Originally Posted by
peter
More information:
I have located the original installation instructions. One point made is that not all the sorb mounts are the same. One has to bear a greater weight due to the tonearm, and is of differnt type. Its setting depends on the type of arm used as well and it is necessary to remove the platters adjust, replace platters, measure, repeat intil the arm weight bias is correctly nulled out.
Steves includes a tip that simplified this, as you can adjust the spike pentration without having to remove the sub-chassis, which I did not realise.
I can scan the instructions for future reference if that is helpful. It is an interesting read from the design perspective, and interesting to compare with Steves instructions/tips. There is also a detailed instruction on how to replace the bearing oil, with more description of the materials used.
The bottom line as everone has said is level, level, level (three times for stability!)
that means:
1) Top base plate must be level (4 feet/spikes at the bottom)
2) sub-chasses must be level (sorb bolts/chassis spikes) according to arm weight
3a) bronze platter is level (and concentric to bearing) by 3 hidden bottom platter bolt heads and upper 3 grub screws (very tricky, 6 degress of freedom, not including angle of platter wrt bearing.
4) Upper acrylic platter has to be level (concentric) so there is no gaps to the bottom platter. Note that if 3 is wrong, this is impossible. The only way to adjust this is to turn the platter through various angles and use the cig-paper test to find the best angle with optimum gap, OR, if its not level then repeat 3 until it is.
Perform wobble checks
Install arm/cart.
I had a problem with the sorbothane deforming in a no time. It occurs that I tend to have the turntable powered up 24/7 so the heat from the power-supply board could have accelerated the deformation, so the moral is "turn it off when not in use".
Sincere thanks to everyone for contributing so far.
Peter.