[Coco] Cleaning Coco disks (gene heskett)

[gene heskett]

On Saturday, January 21, 2012 11:53:43 PM Andrew did opine:

> Gene (or anyone else),
> 
> Would you know of any tutorials or anything on how to clean and adjust
> 5.25" drives in general (and CoCo drives in particular)?
 
I haven't googled to see if anything that old still exists on the net, but 
its worth a try.  All one can do is strike out.

> I haven't been successful at finding any cleaning disks (long out of
> manufacture, I imagine - though I remember reading back in the day that
> they weren't really recommended?).

No, they were way too abrasive IMNSHO.  I used one at the tv station till I 
wiped out the heads on an amiga drive, which after I took it apart to get a 
good look at the heads, and it had scratches in the ceramic shoe that 
carries the actual magnetics that under a medium power magnifying glass, 
looked like I'd taken a 14" mill bastard file to clean them.  From then on 
it was only alcohol (paint thinner type from Ace Hdwe) and q-tips.  And for 
q-tips I am partial to the Sherwood Medical brand that you can usually get 
at the pharmacy, a 1000 count carton, 10 paper bags of 100, is in the $10 
bill range.  Single ended, on a 6" wooden stick, many times handier that 
those little 2" plastic sticked dbl-ended stuff in the blue blister pack 
that costs just as much, and the wooden stick doesn't get eaten if you need 
to get serious & switch from alky to acetone.

> Is it possible to adjust drives without needing more than the drive and
> maybe a known-good floppy? I own a couple of dual-trace scopes if that
> would help...

I've threatened to make a test jig I could clip onto the drive connector so 
I could start and stop the motor and step it in and out, but life kept 
getting in the way so it was never done back in the 80's when it was 
needed.  Ideally it should also include a slow, about 1 second counter that 
always sends like 31 pulses out, but only 30 in, so that it will be banged 
against the Trk0 detector.  The auto step one way or the other won't muck 
the scope trace observations all that much, particularly if your sweep is 
triggered by the index pulse, but it will serve to keep the drive from 
sitting on the same track for long periods of time, both wearing out the 
track, and causing multipass erasure so that eventually your good disk is 
destroyed magnetically.  Head magnetization state is generally not a factor 
in the real world.

As for the scope, if you own it, I expect you also know how to run it. :)

As for a known good drive calibration floppy, Dyson sold those all through 
the 70-80's, had all sorts of test signals depending on what track, because 
each track was recorded in a different, vary carefully calibrated drive 
that was then diddled to have one specific error.  Because of that, the 
last new one I saw was probably 25 years ago, and about $75 in 1982 money, 
and while you could copy it, the copy was worthless.

Like most, I made do with someones distribution disk that became my local 
standard & was marked up as such with a magic marker.  Those don't of 
course have specific errors, but really,  the Trk0 setting is probably the 
most important of the bunch.  Get that right, and the drive hasn't 
otherwise been physically damaged, and you're pretty well home free till 
the heads give up.  Or in the case of a belt drive spindle, till the belt 
slippage makes you start hunting for a better one.

Re belts:  I had a cdrom refuse to open and close its drawer a couple of 
years ago, and when I took it out, the square belt on that teeny little 
motor that ran the drawer in and out had relaxed till it had no more 
tension.  So I rolled it off, cut about 3/32" out of it and superglue'd the 
freshly cut ends back together.  2 years and change later, it is still 
working fine.  Trying to butt glue one of those flat belts after taking out 
perhaps an eighth inch might be a chore, but if its the only thing you 
have, I think the phrase is to "McGiver it".  :) 

> I have a few of these older drives in my collection, and I just want to
> make them last as long as possible...
> 
I hear that, so am I, but I am beginning to get low on the 5.25's. :(  That 
means I do the lions share of my cocoing on 1 or the other of the 2 1Gb 
scsi drives I have.  With drivewire working, and a serial link on /t2, I 
have pretty good com with the coco3 from here.

> Thank you,

NP Andrew, but I likely wasn't that much help either.  Sorry.

Cheers, Gene
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