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Old 23rd November 2010, 10:07 PM   #131
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It's been almost two days since I relubed the motor and made some minor bearing adjustments. So far after a running time of 20 hrs or so everything seems fine. It came up to speed very quickly this morning, and was exactly on speed within 10 minutes and has not drifted at all in 4 hours.

I will keep an eye on this issue and perhaps add some additional lube to the motor bearings in a week or so. I think I may have failed to sufficiently wet the new felts with lubricant, however this bears monitoring as it is not clear to me how new bearings with sufficient lube in them should have ran nearly dry in a couple of weeks unless the felts actually can wick lubricant out of them.
When motor is really right it will 'lock in' sooner. Although it may take some running in to see this, since it seems that no ones attempts at bearing alignments are as optimal as we would like. When you see the strobe operating within 1 % at a 1/2 dozen rpms on a cold start, and you get a solid lock within a minute or two, then the motor is working well.

That your drive train exhibits no speed drift is a good sign.

The felts should have been soaked in lube prior to assembly. I can think of at least two websites that offer a pictorial on motor assembly. Both of these sites will indicate fully saturated felts. Also, the bushings themselves need to be soaked for a day or more prior to assembly. This need comes about because very few have access to the correct vacuum ovens that are used to impregnate the Oilite bronze properly. Therefore soak in clean lube prior to assembly.

I have doubts that the felts could 'wick' lube out of the bushings. Rather, the bushings must have been dry or nearly dry when assembled. This would have been evident upon dis-assembly after the seizing episodes. If the bushings and shaft were found to be dry at that point, then it is highly likely that they were that dry upon the initial assembly.

Quote:
I removed the Thakker sourced belt this morning, it offends me that I can hear so much mechanical racket from a couple of feet away - the old belt is much quieter, however I do need to investigate whether the new bushings are in some way responsible for this, but observed no real deflection of the motor mounts when I install or remove any of the belts I have on hand, but that doesn't mean it isn't happening. There is no audible difference in performance of the table when playing records between the old and new belts so this belt is definitely usable.
The drive train of the TD124 should be silent when standing near it. Only if you put your ear directly over the the TT, within a few inches, should you hear only the faintest whisper/rustle of idler tire noise. All other members of the drive train should be silent. Rather than blaming the belt, we should examine that the step pulley bushings and shaft have been cleaned and lubed in the same oil as used in the motor. Then there is the idler wheel which also needs maintenance at its axle and bushings. Also, test the idler bushings for excess slop by attempting to tip the idler wheel at it its rim. It should be tight yet spin freely with no rattle. The tire surface itself is of concern. Listen for any audible 'knocking' while the TD124 is in operation. If knocking is evident, suspect a flat spotted idler tire.

Just to reaffirm.......I'm not so sure I would place the blame of a noisy drive train upon a new belt that carries the Thorens logo until all other possibilities have been eliminated as noted above.

Further comments:
If you feel the TT sounds good to your ears presently, and you are noticing the noisy drive train, wait until you get this TD124 fully sorted out. It really is an outstanding record player.

Down the road, try experimenting with different tonearms. The SME 3009 S2 are definitely good quality but there are others to play with.
-Steve
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Old 24th November 2010, 12:53 AM   #132
kevinkr is offline kevinkr  United States
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When motor is really right it will 'lock in' sooner. Although it may take some running in to see this, since it seems that no ones attempts at bearing alignments are as optimal as we would like. When you see the strobe operating within 1 % at a 1/2 dozen rpms on a cold start, and you get a solid lock within a minute or two, then the motor is working well.

That your drive train exhibits no speed drift is a good sign.

The felts should have been soaked in lube prior to assembly. I can think of at least two websites that offer a pictorial on motor assembly. Both of these sites will indicate fully saturated felts. Also, the bushings themselves need to be soaked for a day or more prior to assembly. This need comes about because very few have access to the correct vacuum ovens that are used to impregnate the Oilite bronze properly. Therefore soak in clean lube prior to assembly.

I have doubts that the felts could 'wick' lube out of the bushings. Rather, the bushings must have been dry or nearly dry when assembled. This would have been evident upon dis-assembly after the seizing episodes. If the bushings and shaft were found to be dry at that point, then it is highly likely that they were that dry upon the initial assembly.



The drive train of the TD124 should be silent when standing near it. Only if you put your ear directly over the the TT, within a few inches, should you hear only the faintest whisper/rustle of idler tire noise. All other members of the drive train should be silent. Rather than blaming the belt, we should examine that the step pulley bushings and shaft have been cleaned and lubed in the same oil as used in the motor. Then there is the idler wheel which also needs maintenance at its axle and bushings. Also, test the idler bushings for excess slop by attempting to tip the idler wheel at it its rim. It should be tight yet spin freely with no rattle. The tire surface itself is of concern. Listen for any audible 'knocking' while the TD124 is in operation. If knocking is evident, suspect a flat spotted idler tire.

Just to reaffirm.......I'm not so sure I would place the blame of a noisy drive train upon a new belt that carries the Thorens logo until all other possibilities have been eliminated as noted above.

Further comments:
If you feel the TT sounds good to your ears presently, and you are noticing the noisy drive train, wait until you get this TD124 fully sorted out. It really is an outstanding record player.

Down the road, try experimenting with different tonearms. The SME 3009 S2 are definitely good quality but there are others to play with.
-Steve
Hi Steve,
When I rebuilt the table I checked the condition of all of the components in the drive train. There is a concern with the idler pulley in that I can see a very small ripple in it, however it doesn't generate any noise or knocking, and it is perfectly round. There is no discernible play in the idler or intermediate pulley bearings. The noise has decreased substantially as the table has run today, it is no longer audible more than about six inches from the table with the original belt. Note also that the noise is present whether or not the idler is engaged (with the platter off) - it doesn't seem to add appreciably to the noise level.

I think the Thakker is acceptable from a performance perspective and the fact that is it somewhat less elastic could be pulling the motor out of alignment. A friend who just bought the same bushings commented that he was surprised at how soft they are. I gave him a loaner belt tonight and he will let me know if he hears anything like I am hearing here. His comment was that his table makes about the same level of noise as mine.

I am sure based on your comments that I made a serious mistake in not really drenching the felts in oil. The motor bearings were supposedly fully oil impregnated and ready to go when I purchased them, and were packed in oil. I did apply additional oil after assembly, and again on Sunday when I reported I was having an issue. I think I will "top off" again in a couple of days if I note any increase in drag. This morning it felt the same as it did after several hours of running the other day, but hard to judge.

I think even at start up the speed is well within 1% and had understood it took about 10 minutes to lock in, but have not timed it, definitely more than 5 minutes though. I would expect that the motor is not fully broken in at this point based on what you are saying.

I have a 3012 which will be the first arm I experiment with, eventually as my machining skills get better I'd like to clone a 12" Sheu arm, a project for the distant future I think.

Overall I am very pleased with the turntable, I take these issues to be part of the learning curve, and I also bear in mind that this turntable has not run in 4 decades so some minor issues are to be expected.

I guess the one thing I am wondering about is how much better off I would have been using all Swiss sourced parts in my rehab.. It was just easier to point and click on eBay, the press on these guys is all favorable, and I hadn't run into you yet - I'd have sourced some things differently in retrospect.

I've had the opportunity to listen to several homebrew and aftermarket mats and am definitely sticking with original mat - this is the first time I have ever preferred an OEM mat, but changing it messes in subtle ways with the qualities of this table that attracted me to it in the first place.

Honestly I can't imagine I really need anything else going forward, other than to satisfy curiosity, (which I have) and there are certainly decent upgrades like the Schopper platter, better plinths, arms and cartridges to take it further..
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Old 24th November 2010, 02:37 PM   #133
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Talking Another Update..

Checked early this morning to determine how quickly the turntable starts from cold, again it was up to playing speed in about 1/3rd of a platter revolution which is good news..

For good measure I added some additional oil to the top and bottom motor bearings as I believe Steve is correct and I simply did not use enough oil on the felts. I have seen all of the motor rebuild sites, and referred to them as I rebuilt the motor - I guess I scrimped a bit on the oil because of the mess the stuff makes.. It's very important to use sufficient oil, and even with pre-oiled bearings I would now recommend following at least part of the recommendations listed here: ƒg[ƒŒƒ“ƒX THORENS model TD 124

It still takes about 10 minutes for my table to warm to the point where it attains set speed, but it is very cool down here in my listening room, and it is also pretty clear from the issues I've had that the new bearings are not broken in yet.. (Note that it is immediately usable - mine is running around 1% slow initially.)

I am coming to understand why many motor rebuilders run these motors continuously for a week, and then tear down, clean and relubricate them before re-installation in the table. I was anxious to get the table going and only ran in the motor for a couple of hours before installing it - just long enough so that it was no longer running excessively warm. I also haven't fully disassembled the motor and cleaned the bearings and shaft as I probably should - my reasoning was that the factory making these motors certainly didn't do this so why should I? Well once I achieve a couple of hundred hours of run time I now think I will pull it apart and clean it.
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Old 26th November 2010, 04:26 AM   #134
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Interesting Kevin. Reminds me of another precision device, 35MM movie cameras. After a rebuild they had to be run in for many, many hours. Getting the gears to mesh smoothly and quietly was the goal.

Don't know if the modern cameras need this, but the old ones (50s, 60s) did.
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Old 27th November 2010, 11:47 PM   #135
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Interesting Kevin. Reminds me of another precision device, 35MM movie cameras. After a rebuild they had to be run in for many, many hours. Getting the gears to mesh smoothly and quietly was the goal.

Don't know if the modern cameras need this, but the old ones (50s, 60s) did.
It's still running in.. The good news is that I have a friend with a close serial # MKII which is behaving quite similarly even down to the noise issues with different belts, unfortunately like mine it also has the geltec bushings.

I guess have no idea where my belt came from because according to every reputable source I have contacted the belt has always been 0.9mm thick, but mine is definitely 0.58mm thick and runs a lot quieter with the geltec bushings installed than my new CB965 although as I have indicated there is no audible consequence to performance when playing records - the machine is just a bit noisier.

I should be able to listen to the drive train noise in an unrestored, but running low serial # MKI in the near future. The owner says it is very quiet. (It will be restored prior to actual use.)
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Old 29th November 2010, 10:35 PM   #136
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Probably flogged this subject to death, but I took the table apart again today and looked at everything again in excruciating detail.

The motor now comes up to speed very quickly, and after an hour's operation is barely warm to the touch. It appears that the motor is now largely broken in.

I have examined the motor bushing issue and it appears to me that all three deflect equally and quite minimally and deflection is a function of the length and elasticity of the belt. There is no evidence that the motor pulley running surfaces aren't perfectly parallel to the intermediate pulley running surfaces.

I also played with pulley alignment and even went so far as to deliberately slightly mis-align (angle - the other more appropriate word is censured by the forum software) the motor by hand relative to the intermediate pulley, and discovered this has an almost indiscernible effect on the noise I have been complaining about. Changing the motor pulley height also has minimal effect as long as any part of the belt is still riding on the crown of the intermediate pulley. I like mine well centered, and there it stays.

The intermediate pulley bearing and shaft are free of any evidence of wear, and my dial indicator was not able to detect any significant eccentricity in the belt running surface or the pulley. (A couple of thousands or less - better than my dial indicator) This tells me there is nothing wrong with the pulley other than what it is made of - it is really resonant. This component was significantly redesigned between the MKI and the MKII to improve some other aspect of its performance, but I wonder if the bearing assembly as originally installed in the pulley provided some damping...

Belt elasticity, thickness and tension all seem to have a very large effect on the noise levels generated followed closely by surface imperfections on the motor and intermediate pulleys. I had previously checked the intermediate pulley for surface roughness and it appears reasonably if not perfectly smooth. The crown of the 60Hz pulley on the motor was another matter - I'm not sure what the issue was but I lightly burnished the surface and was able to significantly reduce excitation of the belt by surface roughness on the motor pulley - this had a small but noticeable effect on noise, however it also seems to have resulted in a significant reduction of friction. (This could even be old belt residue..) All of this points to the need to keep things scrupulously clean. I also noted that a wet belt (alcohol - I don't care about the longevity of this belt..) runs dead silent - so I am thinking that some talc might actually be in order here.

I have, umm.... ordered more belts to try.. I am currently running the Thakker Thorens CB965 and this is definitely the second quietest of the three belts I currently own. The third belt by turntablebasics is a good deal noisier. I want to see if the Thakker belt will quiet down with more running time and/or talc as I need a long term solution - the original belt serves as a reference.

I have decided barring some unforeseen disaster I am going to move on to plinth and other issues as it is clear I am wasting my time. Nothing is audible at the cartridge, the table is extremely quiet playing anything including the lead out grooves at the end of a side. The main bearing is excellent. I will soon get to hear the mechanical noise levels of an unrestored MKI (allegedly very quiet) and a restored MKII (the owner reports having exactly the same noise issues) and that will be more revealing I think. FWIW I am not expecting any surprises..

The areas I do think worth most immediately addressing are a better plinth and that zamac platter - I am pretty sure that its colorations are audible as a bit of extra zing in the upper midrange. I'm going to try (reversibly) damping the platter as some changes I have tried as noted previously have not really been an improvement - they might have addressed an issue, but the medicine was far worse than the disease..

Anyway for all of the commentary I'm pretty happy with what I am hearing, and there is potential to go a lot further as resources permit.
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Old 30th November 2010, 05:35 PM   #137
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Default Belt Noise

This morning I picked up some talcum powder and carefully removed the CB965 belt and applied it after listening to the drive train for a quick baseline. The belt noise is substantially reduced by this treatment which I guess is why Thorens recommended it in the first place.

It seems that the tighter/stiffer the belt the more the belt chatters as it goes around the circumference of the two pulleys. In the MKII the intermediate pulley is not well damped and rings badly due to this excitation. The talc seems to provide some lubrication between the belt and pulleys which allows the belt to run without chattering.

It's a good idea before reinstalling the "dusted" belt to make sure that there is as little loose talc as possible so it doesn't end up all over the inside of the turntable and potentially in the motor or main bearings.

I am not sure how long term this fix is, and I expect that at best it means periodic belt maintenance may be required.
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Old 1st December 2010, 03:33 PM   #138
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Default Belt Noise and Ongoing Tweaks

Ran the table continuously for more than 8hrs yesterday and am happy to report that noise levels did not increase and may in fact have decreased very slightly over the course of the day.

Design of a custom plinth will start soon.

Will attempt to minimally damp the platter from the bottom side if at all possible. (Depends on material thickness and clearance to components in the drive train.)

There is something organic to the sound that is hard to describe. I have never heard records sound better (prat, detail, imaging, sound stage, presence, noise floor, tonal balance, you-are-there presentation) in my current system or any prior system I have owned. Getting this vinyl playback thing right is not nearly as trivial as I thought, and I never really thought it was that trivial. (i.e. known good hardware automatically results in good sound if carefully set up. I now realize there is something more to it.) Having this finicky turntable has forced me to really focus on the details, and somehow everything on the table along with my arm and cartridge works synergistically to retrieve the maximum amount of musical "enjoyment" from the disk - not to mention a whole lot of things I have never even heard before. In some extreme instances it is almost like hearing another recording altogether, and it's FUN..
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Old 2nd December 2010, 07:31 AM   #139
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Your daily/semi-daily notes indicate good progress. It does take some time and tinkering before one gets really comfy with how well the project went on one of these models. Particularly on the first one. It is not an overly complex drive train, but does seem to have its fussy adjustments.

re: belts. They do stretch over time. The ones we think are too tight initially become less so in a month or two. Even so, it is disconcerting to find that 3 out of 3 belt suppliers offer belts for this TT with significant dimensional differences between them.

With that in mind, I'd have to admit that the good old days haven't really returned. For those of us still spinning vinyl in the 21st century, some amount of ingenuity is required to keep some part of the thing working.

But maybe that is part of the fun.

-Steve
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Old 2nd December 2010, 02:49 PM   #140
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It continues to work well, so I am going to focus on running it as much as possible. The talc really seems to have done the trick as the table remains relatively and consistently quiet. Speed consistency is very good with no tweaks being required to the setting.

I will probably need to adjust the eddy current brake at some point as the restored turntable apparently has less friction induced losses than when built. It now runs a bit faster at any given setting of the eddy current brake and so is no longer centered at +/-3% when running at a nominal 33.33rpm.. The fact that the motor runs only warm to the touch after hours of use might tend to confirm this..

The belt plot thickens as yesterday I received a set of belts from a seller on eBay represented to be for the TD-124, right length, 0.025" thick, but only 0.125" wide.. They came with a nice note about how much money I had saved, unfortunately the fact that they are incorrectly designed for the table means I can't use them.. No savings in that, hopefully I can return them soon. Sadly they appear to be of good quality too...

All in all though I would say more than worth the trouble, and based on the ones literally coming out of the wood work around here I will probably be helping some friends to get their's going as well. It is a truly amazing feat for a designed engineered at the dawn of stereo to remain more than just relevant 53 yrs after its original commercial release..


Edit: Just heard from the belt seller, and he is going to ship me a pair of the correct ones. I'll report back on how they are..
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