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are AR77XB platters balanced?

N

Neil Brown

New Member
I picked up an ar77XB in excellent condition before Fedex got a hold of it and its now more of a project. However something I notice on the outer platter is what looks like a small piece of metal glued on the outer part of the inside. I had never read these were balance like that by AR.Has anyone else spotted this or has the table been monkeyed with by someone previously?
 
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I’ve seen balancing weights on AR tables of all stripes. Not unusual at all. The trick is finding the best point where the inner and outer platter balance. A sharpie dot on both once you do will save you a lot of time.
 
I answered you on the other forum you posted this to. It is factory. Both my XA platters have this. I've owned one of them since new 50 years ago.
 
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Neil Brown said:
I picked up an ar77XB in excellent condition before Fedex got a hold of it and its now more of a project. However something I notice on the outer platter is what looks like a small piece of metal glued on the outer part of the inside. I had never read these were balance like that by AR.Has anyone else spotted this or has the table been monkeyed with by someone previously?
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standard balancing. all the outer platters have it
 
Many other tables of the time have something similar, though most drilled out little bits of metal.
I think casting techniques may have gotten sophisticated enough that balancing wasn't necessary in the later years of vinyl.
 
Kinda like balancing tires ... nigh impossible to get perfect without a bit of tweaking.

** Before you get too deep into it, make sure the platter is set right on the spindle. A lot of tables will have slightly conical spindle that locks onto the platter when you install it. Secret is to just line up the hole and drop it in place.

PS ... my Mitsu also has the mat marked for the correct orientation.
 
The spindle is cast into the subplatter on ARs - the platter is a a two part affair, which is why people worry about the relative alignment of the outer platter and the inner subplatter.
I do not know if the subplatter is also balanced, if it is, one wonders about the need for all this worrying - presumably balancing of each part makes them pretty uniform in mass distribution. I have no doubt, though, that it can be satisfying to improve on things, and if you think you hear an improvement, it sounds better to you. Certainly this is one tweak that costs no money to try.
 
Does balancing even matter? We're talking about a 350g casting that spins at less than 100 RPM. Math a little, and you may discover that it's about as relevant as oxygen-free copper.
 
Watthour said:
Does balancing even matter? We're talking about a 350g casting that spins at less than 100 RPM. Math a little, and you may discover that it's about as relevant as oxygen-free copper.
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the copper is "oxygen- free" because the iron has been removed from it during the smelting process. how many "N's"?........depends on how much was in the ore to begin with.
 
I suppose there's ways you could see if you're at least close enough. Here's a handy dandy platter balancer, and it even works good with lawnmower blades! <G>

lawnmower-rotary-blade-balancer-ideal-for-hayter
 
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