Vintage DD turntables. Are we living dangerously?


I have just acquired a 32 year old JVC/Victor TT-101 DD turntable after having its lesser brother, the TT-81 for the last year.
TT-101
This is one of the great DD designs made at a time when the giant Japanese electronics companies like Technics, Denon, JVC/Victor and Pioneer could pour millions of dollars into 'flagship' models to 'enhance' their lower range models which often sold in the millions.
Because of their complexity however.......if they malfunction.....parts are 'unobtanium'....and they often cannot be repaired.
128x128halcro

Another week rolls by and no progress.  Maybe I'll hook up with my Tech later today.  One of the problems with coupling a mat - do you want a "permanent" solution like a Goldmund mat, or maybe introduce another material like copper, which might also need some coupling. Maybe there's an adhesive that will hold it in place which is easier to change out if you want to experiment?

Here's the deal with the Kenny type AR compound. It's said to be ground limestone and polyester resin.  That's kind of a general description. Polyester resin varies from auto body filler to driveway coating. They start calling the stuff resin. Apparently there are mucho variations. Maybe I should try Bondo first and call the table "Big Pink". I suspect a driveway coating type might be better. A 5 gal. bucket requires a hand truck, but you can get it already dyed.  Ground limestone comes in a 50lb. (?) sack and is the stuff they use for lines on a football field.

Okay, a little experimentation is in order here. I suspect this should be done in one pour. If you're working with cement or concrete you can build it up, like sculpting with clay. I think this is more like a casting. What proportions? Weigh the component parts and try it?  It's not as straightforward as you might think. Meanwhile, I only have so much time before South Jersey is underwater and Front Street in Philly is beach front property.  No joke. The rate of ocean rise is greatly underestimated. Maybe I'll move to the Rockies. I hear their water is extra poisonous due to the old mines filling up with water and heavy metals infiltrating the supply. Sounds like rock and roll to me.

neo McFleibster

Fleib
Many years ago I decided to completely replace the platter on my SP10 MK3
The new one consists of a trilaminate of acrylic on the top 15 mm of lead and then duralium.
The  duralium interfaces with spindle and spigots to the lead and acrylic keeping thinks nicely centered. It also houses the rotor magnet and speed sensor/commutation assembly.
I spent a lot of time before hand experimenting with glues. I settled on an epoxy where I adjusted the ratio of the two parts to create a glue that was around the same hardness as acrylic. The idea being to simulate a laminate where the lead was fused to the acrylic. This rather than introducing a lossy layer of glue between the two materials.

The total weight is around 10kg as per the original. Moment of inertia is slightly higher.

I like the result. That said back then I did not experiment with metal or graphite mats. I now know that a SS mat works extremely well on the SP10

cheers 




Hi Richardkrebs,

Cool platter.  The speed sensor moves with the platter?  Seems a little strange.

Regards,

Fleib
The speed sensor consists two parts..., 
The sensor coils which are stationary and a toothed magnet which is attached to the platter.
Sorry, I wasn't clear in my earlier post.

Cheers 


Richard, What interests me most is WHY did you decide to make an entirely new platter for the Mk3?  And what are the consequences to how it works associated with incorporating one half of a speed sensor device into the platter?  (What's a "toothed magnet"?  I've never been bitten by a magnet.) Did this entail a basic change in the circuitry?