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Old 14th Apr 2023, 5:39 pm   #1
Malcolm G6ANZ
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Default Sharp rt 3151

I have been given one of these cassette decks to fix. The faults as found were, no rewind, and no play. Fast forward worked. The usual reason for the lack of rewind is the small drive gear breaking up. Sure enough that had happened on this example. These are not available from Sharp due to the age of the deck. But there is a chap on eBay making 3D printed ones for a very modest price. I purchased one, and two came a week or so later. They needed the centre hole drilling out to 1.5mm as they were made without a hole, probably because of the difficulty on making an exact 1.5mm hole in the dead centre. Two minutes on the lathe and the hole was made. The gear dropped onto the shaft and fitted perfectly. Rewind now worked.
When I started to investigate the 'no play' fault it seemed that the idler wheels tyre was too small so it wasn't meeting the drive spindle. I thought at first that the tyre had worn out so it wasn't engaging with the spindle. I then fitted a larger tyre over the old one as a temporary experiment. This made it drive but stopped the wheel engaging with the take-up spindle. I now looked on you tube for any help. One video showed a repair for the small gear and in the background I saw that the flywheel spindle had a piece of rubber on it to engage with the idler wheel. I had some neoprene tubing and fitted it over the shaft in the position where the idler would meet it. I now had play working. With a cassette in it played and did a fast forward but still no rewind. With no cassette the rewind ran ok but with any sort of load it stopped turning. I looked at all the belts and they all seemed to be Ok. I then saw what appeared to be a slipping clutch arrangement driving the rewind. I extracted this from the deck with the aim of refurbishing it. Alas the unit was crimped together and I could not take it apart. Eventually I managed to insert a length of small drive belt into the clutch area. This restored the rewind function.
The deck was now working correctly, I think that the slipping clutch on rewind might be a bit tight but it's the best I could come up with.
The repair took several weeks on and off, I hope the owner will be pleased.

Malcolm
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Old 19th Apr 2023, 4:50 pm   #2
Welsh Anorak
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Default Re: Sharp rt 3151

Glad it's going again.
The play driver rubber failing is a common fault. I've successfully used a similar item obtained from eBay as a "latex rubber tube slingshot" replacement - don't ask! A metre is probably enough to repair 100 machines...
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