[Audio Empire]

On Tue, 11 Jan 2011 10:42:24 -0800, Arny Krueger wrote
(in article ):

"Trevor Wilson" wrote in message

Dick Pierce wrote:
On 1/5/2011 6:54 PM, Trevor Wilson wrote:
wrote in message
...
I have an approximately 10 year old Pro-Ject 1.2
turntable. Over the last year, the big heavy platter
has begun scraping as it spins, and has finally ground
to a halt. If I elevate the platter, by putting a shim
(two old CDs) between it and the sub-platter, that
elevates it enough that it spins again, but with lots
of wobble. Obviously not an ideal fix.

I don't know what's happening, but I'm guessing the
sub-platter (which is what actually spins, driven by
the motor/belts) has descended/sunk a bit.

Has anyone experienced anything similar with this
turntable? Is there any way to fix this problem?

Thanks in advance!

**Common problem with some of the Pro-Ject TTs. The
platter sags! Remove the mat and look at the platter
from the side. You will probably note that the outer
rim has saged, relative to the spindle. Cheap, crappy
die casting I guess.

Are you SERIOUS? The platter has sagged? Please!

**I just spoke with a mate who is very experienced in all
kinds of metal-working technology. He said that such a
problem, whilst unusual in good quality castings, is
certainly not unheard of. Apparently, die casting causes
all kinds of stresses in the material, which if not
controlled, can lead to cracking and/or the deformation I
described.

In order for that sort of thing to happen, the casting has to be very thin.
Usually turntable platters have far more thickness than is needed for
mechanical strength, in order for there to be enough weight. I remember the
3.3 pound "lightweight" die cast platter for my AR turntable. It was pretty
uniformly 1/4 - 3/8 inch thick. It would never sag under its own weight.



The AR tables were great products and were (mostly) very well made. In fact,
I've a buddy who modified the sub-chassis on his late-sixties vintage AR
'table so that it could take another arm (the original AR arm was the
'table's Achilles heel - it was lousy) and his modified AR was every bit as
good a Linn Sondeck LP-12. In fact, except in a few details, they were almost
identical in the way they were designed. He installed an AudioQuest PT-6 arm
(made by Jelco in Japan) on it, and as far as I know, he's still using it.
When Teledyne bought AR, they changed the table somewhat. Instead of a having
a straight-sided 12-inch platter, the Teledyne unit had a flared platter that
was larger in diameter at the bottom of the rim than it was at the top. They
also canned that awful Edgar Villchur arm in favor of a jeweled gimbal-mount
arm from a Japanese source.

The tables were so well made, that there are literally thousands of them
still in use. The original units used two tiny "clock motors" and they are
impossible to get belts for anymore (so I've been told) but the later,
single-motor units (XA, XB etc.) still have belts available from places like
"Needle Doctor" for about $20.

I doubt if any AR platter has ever "sagged".