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Old 20th October 2012, 04:03 PM   #1
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Default need help with problematic JVC turntable

Hello all,
my trusty curb-find L-A21 turntable has been acting up lately. When the record ends, the auto-return mechanism seems to "backfire". The arm will return to its intended position but then goes back over the reconrd, and in the last event, decided to drop down, violently on my Allman Bros record(or whichever vinyl circle tickles my auricular fancy).

My first guess was "the belt's loose and I have to replace it". But on further inspection I found the belt to be in decent shape. Also what I discovered later negates the belt theory. So I have decided to take it apart and see just how this mechanism works, and in hopes of finding the problem. I discovered that the arm "rotor" if one can call it, was loose on the arm axle (the axle with the bearing). I figured this was most probably the culprit, since the rotor body, which has a small setscrew, was cracked at the setscrew junction. I promptly re-melted the plastic with a blowtorch (yes, I know) and re-installed it on the axle. Same problem.

Later I realized that the mechanism itself (the big gear, the pushing-connecting rods, etc) was not behaving properly. I simulated the arm-return operation by turning the gear manually. When the arm returned to its resting position, the gear had not yet finished its rotation. but when the gear is at the point where the arm is at its resting position, the puch rod no longer exerces a force against the arm, so there's nothing that should make the arm want to go back on the record. It's as if the arm is being pushed back the the record.(I thought by anti-skating device, but I don't think so, it seemed to be unresponsive and did nothing to solve the problem).
Anyway I'll post a video on U-tuBe for those interested I'll call it "the hopes and perils of the Nippon pennysaver vinyl rotator". No kidding I'll post a link when it's up.
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Old 20th October 2012, 04:15 PM   #2
kevinkr is offline kevinkr  United States
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Moved to analog source since this is a turntable.
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Old 21st October 2012, 02:10 AM   #3
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Indeed. thank you for fixing my mistake.
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Old 21st October 2012, 05:53 AM   #4
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Older mechanical beasts often have problems with lubricants drying out and stiffening up. "Disassemble clean and lube" usually fixes it unless something actually broke from the stress. If you can't find a manual for it, learn to take good close up pictures and take a lot of them before you pull it apart. I used to do a lot of turntables 35 years ago.

Don't slather if full of lubriplate or WD-40. A good light machine oil like Nye Oil II will do wonders.

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Old 21st October 2012, 06:44 AM   #5
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Thanks Stratus46. Actually I thought I took some pictures of the inside but Iguess not. I only have videos, which are too big to post. In any case I don't know where to lube it, besides everything seems to rotate or slide just fine...

Once I get a few pictures you'll all see. literally! lol

thanks
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Old 27th October 2012, 05:45 PM   #6
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Default toshiba turntable

Hi people

I decided to add to this thread as it has to do with my obsession of turntables. (I only own about 8 of them)

So I have a nice Toshiba SR-250 that a friend rescued from a certain curbside death, and it has sat in my VCR cabinet for about four years. all it needs to be functional again is a headshell, a belt and... a platter. The two first items are easy to obtain, the platter however, is a different matter (I don't know if a pun is, or should be intended)...

I saw on some craigslist add for an SR-250 that Toshiba was made by Toshiba "Shibaura". does anyone know who that is (was)? I mean the mechanical peices for those turntables were probably made by one metal manufacturer in japan, I am guessing so they would have used these to more than turntable maker (OEM), such as CEC, JVC, Matsushita, Sony (well, amyeb not Sony), Toshiba, etc.
So what I'm trying to get at is, which turntable from another manucfacturer will have the same characteristics as my Toshiba?

I know it's a longshot, and I'm depending on the very precise knowledge of a very small part of the community, but someone out there must know this.

If no one does, then I'll go by meeasurements and find a substitute from an ebay seller.

thank you all!
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