Thorens motor knocking/tickling noise - solved

[Zen Mod]

well - just found culprit for tickling sound in Thorens motors ;

I made extensive research on net and all I can find are unfortunate attempts in solving that issue

rotor magnet cylinder is filled with two equal plastic cores/bushings ;

but - after many hours of operation - there is slight looseness between plastic cores and magnet and that is reason for magnet "rocking" on cores during revolutions

solution : buy some super glue , and pour some of it on both tops of magnet cylinder - between magnet and shoulders of plastic .

problem solved

 

[Zen Mod]

you must open the motor , drilling points where three stubs are pressed on motor body , and later you must replace them with new ones ( use generic tapped spacers cut to same length) .

whatever you do after removing these tree stubs - use just hands ; you do not need any tool ,and that way you're preventing any damage possibility .

magnet is just pressed on spindle ;

as reminder - there is double metal washer on each side of magnet/shaft combo

dismantle everything and be careful to put magnet back on spindle in same orientation - because of rotating orientation ; anyway - side with shorter center hole part and additional small plastic "ring" is lower -bottom side

clean/wash bearings and shaft with benzin or alcohol

put several drops of super-glue right where I mark with red on attached pic - between ferite and plastic shoulder; glue both sides , off course

wait half hour before motor completing procedure

use graphite grease for shaft/bearings - thin oil is story for little kids , obviously .

 

[kevinkr]

Which motors specifically does this affect?

Obviously not a TD-124, 121, 224, 135..

I never had this problem with my TD-125 either..

More useful tip if you let people know which motors it affects.

 

[Zen Mod]

all looking like this ( pic from VE ) ;

if I remember correctly - there are both 110Vac and 13Vac ( via controller) versions

An externally hosted image should be here but it was not working when we last tested it.

 

[kevinkr]

The motors in TD-125 MKI and MKII are quite different than the motor shown so I can't say whether or not this fix would work in them, OTOH I haven't encountered problems with either version of the TD-125 motors. (Different voltage versions)

 

[iron_gr]

I've opened mine today (Thorens TD-160 Super) but I cannot feel that the magnet is loose.

So this knocking noise is from bushing wear. I already did the "lifting of the spindle" DIY which eliminates the knocking but I wanted to see if I can get rid of it once and for all.

 

[Raka]

Lifting of the spindle? What's that? I'm now working on a PS for my TD160, and I think I'm missing this "lifting of the spindle" thing. Can you elaborate on this please?

 

[iron_gr]

Hi Raka,

if your motor doesn't make any noise then there is no need to bother with this.

Some links with more info:

http://www.vinylengine.com/turntable...p?f=17&t=25437

Unfortunately the images that showed what needs to be done are removed. In my case I used a T-nut and a ball bearing which is hold in place with a screw.

There are also some people who are selling kits or giving some instructions where to find one. Take a look:

http://vinylnirvana.com/2012/10/tip-...ber-22nd-2012/

SRM TECH

Some forum posts with additional details and opinions:
http://www.audiokarma.org/forums/sho...d.php?t=602461

http://www.audiokarma.org/forums/sho...=411709&page=2

 

[user510]

you must open the motor , drilling points where three stubs are pressed on motor body , and later you must replace them with new ones ( use generic tapped spacers cut to same length) .

whatever you do after removing these tree stubs - use just hands ; you do not need any tool ,and that way you're preventing any damage possibility .

magnet is just pressed on spindle ;

as reminder - there is double metal washer on each side of magnet/shaft combo

dismantle everything and be careful to put magnet back on spindle in same orientation - because of rotating orientation ; anyway - side with shorter center hole part and additional small plastic "ring" is lower -bottom side

clean/wash bearings and shaft with benzin or alcohol

put several drops of super-glue right where I mark with red on attached pic - between ferite and plastic shoulder; glue both sides , off course

wait half hour before motor completing procedure

use graphite grease for shaft/bearings - thin oil is story for little kids , obviously .

What model of Thorens is that rotor out of. It doesn't look like any Thorens motor-rotor I have seen.


Example photo from a TD160 motor:

more photos of the motor:
Bogdans Motor

 

[abauer48]

Knocking sound solved

I'd like to post my solution for the knocking sound problem on my Thorens TD 160 which I found so irritating that I just had to try something. I didn't trust myself to disassemble the motor so I applied gentle pressure on the spindle below with my fingernail and noticed the knocking stopped. I doubted that anything was loose within the motor itself. I'd advise a more professional solution than mine, e.g. a kit from eBay. However I'm pleased to say that my idea brought success without the overhead of postage and customs duty.

First buy a few small identical springs. Squeeze one side to just fit into one of the motor holes. Use stiff isolated wire (e.g. Bonsai wire) and loop it through the squeezed spring end:
... picture 1 ...
Pull it through the motor hole:
... picture 2 ...
until it stands upright:
... picture 3 ...
twist the isolated wire to prevent the springs from coming out:
... picture 4 ...
The 3 springs stand upright on the underside of the motor:
... picture 5 ...
Saw a triangular piece of plastic or stronger material, make three holes and loop the springs into them:
... picture 6 ...
If the length of the springs is right, gentle pressure should be applied to the spindle:
... picture 7 ...
It's important that only the tip of the spindle touches the transparent surface. A small piece of glass could be glued onto it if you want a less abrasive support for the motor spindle. That's it! Very makeshift, but costs almost nothing to try out. I'm very happy with the result!

 

[abauer48]

Knocking sound solved - addendum

The plastic was far too soft, of course. I had to glue a piece of thin glass (cut from a mirror) - see picture. I think this will last 🙂

 

[AndrewT]

well - just found culprit for tickling sound in Thorens motors ;................

rotor magnet cylinder is filled with two equal plastic cores/bushings ;

but - after many hours of operation - there is slight looseness between plastic cores and magnet and that is reason for magnet "rocking" on cores during revolutions..............

.................
So this knocking noise is from bushing wear. I already did the "lifting of the spindle" .................

Lifting of the spindle? What's that? ............

........... I had to glue a piece of thin glass (cut from a mirror) - see picture. I think this will last 🙂

I think all these posters are referring to rotor end float.
End float allows the rotor to sit anywhere between the end stop limits.

It can move between the end stops depending on load, external vibration and supply voltage.

The solution as found is to limit end float. And use a little bit of oil in the remaining end float gap to damp oscillation in the remaining tiny gap.

The gap must not be zero, otherwise temperature expansion could in worst case lock the motor, or wear out the end stops and the excessive end float returns.

 

[abauer48]

I use the spring loaded plate to push the motor spindle (aka rotor end float) to the top - there's no restriction on the gap. In my case this eliminates the knocking sound. I have a slight concern that motor spindle now rests on the upper limit instead of gravity pushing it downwards, i.e. some other part may wear out. Anyway, if it doesn't last I'll likely invest in a Thorens TD 203 using my current AT OC7 MC-cartridge.

 

[AndrewT]

Gravity still pushes down on your support plate.

It's the oscillation between the end stops that you have attenuated.