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Old 1st Nov 2021, 4:04 pm   #1
drykid_
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Location: Hereford, Herefordshire, UK.
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Default Canon 5.25" drive with stuck head carriage

Hi, my first post here though I have found this forum an invaluable resource in the past when researching faults I've encountered in the past with various vintage equipment...

Anyway I am trying to bring back to life a Canon 5.25" drive (from a Yamaha QX1 sequencer, although as far as I can see it's just a generic Canon design that no doubt was used in vintage computers from the era too.)

The issue with it appears to be a stuck head carriage. Not only does the carriage not move at all when opened up to watch it in operation (although the disk itself spins), but I'm unable to move it manually no matter how much force I apply to it. It seems to be absolutely jammed in place. My guess is that someone has tried to lubricate it at some stage with something that has since dried up completely. Am at a bit of a loss what to do really; short of hitting it with a hammer I can't think what else I can do to get the thing to move.

One thing I did establish is that by loosening the two screws at either end that hold the rails themselves in place I found I could manually rotate the rail on one side relative to the carriage but not the other. So it only seems to be jammed on one of the rails as far as I can see, but obviously that's more than enough to stop it moving as a whole. It's a shame actually that it's not the other rail that it can move on as the jammed one has two points of connection instead of one, which makes trying to apply force a lot more difficult than it would be if there was only one point of contact with the rail.

Any suggestions? Also can someone confirm that I should be able to move the head carriage manually on a model like this?
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Old 1st Nov 2021, 4:46 pm   #2
TonyDuell
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Default Re: Canon 5.25" drive with stuck head carriage

It looks like a taut-band mechanism, so unless the stepper motor is seized then the carriage should move freely by hand. I assume you are doing this with the drive powered down.

The problem for you is that if you dismantle the taut band system, you will lose the radial alignment of the head (what most people call 'head alignment'. And resetting that is a moderate task with a disk drive exerciser and 'catseye' disk, and almost impossible without them. You can get the drive working again, but until you set up the alignment it won't read your old disks.

You must not force things, or you might break the plastic head carriage. Spares of those are stocked alongside hen's dentures and rocking horse manure! Also you must not put any burrs on the slide rails if you grip them. In a lot of cases the slide rails were matched to the head carriage and supplied with it, you can't just swap them around.

A safe lubricant to try is one of the ptfe-based dry film ones. A few drops of that on the stuck rail near the carriage bearings might get it moving. Other than that I think you will have to take the thing apart and try to move the rail separately Then try to find somebody who has the stuff to do an alignment. I do, but I am not close to you.
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Old 1st Nov 2021, 5:07 pm   #3
drykid_
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Default Re: Canon 5.25" drive with stuck head carriage

Quote:
Originally Posted by TonyDuell View Post
It looks like a taut-band mechanism, so unless the stepper motor is seized then the carriage should move freely by hand. I assume you are doing this with the drive powered down.

The problem for you is that if you dismantle the taut band system, you will lose the radial alignment of the head (what most people call 'head alignment'. And resetting that is a moderate task with a disk drive exerciser and 'catseye' disk, and almost impossible without them. You can get the drive working again, but until you set up the alignment it won't read your old disks.

You must not force things, or you might break the plastic head carriage. Spares of those are stocked alongside hen's dentures and rocking horse manure! Also you must not put any burrs on the slide rails if you grip them. In a lot of cases the slide rails were matched to the head carriage and supplied with it, you can't just swap them around.

A safe lubricant to try is one of the ptfe-based dry film ones. A few drops of that on the stuck rail near the carriage bearings might get it moving. Other than that I think you will have to take the thing apart and try to move the rail separately Then try to find somebody who has the stuff to do an alignment. I do, but I am not close to you.
Thanks, I don't think it's the stepper motor that's seized because I can slightly turn it in either direction. So there's no reason why that movement shouldn't translate it into movement of the carriage I wouldn't have thought if the carriage itself was free to move on the rails.

With regard to the head alignment it's quite possible that I've messed that up already in my attempts to free the carriage. My thinking is that if I could at least get the carriage free then I could look into alignment as a separate task. But I haven't even got the carriage free so far.

I'm happy to try the lubricant you suggest, but to be honest it feels like at this point lubrication is pointless because it needs something that will actually break down whatever has it fixed in place currently. Possibly some kind of degreasing agent maybe? But because the carriage is mostly plastic I'd be worried about using the wrong stuff.

I'd be more than happy to send the drive to you if you were willing to look at it, although it sounds like there's nothing you could do with it unless I can manage to free the heads first.
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Old 1st Nov 2021, 6:08 pm   #4
SiriusHardware
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Default Re: Canon 5.25" drive with stuck head carriage

If Tony is willing... I would suggest that it might be better to leave the sledge seized and let him sort that out, as he obviously has the right potions for the job.
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