1972 JVC (NIVICO) 5240B Turntable

snap, crackle and pop
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wolfie62
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1972 JVC (NIVICO) 5240B Turntable

Post by wolfie62 » 07 Dec 2018 00:58

I just got this table on a trade.

It’s a belt drive, auto-return model. It has a rather unusual (to me) tonearm configuration.

Any one know this table, and is it worth restoring? I do have the service manual for it.
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musicmn
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Re: 1972 JVC (NIVICO) 5240B Turntable

Post by musicmn » 07 Dec 2018 16:52

Hi, that turntable looks a lot like and old pioneer pl50 with the cover over the belt shifting mechanism on the front left side. It appears to be in very good shape and to me all these old turntables should be serviced and brought back to life. It may not be worth much if you are planning on flipping it. But it's just fun to work on them then play a record or two on it to see how it preforms. I bet it will sound better and preform better then most of the junk out there that's being made in China today. The only issue with these old AC motor driven turntables is that the platter drive belts being made today can cause platter speed issues. You may have to buy more then one to experiment with to get the platter speed correct. If you decide to service this one make sure to clean and lubricate both the upper and lower motor bearings and the spindle. That way getting the platter to the correct speed will be easier. It's a very nice looking basic turntable, good luck and I hope this helps.

wolfie62
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Re: 1972 JVC (NIVICO) 5240B Turntable

Post by wolfie62 » 07 Dec 2018 20:16

I probably need to upload the copy of the service manual I have. I don’t plan on flipping it. It’ll be part of my legacy table collection.

Wondering, since it used a synchronous ac motor, if I will get better speed stability by using an ac inverter to drive it, since it uses the mains 60 Hz wave for speed stability.

I’m still trying to make sense of the “outrigger” weights used for anti skating and horizontal arm balance, in addition to the conventional counterbalance weight.

DasherF
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Re: 1972 JVC (NIVICO) 5240B Turntable

Post by DasherF » 08 Dec 2018 05:02

...absolutely, any table that looks as good as this one deserves to ge restored, definitely! It has a lot of PROBablites.
PROBably why I have 16...all mine have a good home...so does your JVC...good luck with the restoration!

nat
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Re: 1972 JVC (NIVICO) 5240B Turntable

Post by nat » 08 Dec 2018 16:34

The outrigger or lateral balance weight is supposed to compensate for the side to side imbalance of the arm caused by the bend in the arm, which puts more mass on one side of a line drawn at a right angle from the vertical arm bearings. If you have the weight, stick it on - the position is not critical, and often its just mounted about a third of the way out, but if you are concerned, tilt the table with the left hand side up, and adjust until the arm (with the cartridge on it and tracking force and antiskate at zero) doesn't move side to side. If you don't have the weight, don't worry about it - many users think they resonate and cause more problems then they are worth.
Belts need to the right size - length and height are obviously important, but thickness matters also since the pulley and belt act like the pulley diameter is in the center of the belt. So a thicker belt will give faster speed.
Unless your ear is sensitive to absolute pitch, a small amount of error is nothing to worry about since you can't hear it even if you can see it with a strobe disc. In a perfect world, all records would be cut at the exact right speed, but that is not the world we live in - most records are not at correct speed, so whether your turntable is dead on or not almost doesn't matter - its a crapshoot. If you do have absolute pitch, you probably need a table with variable speed.

wolfie62
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Re: 1972 JVC (NIVICO) 5240B Turntable

Post by wolfie62 » 08 Dec 2018 17:47

Antiskate: I don't see any adjustment on this. the 2 weights are at 90 degrees from each other, and I don't see any adjustment, as they are not removable. No mention in the service manual.

As an engineer, reliability engineer, the belt thickness plays no part here for speed ratio from the belt pulley to the platter pulley. For chain drives, yes, there is what is called " pitch diameter." Not with a flat belt. Belt thickness plays a part in durability and flexibility. As long as the belt is smooth on inner surface, consistent in thickness and durometer, it will make no difference in driven speed of the platter.

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