Their are two main types of resonance. The additive and subtractive, both are not really what one wants. Rubber subtracts. It's like a reactive electronic circuit. OSB has many followers as it has both the qulities of ply and some of MDF. To have resonance one makes all particles the same ( think many ball bearings in a frame ). To avoid it different is best. Cork in neoprene for mats seems to be an ideal compromise. OSB and MDF with perhaps animal glues could be good. Mass also is important. Too much can be a problem. 50 tons might work. I doubt 200 lbs is helpful. 20 to 60 lbs inc TD124 is about right. I use squash balls to suspend the motor unit and keep that mass as low as I can whilst being ridged. 25mm MDF and 6 mm ply bonded is OK for that. If you want concrete put it below the squash balls. BTW, they do go flat, they still work. Just shim them. In time they settle.
Update: 12/7/2017
OK, today I tore the table down and re-lubed the motor bearings, idler wheel and stepped speed pulley with 3-in-1 electric motor oil.
Here are the results:
The table spins up to speed just fine. That problem is solved.
However at line voltage (120VAC) with the eddie current magnet adjusted as close as it can be the table runs way fast out of adjustment range.
I tried adjusting the voltage using my cool little switched transformer. First I tried 118VAC. Slower, but still fast out of adjustment range.
I kept stepping the voltage down to 104VAC. Each lower step led to slower speed, but even at 104VAC, the table is still a bit too fast.
Below 104VAC the strobe light would not light.
My suspicion is that my eddie current magnet is weak. Is there a way to re-magnatize it. Does anyone offer this service?
Other potential solutions:
Eddie current solution, Place adhesive backed magnetic tape on the vanes inside the stepped pulley.
Eddie current solution, Place neodymium magnets on the existing magnet to boost it's strength.
Voltage solution, I looked at the circuit that is used to switch the input voltage from 220 to 110. There is a rather long in the tooth 3.3K 1/2 watt resistor in there. I measured it in circuit at 3.5K. I wonder if I played around with the value of this resistor to bring the speed down. Perhaps start out with a 4K & see what I get.
That resistor is actually 33K (orange orange orange plus gold [5%] or silver [10%] tolerance band if present) and is the current limiting resistor for the neon lamp.
It sounds like the magnet is a bit weak, but how close is it to the stepped pulley? As long as it does not hit the pulley you can place as close as necessary and should be OK. (Mine is about .15 inches from the pulley currently running on 117V 60Hz sine wave source)
Possibly you could remag it, but I currently know of no one who does this, seems there might be a market for a replacement magnet.
I am not sure the eddy current brake would work effectively with the magnets on the inside.
I posted the schematics for the motor and lamp connections in this thread long ago.
It sounds like the magnet is a bit weak, but how close is it to the stepped pulley? As long as it does not hit the pulley you can place as close as necessary and should be OK. (Mine is about .15 inches from the pulley currently running on 117V 60Hz sine wave source)
Possibly you could remag it, but I currently know of no one who does this, seems there might be a market for a replacement magnet.
I am not sure the eddy current brake would work effectively with the magnets on the inside.
I posted the schematics for the motor and lamp connections in this thread long ago.
Are you also in possession of a rpm meter so you can measure the speed of the motor. I can measure your magnet and check it .
Thanks you are correct about the resistor. My short term memory is pretty poor. It is an Orange orange orange silver.
My magnet is much closer than 0.150 In. I gapped it by placing a home depot receipt between the magnet and the stepped pulley. Loosened the magnet and scooted it up against the receipt then locked it down again. I estimate the gap at less than 0.005 in.
I've been researching the magnet problem all day so far. Here is what I have and haven't come with.
I tested the strength of my magnet by lifting a transformer and clipping weight to the wires until it broke free of the magnet. The total that was held was then weighed on a digital postal scale. It looks like my magnet lifts about 3 pounds +/- 3 oz.
I looked up sources for replacement magnets and found nothing that would both fit and listed the lifting strength.
I looked for instructions on how to re-magnitize my magnet and am not yet satisfied I know the best way to do it. The easiest to find sites are:
A science site
How to Recharge a Horseshoe Magnet | Sciencing
that describes how to re-magnitize a horseshoe magnet using something called an "Electromagnetic Charger". They also say one can DIY one, but give no instructions. There are no pics on this site showing either the equipment used or the process. When I search for the electromagnetic charger I get all kinds of wireless battery charging devices. I don't think that is what they are talking about.
And a comercial site
Why are Magnets Shaped like Horseshoes?
That links to a youtube video and shoes how to demagnetize and remagnetize a magnet using Neodymium magnets.
I also found a forum (I didn't save it) where someone suggested remagnetizing using electromagnetism will result in a stronger magnet than the use of Neodymium magnets.
I also found a good source for Neodymium magnets.
SuperMagnetMan - Your Experienced Magnet Partner
The supermagnetman man also has lots of information and videos, but does not cover remagnitizing specifically. I tried contacting them, but no one was at home.
So here are my options:
Learn how to magnetize my magnet using the electromagnetic approach. (Preferred)
Buy some large 1/2 inch diameter neodynium cylinders and attempt to magnetize my magnet using them.
Buy some small neodynium discs, Grind the ends of my horseshoe magnet flat and epoxy them on. One neodymium disc .5 inches in diameter X .25 inches thick yealds 4.258 pounds of pull. 2 of them would give me close to twice that.
It would be nice to know the pulling strength of a brand new TD-124 eddy current magnet.
I tested the strength of my magnet by lifting a transformer and clipping weight to the wires until it broke free of the magnet. The total that was held was then weighed on a digital postal scale. It looks like my magnet lifts about 3 pounds +/- 3 oz.
I looked up sources for replacement magnets and found nothing that would both fit and listed the lifting strength.
I looked for instructions on how to re-magnitize my magnet and am not yet satisfied I know the best way to do it. The easiest to find sites are:
A science site
How to Recharge a Horseshoe Magnet | Sciencing
that describes how to re-magnitize a horseshoe magnet using something called an "Electromagnetic Charger". They also say one can DIY one, but give no instructions. There are no pics on this site showing either the equipment used or the process. When I search for the electromagnetic charger I get all kinds of wireless battery charging devices. I don't think that is what they are talking about.
And a comercial site
Why are Magnets Shaped like Horseshoes?
That links to a youtube video and shoes how to demagnetize and remagnetize a magnet using Neodymium magnets.
I also found a forum (I didn't save it) where someone suggested remagnetizing using electromagnetism will result in a stronger magnet than the use of Neodymium magnets.
I also found a good source for Neodymium magnets.
SuperMagnetMan - Your Experienced Magnet Partner
The supermagnetman man also has lots of information and videos, but does not cover remagnitizing specifically. I tried contacting them, but no one was at home.
So here are my options:
Learn how to magnetize my magnet using the electromagnetic approach. (Preferred)
Buy some large 1/2 inch diameter neodynium cylinders and attempt to magnetize my magnet using them.
Buy some small neodynium discs, Grind the ends of my horseshoe magnet flat and epoxy them on. One neodymium disc .5 inches in diameter X .25 inches thick yealds 4.258 pounds of pull. 2 of them would give me close to twice that.
It would be nice to know the pulling strength of a brand new TD-124 eddy current magnet.
If it is lifting 3 lbs I would say there is nothing wrong with the magnet, and you are having an issue common to MKIIs.
Are you using the correct side of the motor pulley? The larger diameter section of the pulley is for 50Hz.
The other thing is the belt, most are too thick and result in the table running a bit fast. Hanze HiFi has good belts for these tables.
Finally you might want to flush the main bearing and refill if there is any possibility of the previous oil mixing with the 20wt oil.
Are you using the correct side of the motor pulley? The larger diameter section of the pulley is for 50Hz.
The other thing is the belt, most are too thick and result in the table running a bit fast. Hanze HiFi has good belts for these tables.
Finally you might want to flush the main bearing and refill if there is any possibility of the previous oil mixing with the 20wt oil.
Here are some examples with the measured strenght the one with 100 pulls about 1 kg //2,2 lb.seems your magnet is ok.
Thanks kevenkr solved my problem. Turns out the drive pulley on the motor was flipped to the 50Hz end. I flipped it over to the 60Hz end and it is keeping rock solid proper speed with about 0.100 gap between the magnet and the stepped pulley.
I'm verry pleased with the result and want to thank everyone on this site for their assistance.
Also I'm a little embarrassed I didn't catch this on my own. I pride myself on my mechanical skill. I'm surprised I missed this.
I'm verry pleased with the result and want to thank everyone on this site for their assistance.
Also I'm a little embarrassed I didn't catch this on my own. I pride myself on my mechanical skill. I'm surprised I missed this.
Thanks everyone!
Yesterday evening my wife and I had a nice evening siting by the fire and listening to my vinyl jazz collection using the TD-124. It was most delightful.
The TD-124 replaced a Dennon DP62r. The Dennon was a good table, but a LED went out on it. I downloaded the service manual and when I got a look at what was inside I never felt comfortable with it again. Not that it was poorly made. If fact it is very well made. However, I feel uncomfortable with equipment in my system that I cannot repair. The Dennon has IC's all over the place. If I get a power serge and one of them blows I'll be stuck with a $500.00 door stop.
I am much happier with the Thorens TD-124. There is nothing in it I can't fix.
Yesterday evening my wife and I had a nice evening siting by the fire and listening to my vinyl jazz collection using the TD-124. It was most delightful.
The TD-124 replaced a Dennon DP62r. The Dennon was a good table, but a LED went out on it. I downloaded the service manual and when I got a look at what was inside I never felt comfortable with it again. Not that it was poorly made. If fact it is very well made. However, I feel uncomfortable with equipment in my system that I cannot repair. The Dennon has IC's all over the place. If I get a power serge and one of them blows I'll be stuck with a $500.00 door stop.
I am much happier with the Thorens TD-124. There is nothing in it I can't fix.
There are several sources for these new as well as eBay where they turn up from time to time.
Schopper can provide a new one and sometimes sells off originals on eBay.
Some would argue the table sounds better without it, definitely not the case with the Zamac platter, but with cast iron it may be so. I have not been able to establish definitely whether that is the case, but I use Merrill-Scilia mat on the MKII, and a Gem Dandy (also Merrill) on the older 124. I like the look of the aluminum top platter. There are some modern heavier ones that look interesting in the $500 range. (!)
The table will work without the top platter, I ran one of mine that way as I collected the remaining bits to restore it. Any good cork/rubber mat should be fine as would one of the thicker Herbie's Audio mats.
Schopper can provide a new one and sometimes sells off originals on eBay.
Some would argue the table sounds better without it, definitely not the case with the Zamac platter, but with cast iron it may be so. I have not been able to establish definitely whether that is the case, but I use Merrill-Scilia mat on the MKII, and a Gem Dandy (also Merrill) on the older 124. I like the look of the aluminum top platter. There are some modern heavier ones that look interesting in the $500 range. (!)
The table will work without the top platter, I ran one of mine that way as I collected the remaining bits to restore it. Any good cork/rubber mat should be fine as would one of the thicker Herbie's Audio mats.
Thorens TD-124 Neon bulb?
I have been enjoying my TD-124 a lot lately, but the Neon bulb just burned out. I replaced it with a lower wattage Neon that works, but is not quite bright enough. The original is 1-watt. I have found replacements on ebay for around $40.00 each, but before I order I just wanted to ask if anyone has tried any other kind of bulb or LED in a Thorens TD-124.
I have been enjoying my TD-124 a lot lately, but the Neon bulb just burned out. I replaced it with a lower wattage Neon that works, but is not quite bright enough. The original is 1-watt. I have found replacements on ebay for around $40.00 each, but before I order I just wanted to ask if anyone has tried any other kind of bulb or LED in a Thorens TD-124.
I purchased all of my replacements on eBay. I figure they last a long time so $30 - 40 is not terrible, sometimes there are better deals.
Make sure that the 33K resistor on the back of the voltage change board is OK. (It should measure within 10% of nominal value, if it is outside this range it should be replaced)
Make sure that the 33K resistor on the back of the voltage change board is OK. (It should measure within 10% of nominal value, if it is outside this range it should be replaced)
