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November 17, 2004
16) 
"Today the motor went back to its old place. The motor is in good condition, no noise no hum. I assembled a new clutch. The motor tower was painted new some days ago. The rest was just cleaning. The adjustment mechanism was a little rusty. I eliminated all rust in a chemical bath normally used for cleaning gold surfaces.
17) 
That Motor
Hi Rolf
That motor sure does look very much like the motor I have in both of my TD160s. A mk1 and mk2. I'd like to gain some general understanding about the pitch control used on this model. How similar would it be to those used on the TD126 and TD125 models, for instance...?
-Steve
Hi Steve
Indeed, the motor has the exactly same housing like the 160 up to 166, the 125
Mk II and TD 126 (except the TD126 III) models. But inside it is completely
different. The 160 Mk I and II are using 110 volt coils (more impedance, high
voltage, low current). The Prestige motor is most similar to the TD 125 II motor
but lower in impedance, also low voltage, but higher current. Therefore a higher
powered amplifier is used at the electronic output stage. More torque is the
result, ....needed for the higher platter weight.
There is another big difference to the smaller models. The TD 160 speed is
coupled direct to the mains frequency. The TD 125 and 126 (except TD 126 III)
are using own internal oscillators for the the motor drive. These oscillators
are very precise, but they are running free and any mistake is added on to the
next turn.
Only 4 Thorens models are operating with a speed return path. First the 126 III
(tacho generator) then the models TD 524 / 738 (my next project, it is
completely different to all other Thorens models - much more near to EMT),
Prestige and Reference. The return path is realized by a low magnetic rubber
ring under the drive platter and a printed coil direct under this platter. The
magnetic ring will induce a very low AC voltage into the coil during rotation.
The AC frequency of this voltage is compared with the selected speed and the
oscillator is driven by this comparison. More details will coming up during next
week, when the rework of the Prestige bearing, center spindle and drive platter
is planned. But first, over the weekend, the floating chassis will be optimized.
The upper chassis plate (the dirty, ugly unpainted one) will be replaced with a
brand new one from "treasure stock". I have only two of these original
plates, original painted, one for this table....
Of course it is possible to add Prestige technology to an 16x, 125 or 126
(except 126 III). But I have no electronic components, not even for the actual
project. I am forced to reproduce them. I have all needed blueprints and I will
do it. But that will be another chapter.....
Best analog regards
Rolf
November 20, 2004
Disassembly of the floating chassis made of of the following parts:
- 4 upper aluminum bearing blocks
- 1 main steel floating chassis frame
- 1 upper face plate made from aluminum with a high gloss dark grey metallic enamel
- 1 rubber interface between point 2 and 3.
- 2 wooden outer frames with a brass (with gold plated) clamp on the backside.
17A) 
most of the parts and one of the screws that takes 2,3 and 4 together.
18) 
If all of these screws are removed, you can separate the upper face plate from
the floating chassis. The rubber interface will remain on the faceplate,
but it can easily be removed. It is not fixed in any way.
19) 
The rubber interface and face plate are separated.
20) 
Downside of the aluminum faceplate.
21) 
Surface detail shot of downside faceplate.
22) 
Removing the upper bearing blocks from the floating chassis plate. Notice
the wood structure.
23) 
Some of the bearing block screws are damaged. They will be replaced by
original ones from stock.
24) 
Line-up of the four upper bearing blocks before the rework.
25) 
Unscrewing the wooden outer frame.
26) 
So many screws. From left to right, bearing block screws, wooden frame
screws and faceplate screws.
27) 
The treasured "stock parts" get into the game. The last
inventory 1995. Counted, packed and stored for nearly 10 years.
28) 
Another one: 7 826 023 What a number. Only 2 brand new parts of this
are available worldwide and this is one of them.
29) 
Christmas in November. I do not (yet) know the condition of the contents
of these packages.
30) 
A perfect mirror-like surface.
31) 
The future of the Reference II in the mirror of the past. Time meets time,
20 years in between.
32) 
Back to reality. Worms!
This upper wooden chassis must be replaced. I'm glad to have a new one in
stock.
33) 
6 826 001 was my rescue number in this situation.
34) 
Pre-drilling for a handful of screws...........
35) 
Again the upper bearing blocks. Cleaned and polished.
36) 
I did not mill away any material. I just want to stay alive this surface.
37) 
The floating chassis with new wood, some new screws and everything else
original.
38) 
The original rubber interface will be used.
39) 
First Contact. The new face plate gets in first touch with the reworked
floating chassis.
40) 
Screwed together.
41) 
First positioning of the new parts. First, comparing the colors, and the
new wooden parts are matching exactly.
42) 
Same scene from side view using flashlight. The floating chassis has a
little backward move because only one bearing is assembled and, of course, not
adjusted yet.
Over the rest of the weekend I will invest some time into the main platter bearing. On the first look it is completely damaged and I will search and gather together the parts needed to build up a brand new one.
Late this evening I found some time to look after the base plate of this turntable. I found out that two types of turntable stands have been used in the past. Both are similar in dimension, function and outfit (matt black painted) but they are different in material. I found three steel made ones and one made of brass. So I went into stock to look after the situation. All stock parts are made of brass. I like this material very much so I decided to polish away the black painting and give it a new clear coat over the brass and with a new original felt inlet. Looks great....
86) 
An original steel stand. (foot)
87) 
The two backside reworked brass stands. Re-machined and clear
coated.
89) 
The renewed turntable stand.
December 11, 2004
My first plan was to bring the Prestige playing this weekend, but there is not enough time. This evening I took together all bearing parts of the suspension. On my earlier suggestion I was thinking that bearing balls must have been used at the bottom of each main bearing bolt. Today I found them. Before trying the first assembly, I took some pictures of the situation.
103)
All parts of one of the four main bearings from downside. All parts right
of the main conical spring are mounted in 90 degree angle, left turning.
All these parts are part of the floating chassis. The parts on the left
side are parts on the basic chassis. The two big screws middle-left will
fix the construction to the base plate. The floating chassis is mounted on
the upper right aluminum block.
104) 
Same parts from side-view.
105) 
Same parts from top.
106) 
One complete bearing chassis assembly block from downside. All weight will
rest on that little steel ball left-side.
107) 
The complete unit installed. The right conical spring will hold a triple
layer layout. Rubber - aluminum- rubber, plus two steel plates to carry
the mounting screws. The two empty bolts will carry the floating chassis.
Happy
about the result, I assembled all four subchassis bearings. The chassis is
swinging perfect in low amplitudes, but on higher amplitudes it gets in hard
contact with something inside........I found out the reason and the parts
touching together. The screws up left and up right shown in photo #6 
half behind the front suspension MUST be removed. Otherwise they can get
in contact with the chassis bearing system on high amplitude swinging.
Fault of the system...I will disassemble everything of the floating chassis
tomorrow, because there is no other chance to reach these screws in this
stadium.
December 12, 2004
Today I found a few hours time for the Prestige. First, I disassembled the floating chassis again to remove the disturbing screws. This time including all platter drive elements, Tacho-generator and interface board. After this work the turntable should be able to be leveled and be rotated by its own drive system.
Level adjusting runs very well. I never saw a suspension swinging perfectly vertically like this Prestige. Also, horizontal vibrations are eliminated. The resonance frequency of the floating chassis is very low. I suggest around 2 hz vertically.
The drive system works perfect.
But two new problems appeared:
First. The main platter. On static view his surface is perfect -- but in rotation his surface looks nervous. Maybe a matter of painting (not constant thickness of paint) or of the platter itself. I decided to re-machine the platter and paint anew.
Second. The floating chassis is out of center right-side. There is a clockwise spin. If you look from above, you will find it in good position from left, but all other positions are turned clockwise around the front left bearing. On rightside front, the difference is approximately 3mm. Actually, I do not know the reason. Because the chassis mounting points are fixed and not adjustable, I think of a spring problem or a spring mounting problem.
The stud that carries the weight of the floating chassis is allowed to rotate, but only during the height adjustment process. In use, a rotation is forbidden by the pin coming up from the lower bearing block. Also the rotation of the top bearing arm is blocked by this pin. All these parts are only allowed to be adjusted in vertical direction -- and all these parts are fixed on the main chassis. So I think the spin problem is caused by the springs or spring assembly.
108) 
Photo #108 shows the problem. Sorry about the point of view, but it was
very difficult to get my camera inside a playable Prestige turntable.....
There is no given exact position to fit the main spring to the upper and lower bearing arms, but I will find out. This picture shows the real assembly situation front left on a playable Prestige. Top is upright. You see the main bearing stud below the main spring, adjustable through a hole in the upper chassis. Visible on the right side. The leading pin is visable below the main bearing stud. In the background the balance spring appears (not hanging into the the screw in the lower bearing block). Down left you see the lower bearing block part of the base plate. Up left the upper bearing block can be seen. This part is connected via the lower bearing arm (front side photo #107) to the floating chassis. I think the adjustment will take some hours time....
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