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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 30th Mar 2014, 10:35 am   #1
'LIVEWIRE?'
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Question Replacing the Capstan 'sleeve' in a Sharp GF6060

This machine has (had!!) a rubber 'sleeve' in the capstan bearing, through which the capstan shaft passed, and which drove an idler wheel in Play & Record Modes. The sleeve has softened and almost turned to sticky 'goo'
Any suggestions as to with what it might be replaced? The main considerations are that it must fit into the capstan housing between the upper & lower bearings, and be of a suitable diameter to engage the idler wheel. The hole diameter is also critical since the capstan shaft must be a tight fit so that the sleeve revolves with the capstan. Is this a tall order??
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Old 30th Mar 2014, 11:06 am   #2
Lloyd 1985
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Default Re: Replacing the Capstan 'sleeve' in a Sharp GF6060

Would several layers of different sized heat-shrink do it?

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Old 30th Mar 2014, 11:11 am   #3
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Default Re: Replacing the Capstan 'sleeve' in a Sharp GF6060

This is a common fault. Aiwa HiFi separates decks were similarly afflicted.

I've used a bit of sleeving pulled off some screened cable, others have had success with snippets of fuel hose from model shops.

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Old 31st Mar 2014, 9:04 pm   #4
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Default Re: Replacing the Capstan 'sleeve' in a Sharp GF6060

I use silicon RC fuel line for this, it's perfect and the best bit is that because it's slightly harder than the original nitrile, you can use O rings for future idler tyre replacements. Most recently, I've restored several GF-555s to full working order and have used the stuff in these as shown in the attached image of the decks from my own example, owned since new and only requiring the job for the first time last ytear.

The kind to order is 5mm o/d by 0.98mm i/d and I have a roll in so if you get stuck, just ask, I wouldn't be looking for anything for the piece you'd need to fill the space between the Oillite bushes in the capstan window on that machine; around 8mm if this has the same transport as the 9090, 9191 and 9494.

Sharp must have changed the design of the deck in the 6060 at around the time they brought in the waffle grilles to replace the earlier, round ones as I've worked at 6060s whose capstans ran against the idler tyre directly and no, they hadn't had the sleeves removed as doing that causes the tyre to catch on the edges of its window and seize the whole thing.
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Old 1st Apr 2014, 9:29 am   #5
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Default Re: Replacing the Capstan 'sleeve' in a Sharp GF6060

Thanks, John & Nick. I'll see if I can get some silicon fuel line. Don't have anything similar to hand, AFAIK
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Old 3rd Apr 2014, 2:55 pm   #6
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Default Re: Replacing the Capstan 'sleeve' in a Sharp GF6060

I did just this a couple of years ago. There's a thread on it.

https://www.vintage-radio.net/forum/...ad.php?t=27270

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Old 9th Apr 2014, 9:01 am   #7
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Default Re: Replacing the Capstan 'sleeve' in a Sharp GF6060

Presumably the original sleeve was fitted on the capstan shaft, with the flywheel/capstan & bearing bush in situ in the mechanism, but before the top bearing was inserted, but to replace the sleeve, I shall put a suitable length of tubing inside the bearing assembly, then push the flywheel/capstan up through from below, as I can't see any other way to do it.
Because of this I don't see how heat shrink sleeving can be used, since it would have to be shrunk in place after the capstan is refitted.
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Old 10th Apr 2014, 11:25 pm   #8
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Default Re: Replacing the Capstan 'sleeve' in a Sharp GF6060

Spot on, to fit the silicon sleeves I've always done it by pulling back the flywheel to withdraw the capstan, putting a suitable length of the tube into the space between the Oillite bushes, then pushing the flywheel back into position to get the tube over the capstan. Using the 0.98mm I/D stuff that you can just about see in my image, the important thing is to avoid moving it too much once [the tube] is in position and the capstan reentered. If it's in contact with the face of the outer bush when the capstan has been entered, then use something like the blade of a small craft knife to push the sleeve back toward the inner bush so that it isn't touching at either end of the bearing block.

Recently, as I was explaining to an old friend of mine how she could do the same to her own, much loved but lacking takeup GF-9494 which I'd sold to her around 20 years ago (she's a vet, so has suitable transferable skills), she suggested that catheter tube might be even better as it has a slightly rough surface and is a little stiffer. Before writing this post, I gave her a call to ask whither she'd tackled the job yet and she has, using catheter tube along with a new idler tyre of the original, square section. She reports that the transport is stable and fully functional, the same fitting technique applies IE; cut a piece of tube very slightly shorter than the distance between the bushes, push capstan through, craft knife, etc.

It would of course be possible to fit the sleeve by removing the outer bush and replacing that after sliding the tube along the capstan, but once the block is in place, getting access to press squarely and with sufficient force to enter the bush fully into the block is tricky so I'd tend not to put myself through the extra hassle.
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Old 13th Apr 2014, 6:34 pm   #9
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Default Re: Replacing the Capstan 'sleeve' in a Sharp GF6060

I have now found a length of the right diameter sleeving, cut a piece about 0.3" long, and fitted it. After test running the recorder on and off for about an hour it 's working fine, although I'll give it a longer test to be sure that continues to work correctly. The inner diameter of the sleeving was such that the capstan shaft was a very tight push fit through it, so it shouldn't slip on the spindle (famous last words!), so, as long as thereis sufficient friction between the outer surface and the idler tyre it drives, it should be a case of 'problem solved!
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