I would not expect this to be too repeatable over time and temperature, any change in drag due changes in viscosity and clearances due to temperature variations would affect this.
Just thought I would mention that I damped the inside of the bell, err zamac platter on my TD-124/I with some self adhesive cork sheet. I cut 8 (or was it 10??) small trapezoidal pieces that I stuck along the inside of the casting. It seemed to help a little bit, but the zamac platter still really rings like a bell - even with the cork. I can't help but feel that something like deflex judiciously applied could be better. This results in a very audible coloration, changing to an iron platter on my MKII was a fairly shocking improvement. Leaves you really wondering what Thorens was thinking about when they designed this particular platter. (Certainly not about maintaining the performance of their top of the line product.) It is really inferior.
My thought was that if it behaves as you suggest (not repeatable) that would be a good thing and would rule out significant platter imbalance or oddly worn spindle bushings, etc. i.e. some severe condition that caused the platter to "settle" into a particular orientation (pendulum effect). It just strikes me as very odd that the platter would reverse at all, given the platter's reported to be level.
Or am I making too much of this?
I've noticed sporadically that both of mine seem to drift backwards momentarily usually no more than a few degrees before stopping. Most likely explanation I think is eddy currents induced in the platter by the eddy current brake magnet, I've never paid attention to it until now.
I don't think there is a problem. I don't usually observe this on the MKII as I usually engage the brake on the top platter on this table when I shut it off and remove the last record of the night. The MKI does not have a top platter (long story, but I am basically not willing to pay hundreds of $$ for one particularly with the current crummy zamac platter) - composite of zamac, glass and a gem dandy mat. (Almost dead enough)
I don't think there is a problem. I don't usually observe this on the MKII as I usually engage the brake on the top platter on this table when I shut it off and remove the last record of the night. The MKI does not have a top platter (long story, but I am basically not willing to pay hundreds of $$ for one particularly with the current crummy zamac platter) - composite of zamac, glass and a gem dandy mat. (Almost dead enough)
If it's only a few degrees, sure I wouldn't think anything of it either. Hadn't thought of the eddy current brake, but that seems a sensible explanation.
I was assuming that a huge backward swing. In such a case, wouldn't measuring for any play (rocking) in the platter due to worn spindle bushings make sense? Check the play at a few spots to see if the wear may be uneven? I would think that the combination of soft sintered bronze and heavy platter could, if the turntable had been mistreated during transit/shipping at some point, result in the bushings being out of round. Does that seem feasible to you?
fwiw, I have not observed this behavior. The TD124's I've had over here just do a gradual coast-down type of free spin. It goes slower and sloower, and sloooower and so slooooow and then,........you'd think it should stop but.... then finally, afterward,.... it's not moving anymore. No reverse motion at all. Just forward, then nothing.
-Steve
Thank you for comments.
Platter is level , everything is cleaned and lubed with extra care. It happens every time it stops .it not visible if someone else operates the tt. When I was checking the coasting time , then I saw that very slow turn to the opposite direction of 1 second.
Maybe it is an example of the...law of action reaction of Newton theory? I am not Physics fanatic but I am just thinking about that theory I might remember from student times 38 years ago.. If that has to do with my platter turn, that means that frictions are low and that is a good scenario. If not then the platter is not perfectly centered ..and that is a bad scenario ... Or it might be the eddy brake magnet that attracts a little bit the iron player ?
I share my thoughts with you who are experts and check everything that has to do with 124 .
I was always wondering why thorens used the nylatron thrust platte that after some hours has a pinpoint wear sign which means that frictions have started to take place...But even though when bearing was ful of 5-30 synthetic oil I noticed 2 minutes coasting time.Noe with 3 drops of Schopper oil (as he recommends) I notice 47 seconds .
As soon as I receive the new Teflon thrust plate I will let you know about the results. I have checked my friends bearing plates of different brands tts, most of those never cleaned and relubricated , but the wear of those was too light compared to my nylatron. So I have the worst plate
even I am taking care of it...replacing it with new , putting best types of oil..etc..
So..here are the 3 laws ...for my 124
Murphy's law...
Newton's Law
Law of attraction( I am afraid if something will happen to my lovely 124 and I attract it ...
Platter is level , everything is cleaned and lubed with extra care. It happens every time it stops .it not visible if someone else operates the tt. When I was checking the coasting time , then I saw that very slow turn to the opposite direction of 1 second.
Maybe it is an example of the...law of action reaction of Newton theory? I am not Physics fanatic but I am just thinking about that theory I might remember from student times 38 years ago.. If that has to do with my platter turn, that means that frictions are low and that is a good scenario. If not then the platter is not perfectly centered ..and that is a bad scenario ... Or it might be the eddy brake magnet that attracts a little bit the iron player ?
I share my thoughts with you who are experts and check everything that has to do with 124 .
I was always wondering why thorens used the nylatron thrust platte that after some hours has a pinpoint wear sign which means that frictions have started to take place...But even though when bearing was ful of 5-30 synthetic oil I noticed 2 minutes coasting time.Noe with 3 drops of Schopper oil (as he recommends) I notice 47 seconds .
As soon as I receive the new Teflon thrust plate I will let you know about the results. I have checked my friends bearing plates of different brands tts, most of those never cleaned and relubricated , but the wear of those was too light compared to my nylatron. So I have the worst plate
even I am taking care of it...replacing it with new , putting best types of oil..etc..So..here are the 3 laws ...for my 124
Murphy's law...
Newton's Law
Law of attraction
( I am afraid if something will happen to my lovely 124 and I attract it ...
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I just ran an experiment on my two tables; my MKII with the cast iron platter in three trials coasted to a stop and did not reverse direction; however the MKI table with the zamac platter did not behave the same way, in all three trials the platter counter rotated a few degrees before completely stopping, and is totally repeatable.
Both tables are level to within a few degrees. (Neither is better than the other) The platters are true.
My zany theory is that the iron platter has much higher resistance and hence eddy currents are less significant, it is also a magnetic material and is perhaps interfering with the magnetic field in ways I do not understand. The zamac is quite conductive and also non-magnetic so you have moving conductor in the field, current flows and develops a slightly repelling magnetic field that is bucking the eddy current brake pm field??
Given the recurrent discussion of coast time I thought I would report the latest time on the MKII which was 75 seconds with 30wt non detergent motor oil in the bearing housing filled to just above the lower bushing. (Essentially the spindle is running in an oil bath with oil in contact with the upper bushing as evidenced by some oozing oil if I put too much in to begin with.) The bushings are original and were in excellent condition, the thrust plate is mild steel and the ball bearing is the original steel ball.
The MKI with lighter zamac main platter, and glass top platter coasted to a stop in 45 seconds. This table has a fully rebuilt main bearing with bushings sourced from the fellow in Spain, lubricant is the same heavy 30 wt non-detergent oil and as in the other case the spindle is running wet, thrust plate is mild steel, and the ball bearing is the original steel ball. This housing only has a few dozen hours since the bushing replacement.
I suspect the lower mass of the zamac/glass platter accounts for a lot of the difference in coast down time.
The MKI with lighter zamac main platter, and glass top platter coasted to a stop in 45 seconds. This table has a fully rebuilt main bearing with bushings sourced from the fellow in Spain, lubricant is the same heavy 30 wt non-detergent oil and as in the other case the spindle is running wet, thrust plate is mild steel, and the ball bearing is the original steel ball. This housing only has a few dozen hours since the bushing replacement.
I suspect the lower mass of the zamac/glass platter accounts for a lot of the difference in coast down time.
Neither of my tables have significant bushing wear as indicated by a dial gauge at the platter edge. I have very recently replaced sintered bronze bushings in a main bearing housing for a friend where I estimate the play at the spindle flange was at least .010" which is way out of specification. (It was enough to be noticeable when manipulated by hand, something I rarely see with these bearings) Unfortunately I did not actually measure it, but the play was not noticeable after replacement.
I imagine the sort of damage you describe is possible if the box was dropped just the right way, but I've really only seen seized nylon or worn sintered bronze bushings so far. (Limited sample size of course)
I remembered that you check using a dial gauge which is what made me wonder what he'd find if he made the same measurements. While the fact that he's seeing a reverse on an iron platter, when apparently nobody else does is kind of a head scratcher, he mentioned "1 second" reverse, which at the slow rotation speed we see at the end, might still only be a couple of degrees.
If the spindle bushings, thrust plate etc. are about to get replaced, point's probably moot anyway, don't you think? Would be interesting to see if the rebuild makes it disappear.
Thank you for comments.
Platter is level , everything is cleaned and lubed with extra care. It happens every time it stops .it not visible if someone else operates the tt. When I was checking the coasting time , then I saw that very slow turn to the opposite direction of 1 second.
Maybe it is an example of the...law of action reaction of Newton theory? I am not Physics fanatic but I am just thinking about that theory I might remember from student times 38 years ago.. If that has to do with my platter turn, that means that frictions are low and that is a good scenario. If not then the platter is not perfectly centered ..and that is a bad scenario ... Or it might be the eddy brake magnet that attracts a little bit the iron player ?
I share my thoughts with you who are experts and check everything that has to do with 124 .
I was always wondering why thorens used the nylatron thrust platte that after some hours has a pinpoint wear sign which means that frictions have started to take place...But even though when bearing was ful of 5-30 synthetic oil I noticed 2 minutes coasting time.Noe with 3 drops of Schopper oil (as he recommends) I notice 47 seconds .
As soon as I receive the new Teflon thrust plate I will let you know about the results. I have checked my friends bearing plates of different brands tts, most of those never cleaned and relubricated , but the wear of those was too light compared to my nylatron. So I have the worst plate
So..here are the 3 laws ...for my 124
Murphy's law...
Newton's Law
Law of attraction
Surprising, as I said I do not observe this behavior with my MKII with cast iron platter, and only a very few degrees of reverse rotation with the MKI fitted with a zamac platter. In any event I do not think it is something to worry about.
I would recommend you try some additional oil in the housing wrt to spin down time, and check the play in the main bearing if you have or can borrow a micrometer. Look for some posts by Steve (user510) for details on how to do this. Also have a look at his analog depot website for many useful tips: TD124 Dept
My understanding and observation with a mechanic's stethoscope seems to bear this out - is that the nylatron thrust plate runs a bit quieter with the stock end cap. I am not running stock end caps and prefer the mild steel thrust pads since they do not wear much in use.
One of these days I will upgrade to ceramic nitride ball bearings, but I have not yet attempted to remove the retaining clip on the bottom of the spindle. Very early spindles incidentally do not have the clip. (Serial numbers from ~1100 on down. Yes I have worked on some extremely early TD-124s) I am not convinced that the clip is important except in the sense of retaining the ball during storage and assembly at Thorens back in the day, but have not had the heart to potentially trash a clip. At some point I will go for the upgrade and either successfully remove the clip or destroy it in the process. Since both of these tables will accompany me to Valhalla I don't care..
I am wondering about a teflon thrust plate, I had understood teflon to be soft and easily deformed, and I know it flows under pressure - not good qualities in a thrust plate IMO.. Very curious to see how you fare, noting that if it does not work well in the long run you can change it out, no damage likely, and it will be educational for all of us.
As long as you are reasonably careful, use the proper sized tools properly and exercise a little care it is unlikely you will do any serious damage to your TD-124. Unlike a lot of other tables should you have mishap there are a lot of spare parts available for this machine. Watch out for the metal speed change band, it can be broken and can also be the cause of potentially serious personal injury. (Sharp edges)
We can find out the reason I think if we place a glass platter from a rega or any other non conductive material and see what will happen.
Iron and zamac are conductive to voltage so it might be a type of eddy brake, as we have 1) the main turning conductive platter
2) a permanent magnet of the standard eddy brake
3) the iron plate near the eddy brake and some iron surfaces under the tt.
Could that combination be a kind of secondary very very low effective eddy brake system that causes that opposite direction too too slow turn?
That reverse motion happens to my iron heavy platter and also to Kevin's zamac plater. So it seems that the magnetic iron platter and the non magnetic zamac cast platter behave the same . I see that there is a common coasting time of about 45 seconds of Kevin's zamac platter and my iron platter and a common reverse motion. I don't know if that common coasting time has to do with that reverse motion issue.
Iron and zamac are conductive to voltage so it might be a type of eddy brake, as we have 1) the main turning conductive platter
2) a permanent magnet of the standard eddy brake
3) the iron plate near the eddy brake and some iron surfaces under the tt.
Could that combination be a kind of secondary very very low effective eddy brake system that causes that opposite direction too too slow turn?
That reverse motion happens to my iron heavy platter and also to Kevin's zamac plater. So it seems that the magnetic iron platter and the non magnetic zamac cast platter behave the same . I see that there is a common coasting time of about 45 seconds of Kevin's zamac platter and my iron platter and a common reverse motion. I don't know if that common coasting time has to do with that reverse motion issue.
My zamac platter literally ticks backwards, and for nowhere near one second, perhaps a tenth of that.
The only plausible explanation I can think of is severe bushing wear, but that I think would result in relatively long spin down times which he is not seeing. I do suspect that the bushings may have some issues and the lubrication may be insufficient if there is old lubricant lurking in those bushings.
I think the comparable spin down time Ongakos reports between his cast iron platter and my zamac one is coincidental - the zamac platter even with glass top platter is at least 1.5kg lighter than the cast iron set up so less stored energy, and the bushings in that main bearing are new and still running in - so more drag as a result. I am using a much heavier lubricant as well. (As I said I am not sold on long coast times being the be all end all mechanically speaking)
Something else to check is to make sure that the idler is disengaging properly from the platter rim. I carefully cleaned and lubricated the bushings in the speed change mechanism because of occasional binding issues on the MKII when I was bringing it back to life.
Surprising, as I said I do not observe this behavior with my MKII with cast iron platter, and only a very few degrees of reverse rotation with the MKI fitted with a zamac platter. In any event I do not think it is something to worry about.
I would recommend you try some additional oil in the housing wrt to spin down time, and check the play in the main bearing if you have or can borrow a micrometer. Look for some posts by Steve (user510) for details on how to do this. Also have a look at his analog depot website for many useful tips: TD124 Dept
My understanding and observation with a mechanic's stethoscope seems to bear this out - is that the nylatron thrust plate runs a bit quieter with the stock end cap. I am not running stock end caps and prefer the mild steel thrust pads since they do not wear much in use.
One of these days I will upgrade to ceramic nitride ball bearings, but I have not yet attempted to remove the retaining clip on the bottom of the spindle. Very early spindles incidentally do not have the clip. (Serial numbers from ~1100 on down. Yes I have worked on some extremely early TD-124s) I am not convinced that the clip is important except in the sense of retaining the ball during storage and assembly at Thorens back in the day, but have not had the heart to potentially trash a clip. At some point I will go for the upgrade and either successfully remove the clip or destroy it in the process. Since both of these tables will accompany me to Valhalla I don't care..
I am wondering about a teflon thrust plate, I had understood teflon to be soft and easily deformed, and I know it flows under pressure - not good qualities in a thrust plate IMO.. Very curious to see how you fare, noting that if it does not work well in the long run you can change it out, no damage likely, and it will be educational for all of us.
As long as you are reasonably careful, use the proper sized tools properly and exercise a little care it is unlikely you will do any serious damage to your TD-124. Unlike a lot of other tables should you have mishap there are a lot of spare parts available for this machine. Watch out for the metal speed change band, it can be broken and can also be the cause of potentially serious personal injury. (Sharp edges)
Thank you very much for advices,
I have changed the nylatron 3 times....The original after 50 years (and who knows the working time of the tt) has the same wear as the new nylatron after 50 hours of working time ...
I have all specific tools ,a stethoscope and also a stereoscopic microscope bought from Switzerland from mr Ernest Benz who owned Empire Scientific at that period of time . I will check with that microscope my ..worn collection ...of nylatron thrust plates when I will put the new Teflon ptfe next week and let you know. I checked the steel ball bearing that is in perfect condition just to be sure that it does not cause any wear to the thrust plates.
Yes the good thing is that thrust plate change is easy and reversible .
The bad thing are my collection of worn nylatrons...
The funny thing is when my wife looks at me to use many many times the ...stethoscope , the microscope , the magnifying glasses with their two LEDs on and some surgery tools for maintenance the tt....
She asked me ..." Is that a standard procedure that all audiophiles do in order to hear music through a tt ?"
But nobody and nothing can stop me from my true passion for the 124 ..!
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<snip>
She asked me ..." Is that a standard procedure that all audiophiles do in order to hear music through a tt ?"
I can relate, I have been teased unmercifully both here and by friends and family about my maintenance shenanigans.. Of course when they hear one working properly most times they almost get it.. lol
My experience with nylatron is that it wears rapidly initially and once it reaches a certain point the wear virtually stops. I reversed a nylatron pad in one of my tables at a certain point and was surprised to see that within weeks that it had worn to virtually the same point as the other side. I have seen this with brand new ones as well, for me it meant having to readjust the brake/platter lift mechanism which was annoying - no more problems since I switched to mild steel.
Well me, I just like to "tinker." It started with clocks when I was a kid. I really think that's a lot of why some of us enjoy working on turntables. They're mechanical beasts with lots (sometimes too darned many) moving parts. Little changes can produce big results.
As for the wife factor, she's just happy that there's something I enjoy doing. Besides, it's not like I won't pick up albums just for her, so I'm good!
Yes Kevin the wear becomes instantly.
The last time I changed the new nylatron which used for no more than 20 hours....! , I did an inspection to see its condition ,as the coasting time was reduced from 2 minutes to 46 seconds , I pulled out of the bearing the oil via a syringe and saw the wear of nylatron using a led light. I put a new one and 3 drops of Schopper oil just to follow Art Dudley's procedure . The results were 57 seconds in the beginning and after 2-3 hours of use it decreased to 46 seconds.
When I checked the syringe where I took the oil I saw at its end a grey material of molecules which was in the oil . When I shacked it ,the material was removed ,as molecules were separated and joined with the oil molecules . After some minutes when I looked in the syringe , the grey materials appeared again. These should be the nylatron molecules from the worn nylatron thrust plate ....
When I used the original thrust plate ,my top plater up and down mechanism was working fine.
The day I changed it with a new one , I cleaned the rubber top discs of the iron platter using isopropyl alcohol . When I installed the iron platter and the top platter , I heard a scratch noise when the top platter was pulled up by the brake platter lift mechanism in order to change a record... I think that isopropyl alcohol might had react with the glue of some of the discs and these are not flat to their perimeter as before cleaning them. Have you any comments for what is happened? Or is the nylatron wear ?
I will check the idler wheel issue you mentioned, if is disengaging properly from the platter rim. Using a stethoscope when I turn the tt off ,I do not hear any noise or a kind of scratch noise due a touch of idler wheel to the platter surface. I have to further check according your advise.
I had recently put a drop of oil to speed change mechanism bushings , but I will check it carefully to see if I did that lubrication to all moving parts of that mechanism.
I think I can remove the idler wheel, put back again the platter etc , put a strobe disc plate to the platter and turn the plater by hand till 33,33 rpm will appear to the strobe. Then to measure the coasting time again and see if there is any difference
Formula One or ultra fast sports cars with fine and specific adjustments and experiments give the ultra good results. So 124 is an old vintage sport car or formula one which needs our passion, hours of experiments and good communication between us in order to perform even better than when it was new.
The last time I changed the new nylatron which used for no more than 20 hours....! , I did an inspection to see its condition ,as the coasting time was reduced from 2 minutes to 46 seconds , I pulled out of the bearing the oil via a syringe and saw the wear of nylatron using a led light. I put a new one and 3 drops of Schopper oil just to follow Art Dudley's procedure . The results were 57 seconds in the beginning and after 2-3 hours of use it decreased to 46 seconds.
When I checked the syringe where I took the oil I saw at its end a grey material of molecules which was in the oil . When I shacked it ,the material was removed ,as molecules were separated and joined with the oil molecules . After some minutes when I looked in the syringe , the grey materials appeared again. These should be the nylatron molecules from the worn nylatron thrust plate ....
When I used the original thrust plate ,my top plater up and down mechanism was working fine.
The day I changed it with a new one , I cleaned the rubber top discs of the iron platter using isopropyl alcohol . When I installed the iron platter and the top platter , I heard a scratch noise when the top platter was pulled up by the brake platter lift mechanism in order to change a record... I think that isopropyl alcohol might had react with the glue of some of the discs and these are not flat to their perimeter as before cleaning them. Have you any comments for what is happened? Or is the nylatron wear ?
I will check the idler wheel issue you mentioned, if is disengaging properly from the platter rim. Using a stethoscope when I turn the tt off ,I do not hear any noise or a kind of scratch noise due a touch of idler wheel to the platter surface. I have to further check according your advise.
I had recently put a drop of oil to speed change mechanism bushings , but I will check it carefully to see if I did that lubrication to all moving parts of that mechanism.
I think I can remove the idler wheel, put back again the platter etc , put a strobe disc plate to the platter and turn the plater by hand till 33,33 rpm will appear to the strobe. Then to measure the coasting time again and see if there is any difference
Formula One or ultra fast sports cars with fine and specific adjustments and experiments give the ultra good results. So 124 is an old vintage sport car or formula one which needs our passion, hours of experiments and good communication between us in order to perform even better than when it was new.
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