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5.25" FDD 360 kB - reading ok, problems writing and formatting

3pcedev

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Jun 8, 2014
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730
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Australia
That's an excessive amount of work for a process that sometimes needs to be performed several times a week. :) Yes, I have thousands of old floppies and the constant use of them requires continuous maintenance on the drives I use them in. I guess for the casual hobbyist disassembly is not a problem but I just can't afford all that time and labor over and over again.

I've been using the cleaning disks for over 25 years without any problems and don't know that I would have been able to remain focused if I needed to disassemble, clean, reassemble and check these drives on a regular basis. I don't think I would have time to do the work I had at hand if it were not for the time-saving efficiency of these cleaning disks.

If you need to clean your drive that often you be running disks through it almost 24hrs a day :p

As a casual user of 5.25" disks I only need to clean my drives once a year (if that) so it's no big deal for me. I also have a strict rule that if the disk is at all flaky or dirty it goes in the bin; no exceptions.
 

DDS

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Sep 5, 2013
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I'm going to throw something into the discussion in case someone finds it useful down the road.

Before I retired I spent 42 years with a "large public futility" working on several generations of telephone switching gear. A good part of that time was spent clearing troubles caused by contamination of relay contacts and magnetic media read/write heads. In general we used some kind of solvent to (hopefully) loosen up the contamination and then some kind of media to wick up and perhaps scrub off whatever the solvent had loosened up. And that's essentially what you're doing with a cleaning disk or a Q-tip.

On newer read/write heads the assumption is that the contamination is (probably) either iron oxide or chromium dioxide magnetic media plus some of the binder that formerly held that media in place. Isopropyl alcohol is pretty good at that. But what if, as often happens with equipment that's been sitting idle for a while, the contamination is something else? If the usual techniques don't work try something else!

When I first hired on we commonly used something called trichlorotrifluoroethane as the default solvent. It was so common that it's nickname was "Instant Switchman". Switchman was the title for people who worked on telephone switches. It eventually became near impossible to get because it was found to be an "inhalation intoxicant" but years later you would sometimes still find a can hidden away by someone for those really really hard to clean problems. This stuff really really worked!

When I left we were using something called MS-730 Contact Re-Nu for relays and MS-200 Media Head Cleaner for tape and disk drive heads. All of these were in spray cans which often blasted any loosened contaminants away. But when that wouldn't work we sometimes used "bond paper" which we got already cut into strips maybe 3/8" wide by 2" long. This was used to scrub and lift contaminants much like the media in a cleaning disk.

So, anyway! If your next option is to throw the drive in the trash, maybe try a different solvent and/or different cleaning media first. Just use some sense and pick something that's safe for people and plastics.

And then again: "There are very few problems that cannot be solved with the proper application of high explosives" -- Scott Adams, author of "Dilbert" and former Pacific Bell Telephone engineer.

;-) JK about the high explosives. Don't try that at home.
 

Chuck(G)

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Jan 11, 2007
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Pacific Northwest, USA
I use cleaning disks with no problem, but then I don't scrub the dickens out of the heads. Isopropanol doesn't always do the job, though. Freon-TF is the best, IMOHO, but that's near unobtainium today. A second best is Perc, which does the job so long as you're careful.

Another option would be to use a strip of non-woven, sew-in, heavy weight interfacing fabric. Apply cleaning fluid to the end, stick it in the slot, close the drive door and gently pull it out. I've tried it a few times and it does seem to work.
 

giobbi

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Dec 23, 2012
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São Paulo country, Brazil
And then again: "There are very few problems that cannot be solved with the proper application of high explosives" -- Scott Adams, author of "Dilbert" and former Pacific Bell Telephone engineer.

;-) JK about the high explosives. Don't try that at home.

ROTFL !!!!


However, this thread went a little OT. Before to begin to start flames ;-) , I wish to return back to the original topic...

I also wish to say that:

a) The drive head is clean;
b) I'm not using a cleaning disk but, since I'm not using brute force and ignorance, I never broke or damage an head in my life (at least since 1987...);
c) I understand that not everybody will agree with me about my technique but it always worked fine for many years, so it's ok (at least for me).

and, last but not least

d) the head #1 doesn't work. I suppose it could be a problem related with the electronics. Is there any test I can do (i.e. measuring the heads voltage, signals, etc. with a probe, a scope, a multimeter, etc.) while it's trying to access the head #1?
 

giobbi

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Dec 23, 2012
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São Paulo country, Brazil
I did a simple check using a probe:

There are two connectors for the flat cables from the heads, PJ4 (head #0) and PJ5 (head #1). Every connector has 5 pins.

Using a probe, I can see that:

Idle drive:
JP4: 5=Low, 1..4 = High
JP5: 1..5=Low

Formatting:
JP4: 5=Low, 1..4 = High/Pulse
JP5: 5=Low, 1..4 = High, pulse/low while testing head 1, then low while formatting single side.

What do you think? Shouldn't both heads have the same behavior?

--Giovi
 
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