I meant just replacing the AC motor with the DC motor, but still use the pulley, belt and step pulley the same way as the E50 motor.
On the question of belts and the issue of the rubber belts leaving residue on the pulleys, has anyone thought of making or having made a belt made of silicone or Mylar or urethane? The original belt on the Kenwood PC400 of similar drive construction as the Thorens, used a silicone belt. It is quiet and does not leave any residue. It runs very quietly as well.
Belt noise 50Hz /60Hz motor pulley
Beltnoise with the Schopper belt measurements show there is lesser noise with the 60 Hz pulley ( turntable running on 120Volt 60Hz ) . Clearly audible .
Belt tension 50 Hz pulley 475 gr.
Noise spectrum
Belt tension 60 Hz pulley 375 gr.
Noise spectrum 60Hz
Beltnoise with the Schopper belt measurements show there is lesser noise with the 60 Hz pulley ( turntable running on 120Volt 60Hz ) . Clearly audible .
Belt tension 50 Hz pulley 475 gr.
Noise spectrum
Belt tension 60 Hz pulley 375 gr.
Noise spectrum 60Hz
Agreed, I got as far as buying a set of replacement motor bushes from eBay (Italy I think) but never used them as it was pretty obvious they were not sintered. That was a risk I wasn't prepared to take. Thankfully my motor is in very decent condition, there is not a hint of wear on the motor shaft and it feels very secure on it's original bushings. I went through the whole process of drilling out the rivets, baking the bushings, replacing the felts and the whole thing is well lubricated with Schopper's oil. I vacuum-loaded the bushings with oil so they are well saturated with the stuff and lots more is available via the fresh felts. I'm confident this is now a good motor rebuild.
Here's a pic from the first time I rebuilt it, I've since redone it and got the bushings a lot cleaner and it now has fresh white felts rather than the pictured originals.
As to the start slightly fast thing many of us are reporting with Schopper rebuilt decks or decks like mine rebuilt using their oil the best explanation I've heard to date is that as the motor heats up the operating resistance of the motor coils drops very slightly causing a slight reduction in current. This makes sense to me assuming the Schopper oil is a little lighter and freer running than that many use. It seems to be the folk using this or very similar oil that have very long spin-down times (40-50 sec). Maybe a heavier oil negates this behaviour as it becomes more free as it warms up, i.e. acts as a slight brake on a cold deck?
I'll be very interested in your findings. I'm convinced that with my own deck (new step-pulley bushings, perfect condition step pulley (in fact a choice of several) that the noise is down to belt shed as cleaning the belt and running surfaces of the pulleys restores silent running. I'm beginning to form a crackpot theory as to the belt shed actually being a factor of too tight a belt, i.e. I suspect it may be an artefact of a belt under too much stress, too much stretch. I am absolutely convinced the vast majority of currently available belts are incompatible with the 50Hz pulley, they are just way too tight.
I received two new belts from Turntable Basics, both of which I've tried before. The first is their FM 13.5, the second the FM 13.9. I've always had good results with the 13.5, it's been my best belt so far, but does shed after a while. The 13.9 is about the max that has sufficient tension to stay on and start the deck, it has potential, but Turntable Basics quality is not perfect and my first 13.9 had a pretty obvious twist so flapped a little when running. The one that arrived yesterday, whilst not perfect seems a lot more straight so I'll give that a go next time I need to go in and clean the pulleys. I'm currently running the new FM 13.5 and the deck is running beautifully quietly, but I bet I get some belt-shed in time. This time I'm not going to put isopropyl anywhere near the belt just in case my cleaning routine has been a factor in the belts shedding rubber.
Anyway, here's a pic of my 124:
Complete bar finding the perfect belt!
Regarding the belt, I may have a slightly different take on them. I think that what I am using is the original that came with my Mark 1, td 124. because I am slightly lazy and forgetful I often leave the turntable on (by accident rather than by design!). I do not know how many hours it has run ( I have had it for about five years) but it was certainly the case in the beginning that the belt was shedding. But I have noticed now that it has stopped doing that and to be quite honest my turntable is now behaving very well and sounding absolutely excellent (which may of course have something to do with the fact that I have also put a Schopper heavy platter, one of Audiosilente's new idler wheels, and a gunmetal mat on the unit).
But the belt has now stopped shedding and the turntable sounds absolutely wonderful and is totally stable (though it does take a long time for it to warm up if started up from cold).
But the belt has now stopped shedding and the turntable sounds absolutely wonderful and is totally stable (though it does take a long time for it to warm up if started up from cold).
Thats also my experience with the shedding provided that the motor pulley and steppulley are polished.
We would have to find someone capable of making these belts, more properly a range of them; there should be specific versions for 50Hz and 60Hz.. I'd certainly be willing to purchase a number of them early on for evaluation and to help defray the costs.
I would think that the original belts were made of a purer rubber, i.e. less silicones/plastics in the mix and that they were less noisy because of this. [But I may well be totally 'up the wrong path' on this]. It would be a good idea to get an unusable/broken original belt and let an expert have a look to determine what was used. [I know that the belts obtainable from Thorens in the early 80s were definitely a different rubber to the original factory belt....they were also tighter and harder/denser material].
Maybe SY who is I believe a plastics scientist will be willing and able to give an informed opinion prior to anyone attempting to have a belt specially made.
Maybe SY who is I believe a plastics scientist will be willing and able to give an informed opinion prior to anyone attempting to have a belt specially made.
I've just fitted the long FM 13.9 belt as I'm curious to try and prove/disprove my theory that belts that shed rubber may be doing so due to being over-stretched and maybe very slightly fracturing due to the strain. I suspect the 13.9 is about as far as one can practically go without the belt slipping, it is a pretty loose fit. It's fine right now and starts the deck perfectly normally and is running very quietly, but if it stretches much I guess it may have some issues down the road.
I'm pretty much convinced that the loosest belt that works is what one wants as it won't be dragging the motor over towards the step pulley or making it rub harder on one side of the motor bushings (same logic applies to the step-pulley bushings). Using the compliant Hanze motor springs this is actually pretty obvious compared with say the Schopper belt which pulls the whole motor over a bit.
I'm pretty much convinced that the loosest belt that works is what one wants as it won't be dragging the motor over towards the step pulley or making it rub harder on one side of the motor bushings (same logic applies to the step-pulley bushings). Using the compliant Hanze motor springs this is actually pretty obvious compared with say the Schopper belt which pulls the whole motor over a bit.
My experience is that belts that shed do so regardless of the tension on them. The Thakker was terrible in this regard but softer and more pliant than the Schopper belt I used until early this week.
It's a good idea.. Unfortunately all of my small collection of OEM belts are in good condition so I would be hesitant to send one off.
I just ordered one from Technical and General from the UK, I have an original on mine and is quiet but decided to purchase another spare. They told me that the belt I ordered is current supply by the present Thorens company, who would have the genuine moulding tools and material specification. In other forums I subscribe to users have had success with this one so will wait and see, as I said mine is quiet so no need to fidget but will purchase it as a backup.
Since the current Thorens company actually has literally nothing to do with the historical Thorens other than name (and possibly some documentation that went with the sale) I am not sure why the current belt would be any better than anyone else's modern belt. I would imagine Thorens purchased the original from a 3rd party supplier to a specific and now probably lost specification back in the day. There are two belt part numbers referenced in my service information, and there seems to be anecdotal evidence that the same belt should not be employed on 50Hz/60Hz tables.
I'll keep my fingers crossed and hope you get a good belt. Can you measure the thickness, state subjective pliability, and measure length when you get it? I've posted details on the OEM belt earlier in the thread.
I'll go ahead and get a couple of the Thorens belts myself to evaluate.
I'll keep my fingers crossed and hope you get a good belt. Can you measure the thickness, state subjective pliability, and measure length when you get it? I've posted details on the OEM belt earlier in the thread.
I'll go ahead and get a couple of the Thorens belts myself to evaluate.
Will do, might be a while yet as I do not have a caliper to measure the thickness in my apt, perhaps will take to HomeDepot and just use a measuring tool there, hopefully not behind glass...LOL! While I wait for the belt there is this old thread that I remember, suspect you may have taken part, scroll down you will see discussions of dimensions.
Best Belt Supplier For Td-124 - Vinyl Engine
Nick L.
Calipers are available for very little from Harbor Freight and others, and seem to be relatively accurate. I have an originally expensive Japanese Mitutoyo, and an inexpensive one made in China, and while the Mitutoyo is nicely crafted, the Chinese one seems just as accurate if not quite as refined in use, it was under $10.00 as opposed to about 10X that for Mitutoyo when it was new.
It'll come in handy for other projects I suspect. I use mine regularly. (Also have dial indicators which I use less often but also surprisingly not expensive)
It'll come in handy for other projects I suspect. I use mine regularly. (Also have dial indicators which I use less often but also surprisingly not expensive)
I have asked Martina about the TD124 motor. Usually Martina knows too much about such things. All she thinks is a general design from a big Swiss company. Generic types are used in heaters costing $20 total to this day. Whilst they are two pole the technical problems of making them is not greatly different. The Thorens motor I always though was 70% of what it should have been. TD150 also. The Lenco is 150% of what one would imagine. Look carefully at the Lenco, a work of art. The Garrard just about is the better type. Of all the places to save money Thorens choose the motor. I have a feeling the motor already existed and was very close to what they wanted. I have to say it looks so much like a Garrard 301 motor as to make me think the TD124 designers looked to that. As far as I know there is a two year time difference 301 to 124. Thorens probably thought the 301 had too much rumble. My guess is they thought the rumble was due to coupling. That being so the motor could be reduced in cost as the money would go into the decoupling. The Garrard 501 which is Martina's baby is - 79 dB. One thing we found is rumble is not a vibrato effect that enhances music. The 501 has lower rumble than most turntables including DD and belt. The motor is about 400% of what is needed. The verve of the 501 is what it has above the TD124/301/Lenco, the initial doubt was rumble was that verve. The motor was my design.
I like the JVC DD. In some ways the L5-E betters the SP10. The SP10 can slow on transients ( Try Peter Gabriel So ). I tried to write about that on a thread as I think I have a cure. I was told I was lacking in technical ability and should go study and perhaps learn maths. I suggested to use the very small pcb track length ( power amp to motor ) to measure the current waveforms in the motor. By playing music see what happens. Then by adding let say an oil bath we can fool the servo's into working better? It's an unusual approach, that doesn't make it wrong. The advantage is the track exists so we are nor changing the reality of the situation. An op amp might be needed to get a big enough spectrum to analyse. I would exspect to see a 5.5 Hz distorted sine wave regardless of whatever servo's used. Some were saying pure DC. I think they misunderstand the final process. 3 phases helps. What I suppose is the distortion in the wave just as the TD124 is related to vibration. The TD124 looks like - 50 dB in the current waveform. Synchronous types about - 25 dB. One thing most peopel don't know is synchronous have almost the same distortion regardless on sine , triangle and square waves ( DC? ). The motor is almost a perfect filter. It is debateable if sine helps. I think it just about does. The TD 124 throws away any chance of better feeding the motor with a low distortion wave . Perhaps a big synchronous could work like the Crouzet Avid use. It is about 300 RPM at 60 Hz. Like stepper motors ( mostly the same thing ) they have an upper limit of working which realates to the filter effect. My guess would be 400 RPM @ 80 Hz. That would need a pully 3 times larger. That kills it I think. There might be a big 600 RPM synchronous that could be asked to do 1300 RPM. Just about possible is to use 78 as 33 1/3 at circa 550 RPM @ 110 Hz ( 300 RPM / 60 Hz type ).
I like the JVC DD. In some ways the L5-E betters the SP10. The SP10 can slow on transients ( Try Peter Gabriel So ). I tried to write about that on a thread as I think I have a cure. I was told I was lacking in technical ability and should go study and perhaps learn maths. I suggested to use the very small pcb track length ( power amp to motor ) to measure the current waveforms in the motor. By playing music see what happens. Then by adding let say an oil bath we can fool the servo's into working better? It's an unusual approach, that doesn't make it wrong. The advantage is the track exists so we are nor changing the reality of the situation. An op amp might be needed to get a big enough spectrum to analyse. I would exspect to see a 5.5 Hz distorted sine wave regardless of whatever servo's used. Some were saying pure DC. I think they misunderstand the final process. 3 phases helps. What I suppose is the distortion in the wave just as the TD124 is related to vibration. The TD124 looks like - 50 dB in the current waveform. Synchronous types about - 25 dB. One thing most peopel don't know is synchronous have almost the same distortion regardless on sine , triangle and square waves ( DC? ). The motor is almost a perfect filter. It is debateable if sine helps. I think it just about does. The TD 124 throws away any chance of better feeding the motor with a low distortion wave . Perhaps a big synchronous could work like the Crouzet Avid use. It is about 300 RPM at 60 Hz. Like stepper motors ( mostly the same thing ) they have an upper limit of working which realates to the filter effect. My guess would be 400 RPM @ 80 Hz. That would need a pully 3 times larger. That kills it I think. There might be a big 600 RPM synchronous that could be asked to do 1300 RPM. Just about possible is to use 78 as 33 1/3 at circa 550 RPM @ 110 Hz ( 300 RPM / 60 Hz type ).
The thing I would like to work out is what exactly causes the noise? It is clear it takes very little belt shed to make quite a racket. Surprisingly little, barely enough to darken a cotton bud, but why? So what is happening here?
I'm guessing the step pulley rings/resonates and amplifies the issue. I suspect one attribute of a 'good' belt is it will damp/deaden the step pulley well, so belt over-tension may play a huge factor here as well as in dragging the motor sideways into its bushings/rubber mounts etc. It is also pretty clear the thicker the belt cross-section the faster the deck runs, so the more one needs the eddy brake and the higher the potential for noise in the system. I remain pretty convinced that the loosest belt that actually works is the one needed and I suspect such a belt will damp the step pulley better and transmit less noise. I'll be very interested to see if the measurements show any change in the frequency of noise correlating to belt tension.
FWIW I'm having excellent results with the new Turntable Basics FM13.9 so far, the deck is all but silent with my ear against it (this belt would likely be too loose for the 60Hz pulley). I may see if I can get away with an FM14!