[Coco] Help with my CoCo FDD

[Gene Heskett]

On Wednesday 21 November 2018 01:08:24 Walter Zambotti wrote:

> Thanks guys.
>
> I have tried the cable both ways now and I definitely had it the
> correct way.
>
> Plugging it in the other way causes the led to light and the motor to
> spin even with the controller is disconnected from the CoCo.
>
> I re-clamped both cables but no difference.
>
> Re-cleaned all contacts with newspaper and blew out all the
> connectors.
>
> Jumpers settings tried:
>
> None - nothing starts
 (correct)
> D0 - only dskini0 starts
( which is wrong, mx missing)
> D1 - only dskini1 starts
(ditto)
> D0 & D1 - both dskini0 & dskini1 start
(wrong, both drives will attempt to put read data on the data line)
> MX both start
(runs motors, but without a Dn, no data to data line)
> D0 + MX : both start
(correct, only one drive, D0, will rx/tx data)
> D1 + MX : both start
(also correct, but data will rx/tx from D1)

> All the above combinations + Term : No change to above
>
> When I say start the motor comes on and the head returns to zero and
> then performs 34 steps and then returns to zero before getting an I/O
> err.

(classic case of dirty/worn out head. assuming the command was a 
dskini0/1)
>
> Also driveX + dir causes the FD to seek forwards and backwards 3 or 4
> times before failing.
again, dirty head/worn out heads/bad disk)
>
> So I thinks it's formatting but fails when trying to read.
Paint store alcohol, wet long q-tip, Sherwood from drug store, gently 
head heads. Give time to dry before re-inserting disk, minute or so or 
use a clean dry q-tip.

If clamping rossette is collapsed from old age, maybe the disk itself is 
not spinning in the case of a 5.25 disk, but 3.5's are keyed and will 
spin anyway if motor turns.

> I'm stumped!
>
> I have determined that one of the chinon drives is faulty as the
> stepping motor refuses to move the head towards track 0.

The rods the head carriage slides on need cleaned and re-oiled, light but 
non-drying oil, 3-n-1 or sewing machine, possibly the driveing screw is 
caked full of hardened 30 year old grease, clean until the screws spiral 
groove is shiny clear to the bottom of the groove and relube, chassis 
grease suggested, or vaseline maybe. Check the wire that is the groove 
follower for noticeable wear. I've seen then worn plumb off in Amiga's.

> Short of scoping pins for signal output I'm not sure what to do.

Thats the next step after the clean and lube. And it sounds like the data 
pin is what you need to scope. For a dskini you should see data from the 
controller while its stepping in, and when it steps back out to do the 
verify phase, you should see data from the drive, and it sounds as if 
the drive isn't returning usable data if that where you are getting the 
io error.

There is also a possibility the controllers 1773 is blown. At the tv 
station, with a 255 foot pyrod tower for a lightning rod 30 feet out the  
back door with a 4" wide copper ground strap interconnecting the tower 
to house ground, our stuff took a beating when mother nature got upset 
because somebody called that stuff butter. And the coco's do not have 
grounded power cords. I lost 1773's in the smaller, later controllers 
several times. That chip is IIRC an NMOS tech chip, and they can grow a 
purple plague that kills them just from old age and average humidity 
alone. In that case, see if you can find a Fujitsu MB-8877 as its a CMOS 
tech chip and not subject to that particular failure. And I think its a 
drop in for a WD-1793 in the 40 pin pkg. All are going to be very old 
stock and hard to find.  Check the graveyard electronics site as a last 
resort.
> Can anyone recommend a replacement FD and controller! It needs to
> support 42 tracks!!!

Ouch.
>
> Walter
>
> -----Original Message-----
> From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of EDDY
> SZCZERBINSKI Sent: Wednesday, 21 November 2018 7:06 AM
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Subject: Re: [Coco] Help with my CoCo FDD
>
> I may be wrong in some instances but usually, cable goes "down" when
> connected. I always try that first when I don't know the direction and
> it always worked so far with lots of equipments. Hope it helps
> Eddy
>
> ________________________________
> De : Coco <coco-bounces at maltedmedia.com> de la part de Walter Zambotti
> <zambotti at iinet.net.au> Envoyé : mardi 20 novembre 2018 01:46 À :
> 'CoCoList for Color Computer Enthusiasts' Objet : Re: [Coco] Help with
> my CoCo FDD
>
> >Are there any "dividers" in the cable plugs to keep you from plugging
> >them in backwards? In non-factory stuff thats often left out,
> > allowing the cable to be plugged into the controller or the drive,
> > upside down. That divider/blocking thing is close to the pin 1 end
> > of the connector, so locate the connectors pin one, often marked by
> > a triangle and place the cable so pin one is near the slot in the
> > pcb tongue of the drive that the divider, if present slides into. 
> > On both ends of the cable. If the access led is still on, then
> > you've likely blown a 7404 in the controller, it does happen very
> > occasionally.
>
> No dividers but they are clearly numbered 1-2 to 33-34
>
> The number 1 is also adjacent the red wire on the ribbon cable.
>
> I have been placing pin 1 on cable to pin 1 on FD connector (this is
> the pin close to the connector divider/groove)
>
> However the connector on the controller is not so clearly labelled. 
> There is a "1" printed on the board very close to one end of the
> connector.  Could mean something else!!!
>
> I will try flipping the connector and blowing out the connector.
>
> I have to get home first!
>
> Walter
>
>
>
> -----Original Message-----
> From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Gene
> Heskett Sent: Tuesday, 20 November 2018 10:22 AM
> To: coco at maltedmedia.com
> Subject: Re: [Coco] Help with my CoCo FDD
>
> On Monday 19 November 2018 19:35:10 Walter Zambotti wrote:
> > Thanks
> >
> > The access led always seems to be on at all times!
>
> Thats usually a good sign its plugged in upside down, effectively
> interchanging the signals and grounds. Doesn't usually do any damage,
> but could.
>
> > One of my cables has a double end like you describe. The other is
> > just single ended. Neither are tandy factory, just some 3rd party so
> > I'm not sure if either is equivalent to the factory cable.
>
> So they are both fully wired cables. which means you need to jumper
> the drive addresses as 0 and 1.
>
> Are there any "dividers" in the cable plugs to keep you from plugging
> them in backwards? In non-factory stuff thats often left out, allowing
> the cable to be plugged into the controller or the drive, upside down.
> That divider/blocking thing is close to the pin 1 end of the
> connector, so locate the connectors pin one, often marked by a
> triangle and place the cable so pin one is near the slot in the pcb
> tongue of the drive that the divider, if present slides into.  On both
> ends of the cable. If the access led is still on, then you've likely
> blown a 7404 in the controller, it does happen very occasionally.
>
> > My Tandy drive and controller came with the factory cable but I need
> > to get that out of storage.
> >
> > I don't know if my setup is common but I know that I was able to
> > access both sides of the floppy from disk basic by using drive(0/1)
> > without changing jumpers.
> >
> > OS9 could access both sides as a single floppy.
> >
> > What I didn't try was jumper D1. I assumed D0 or none.
>
> With cables with the twist, both drives are D1
>
> > At the moment the only jumper setting that seems to get close to
> > working is a single jumper in MX. Then dskini(0/1) begins working.
> >
> > I will reclamp the cables as I didn't consider this! Thanks.
> >
> > The edge connectors are clean.  A little gentle use of some steel
> > wool.
>
> Which is conductive, give it a good blowout with an air hose.  Thats
> why I said paper, as in newsprint, it has just the right abrasive
> effect, and is not conductive (unless soaked in salt water)
>
> > Walter
> >
> > -----Original Message-----
> > From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Gene
> > Heskett Sent: Monday, 19 November 2018 4:35 PM
> > To: coco at maltedmedia.com
> > Subject: Re: [Coco] Help with my CoCo FDD
> >
> > On Monday 19 November 2018 01:21:36 Walter Zambotti wrote:
> > > >This has the quack and waddle of two ducks, both wanting to be
> > > >first, drive 0.  >From prior experience the first thing I'd do is
> > > >look into the edge connector pulled >off either or both drives.
> > > > Missing teeth? then both drives need a jumper on 0 (1) >2 3 MX
> > > >Term 0 (1) 2 3 MX Term because the twist in the cable makes the
> > > >2nd >& last drive into drive 0, and in any event you'll need a
> > > >jumper on Term for last
> > > >
> > > > >drive on the end of cable.
> > >
> > > Thanks Gene
> > >
> > > I should have said I have backed off from trying to get both
> > > drives working together and all my testing was just with 1 drive
> > > at a time.
> > >
> > > So if I only have 1 drive connected then I should just need a
> > > jumper on 0 & Term!
> > >
> > > However one of the drives only spins up when I jumper MX even when
> > > it's the only drive!  I'll check the edge connector.
> >
> > With the factory cable, the end connector is drive 0, but it needs a
> > jumper set for drive 1. The twisted part of the cable makes it drive
> > 0. the drive set as drive 1 is then the middle connector and will be
> > drive 1. Stuff is numbered in base 0. Make that drive work by
> > itsself on the end of the cable, and verify that a dir(1) doesn't
> > light its access led, but does run the motor. You might have to use
> > some contact cleaner and some newspaper to clean the card edge
> > patterns on the drives, clean until the newspaper stays clean if you
> > get some fresh paper, wet with cleaner and go back again, pinching
> > the paper against both sides of the contact, particularly if it
> > looks to be solder plated. If gold, its not very thick so be more
> > gentle. At the cables age, if you can see a space in the cable to
> > connector joint, don't be afraid to stick it in a vice and clamp it
> > tight again. Its now 30+ years old and a lot can happen to an
> > insulation displacement connector with that sort of age on it. 
> > Where the internal fingers punch thru the wires  as they are pressed
> > into the slit in the contact pinching and connecting to the wire was
> > never what we'd call a gas tight joint to start with. So oxygen from
> > the air we breath does get in to oxidize things. You may find its
> > bad even after the trip to the vice, so don't be surprised if you
> > have to order up enough of those connectors and some 34 conductor
> > cable to make a newer one.
> >
> > I've had to do it 2 or 3 times now with the db25's used to drive my
> > shop cnc machinery at less than 10 years. Thats a much dirtier
> > environment though. Cutting oils and "swarf", aka the metal
> > cuttings, can get into the darnedest places. Biggest problem is the
> > keyboards, so a lot of this stuff does have a mouse or keyboard, but
> > a touch screen. But BIG touch screens cost too much, so I've
> > resigned my self to losing at least a keyboard a year somewhere in
> > the shop.
> >
> > > I'm going to get my Tandy ctrl and drive out of storage and test
> > > that.
> > >
> > > That should at least prove the CoCo is not the problem.
> > >
> > > Walter
> >
> > Good idea.
> >
> > > > -----Original Message-----
> > > > From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of
> > > > Gene Heskett Sent: Tuesday, 13 November 2018 1:11 PM
> > > > To: coco at maltedmedia.com
> > > > Subject: Re: [Coco] Help with my CoCo FDD
> > > >
> > > > On Monday 12 November 2018 23:32:03 Walter Zambotti wrote:
> > > > > Hi guys
> > > > >
> > > > >
> > > > >
> > > > > Advance help request.
> > > > >
> > > > >
> > > > >
> > > > > I was cleaning up my FDD and a jumper fell out (from I don't
> > > > > know where!) And there are numerous jumpers on the FDD and I
> > > > > don't know where to put it back.
> > > > >
> > > > >
> > > > >
> > > > > After that I can't read any of my FDs!
> > > > >
> > > > >
> > > > >
> > > > > I'm going to take a few pics of the thing and post them online
> > > > > in the hope one of you guys might be able to help!
> > > > >
> > > > >
> > > > >
> > > > > Walter
> > > >
> > > > Panasonic did at one time have that stuff on the web as .pdf's.
> > > > But that was 20 years back too. I have an earlier factory manual
> > > > on the JU-455, but its not that new so the pcb is probably
> > > > different. But set that one on your scanner glass, and send me a
> > > > PM as a multimegabyte jpeg, with the scanner running at at least
> > > > 600 dpi, so I can compare it with what I have. Send it to me,
> > > > not the list as it will be huge.
> > > >
> > > > --
> > > > Cheers, Gene Heskett
> > > > --
> > > > "There are four boxes to be used in defense of liberty:
> > > >  soap, ballot, jury, and ammo. Please use in that order."
> > > > -Ed Howdershelt (Author)
> > > > Genes Web page <http://geneslinuxbox.net:6309/gene>
> > > >
> > > > --
> > > > Coco mailing list
> > > > Coco at maltedmedia.com
> > > > https://pairlist5.pair.net/mailman/listinfo/coco
> > >
> > > --
> > > Cheers, Gene Heskett
> > > --
> > > "There are four boxes to be used in defense of liberty:
> > >  soap, ballot, jury, and ammo. Please use in that order."
> > > -Ed Howdershelt (Author)
> > > Genes Web page <http://geneslinuxbox.net:6309/gene>
> > >
> > > --
> > > Coco mailing list
> > > Coco at maltedmedia.com
> > > https://pairlist5.pair.net/mailman/listinfo/coco
> >
> > --
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > Genes Web page <http://geneslinuxbox.net:6309/gene>
> >
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > https://pairlist5.pair.net/mailman/listinfo/coco
>
> --
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Genes Web page <http://geneslinuxbox.net:6309/gene>
>
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> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco
>
>
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>
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-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>