guide rod length.
> > 
> > If you have a product called 3in1 oil, thats quite usable.  The spray
> > lubes aren't.  They get all over places they shouldn't, and they dry
> > to a wax, not an oil film.  Works great for a day, maybe 2, & then
> > stuck again.
> > 
> > And what happens if you push it toward the middle of the disk, power
> > it up, and do a dir0?  It should sweep the head back to the outer,
> > track 0 position, and hammer the stop for a second or so since the
> > coco ignores the drives track0 sensor, then step to the middle of the
> > disk to read the directory on track 17.
> 
> It only moves by itself if I grab the head for the outer edge and make a
> DSKINI, so it starts moving towards the center of the disk, when it
> reachs the center it gives me an IO ERROR.

Does it try to back out just before the IO ERROR, or just make the noise?

> For what I could understand, the drive head is not being moved at all.
> It only moves to the center if I manually have it positioned before
> doing the DSKINI.

This cable or controller failure from the sounds of that.
 
> > If it doesn't do as described, start by ditching that cable in favor
> > of a straight thru, all teeth present in all 3 connectors version.  I
> > am thinking the control signals from the coco are getting scrambled
> > by that 'PC' cable.
> 
> I have removed that loose end of the cable, but no results so far. And
> the connectors have all teeth.

Now we do have a puzzle.  Do you have access to another coco disk 
controller?  Or do you know someone with an oscilloscope so that the step 
and dir signals can be inspected?  And of course the manual for the 
controller so the pins that carry the signals can be identified?
 
> > Please advise the list what you found when you did the exercises
> > above.
> > 
> > Cheers, Gene
> 
> Thanks!
> Daniel
> 
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Cheers, Gene
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