The magnet should offer a pre load and it is a valuable sound quality issue to have some. Verdier was quick to point out eddy currrent braking has a different graph to oil in bearings ( SAE 30 no additives if needing some drag ). Verdier said for a given speed the magnetic " drag " could be considered the same as that of oil in effect.
I think I have a hard time understanding how any increased load, whether eddy brake, stylus, or whatever, would not be seen by slower strobe movement? Don't misunderstand. I am not saying you are wrong, I am saying I am just having a difficult time understanding this???
Again, I am not doubting anyone here, just trying to understand. If I leave the magnet in the same position but change oil from 20W to 30W , wouldn't I have to now use the fine speed adjusting knob to lock the speed again😕
the speed does not "lock". It is not a synchronous motor.
But even a synchronous motor does not lock the TT dynamically.
There is some dynamic slip as the motor load is varied.
But even a synchronous motor does not lock the TT dynamically.
There is some dynamic slip as the motor load is varied.
Not sure about the Verdier comments, but the eddy current brake introduces considerably more drag that any changes in lubrication I have tried so far even in the main bearing, the effects in motor bearings and in particular the intermediate pulley bearing seem lessened; but yes I would expect a slight adjustment to the brake setting with a lubricant change.
The above is all based on empirical observation, and I have NOT performed any controlled experiment to verify my impressions of this particular behavior.
I think 30wt in the main bearing is a viable alternative to 20wt particularly bearing in mind that the original oil was somewhere around 22wt. In very cold climates (cold rooms like mine) this can result in longer warm up times.
If you are having the oft discussed overspeed problem one possible solution is to slightly reduce the supply voltage by 5 - 10V with a buck transformer, variac or similar.
The above is all based on empirical observation, and I have NOT performed any controlled experiment to verify my impressions of this particular behavior.
I think 30wt in the main bearing is a viable alternative to 20wt particularly bearing in mind that the original oil was somewhere around 22wt. In very cold climates (cold rooms like mine) this can result in longer warm up times.
If you are having the oft discussed overspeed problem one possible solution is to slightly reduce the supply voltage by 5 - 10V with a buck transformer, variac or similar.
This is correct and changes in load will be reflected directly in speed changes.
Having produced bearings of various running clearances a change from SAE 20 to 30 might be a big change. Why the TD124 owner will not see this is the bearing has a critically large clearance. When people speak of microns they do not mean clearance. They mean bearing finish. Mostly bearing finish is unimportant, whilst the bearing being truely round ( which can not be seen ) is critical. Micron finish is a visual thing and is cheap enough to do. The running clearance is larger than a cigarette paper. When dry ( truely dry ) there is enough slop to seem broken for want of a better word. In goes the oil and it will seem ridged.
I had a bearing made to half the usual clearance. It took 10 hours to come to speed on SAE20. It would still have seemed broken without the oil. The SAE 30 in a TD124 might be enough to win back something.
The belt of a belt drive turntable is also a reactive device when saying synchronous or otherwise. My text book says " at small load a hysterisis motor can be considered synchronous ". The hysterisis loop is a big advantage. As the motor is loaded vibration does not increase dramatically. The speed drops a little and stays reasonably constant. Drag in the book of Verdier could be made 10 times greater than stylus drag. This would allow the turntable to ignore the stylus to a factor proportional to the darg. When a synchronous motor is loaded it will vibrate more than a hysterisis whilst retaining speed up to the critical loading point. At the same loading I would exspect a 2 % difference in speed within posssible usuable ranges when hysterisis and synchronous.
Grease in an early Garrard 301 reduces speed by about 2.5 %.
I think I might have said I was repairing a JVC L5-E DD turntable for my old boss as a TD124/401 type sound in a compact unit. It is with LS3/5A- KANS clones and A&R A60. L5-E is based on JVC TT-71 ( looks like Denon ). I have to say it is a delightful turntable. It looks so cheaply made, it isn't . Even the silly looking arm is ridged and sounds very good. The previous L3-E looks better made ( my friend Colleen has one ). The sound very similar between 3 and 5 E. The L5-E might be slightly better. The L3-E looks better made. There even seems to be a piece of Mu-metal to shield the arm. Some Mu types cost more than silver these days. The sound to my ears betters Technics 1210 and perhaps SP-10. There is no suggestion of dynamic wow which SP10 can sometimes show ( fast bass lines ). Bass is very solid which proves motor rather than patter mass it the key. Midband is very open unlike Sony DD that I have heard. They sound more like low cost CD players. Even the AT-93 look alike stylus seems to work well ( generics seems fine ). I think I might track down a TT-81 if the price it right.
I had a bearing made to half the usual clearance. It took 10 hours to come to speed on SAE20. It would still have seemed broken without the oil. The SAE 30 in a TD124 might be enough to win back something.
The belt of a belt drive turntable is also a reactive device when saying synchronous or otherwise. My text book says " at small load a hysterisis motor can be considered synchronous ". The hysterisis loop is a big advantage. As the motor is loaded vibration does not increase dramatically. The speed drops a little and stays reasonably constant. Drag in the book of Verdier could be made 10 times greater than stylus drag. This would allow the turntable to ignore the stylus to a factor proportional to the darg. When a synchronous motor is loaded it will vibrate more than a hysterisis whilst retaining speed up to the critical loading point. At the same loading I would exspect a 2 % difference in speed within posssible usuable ranges when hysterisis and synchronous.
Grease in an early Garrard 301 reduces speed by about 2.5 %.
I think I might have said I was repairing a JVC L5-E DD turntable for my old boss as a TD124/401 type sound in a compact unit. It is with LS3/5A- KANS clones and A&R A60. L5-E is based on JVC TT-71 ( looks like Denon ). I have to say it is a delightful turntable. It looks so cheaply made, it isn't . Even the silly looking arm is ridged and sounds very good. The previous L3-E looks better made ( my friend Colleen has one ). The sound very similar between 3 and 5 E. The L5-E might be slightly better. The L3-E looks better made. There even seems to be a piece of Mu-metal to shield the arm. Some Mu types cost more than silver these days. The sound to my ears betters Technics 1210 and perhaps SP-10. There is no suggestion of dynamic wow which SP10 can sometimes show ( fast bass lines ). Bass is very solid which proves motor rather than patter mass it the key. Midband is very open unlike Sony DD that I have heard. They sound more like low cost CD players. Even the AT-93 look alike stylus seems to work well ( generics seems fine ). I think I might track down a TT-81 if the price it right.
TD 124
Does anyone have the planes for a TD124 base? also I need the color of the paint number so I can pant it. I know its a off white. I'm getting my 124 next week.
thanks
Does anyone have the planes for a TD124 base? also I need the color of the paint number so I can pant it. I know its a off white. I'm getting my 124 next week.
thanks
Hi theoman. Go to the following URL for the base plans.
http://www.theanalogdept.com/images/spp6_pics/TT manuals/Thorens/TD124 Cut Template_not to scale.pdf
http://www.theanalogdept.com/images/spp6_pics/TT manuals/Thorens/TD124 Cut Template_not to scale.pdf
A late mk 1...some differences..
I had a project turntable come my way recently. Serial No. 57175. A fairly late first version. I documented its restoration at my site. In the process I noticed some differences in its build. I'll show pictures below:
Firstly, it came to me in pieces. Oh what fun, all the fasteners, washers and clips were tossed into the same bag. Actually it wasn't too difficult to sort these out. But I did refer to some photos I have at the site on other restoration projects I have documented.
Above photo: on/off switch.
To me the most apparent difference was this on/off switch. An open design which requires the leads to be soldered to a terminal rather than attached by machine screw. After looking it over I came to appreciate the simplicity of this switch design. The earlier versions are a bit more of a 'pain' to hook up than this one. I like it.
It has the later version stepped pulley bearing housing.
Above photo; looking at the stepped pulley axle mounting and adjusting method. Note also the plastic cup attached. It took me a while to figure that this was a 'drip cup' designed to catch any excess lube seepage.
Above photo: stepped pulley axle housing and bushings seen from above.
Above photo: stepped pulley thrust pad and height adjuster assembly.
I have many other photos of the project at this link:
57175
the motor came to me already having been refurbished. I just disassembled, cleaned, re-lubed, assembled and adjusted to keep it fresh.
This motor comes up to speed right away and runs cooler than most TD124 motors I have seen.
Installing the platter to the bearing.
As noted at the top...this came to me fully disassembled. Meaning that the platter bearing was not assembled to the platter. Given this much info I decided to check the assembled bearing/platter for concentricity between the inner driven rim (where the idler wheel drives) and the axis of rotation (bearing ).
Above photo: checking for runout at the inner driven rim.
At first I saw .005" runout this surface. With some gentle nudges (using a light plastic mallet to shift location of platter relative to the bearing shaft) I was able to get runout to within .001". This is essential because the fit-up between bearing and platter does have some clearances. If you don't take this step of reading runout and adjusting for it...you can have less the ideal wow/flutter.
-Steve
I had a project turntable come my way recently. Serial No. 57175. A fairly late first version. I documented its restoration at my site. In the process I noticed some differences in its build. I'll show pictures below:
Firstly, it came to me in pieces. Oh what fun, all the fasteners, washers and clips were tossed into the same bag. Actually it wasn't too difficult to sort these out. But I did refer to some photos I have at the site on other restoration projects I have documented.
Above photo: on/off switch.
To me the most apparent difference was this on/off switch. An open design which requires the leads to be soldered to a terminal rather than attached by machine screw. After looking it over I came to appreciate the simplicity of this switch design. The earlier versions are a bit more of a 'pain' to hook up than this one. I like it.
It has the later version stepped pulley bearing housing.
Above photo; looking at the stepped pulley axle mounting and adjusting method. Note also the plastic cup attached. It took me a while to figure that this was a 'drip cup' designed to catch any excess lube seepage.
Above photo: stepped pulley axle housing and bushings seen from above.
Above photo: stepped pulley thrust pad and height adjuster assembly.
I have many other photos of the project at this link:
57175
the motor came to me already having been refurbished. I just disassembled, cleaned, re-lubed, assembled and adjusted to keep it fresh.
This motor comes up to speed right away and runs cooler than most TD124 motors I have seen.
Installing the platter to the bearing.
As noted at the top...this came to me fully disassembled. Meaning that the platter bearing was not assembled to the platter. Given this much info I decided to check the assembled bearing/platter for concentricity between the inner driven rim (where the idler wheel drives) and the axis of rotation (bearing ).
Above photo: checking for runout at the inner driven rim.
At first I saw .005" runout this surface. With some gentle nudges (using a light plastic mallet to shift location of platter relative to the bearing shaft) I was able to get runout to within .001". This is essential because the fit-up between bearing and platter does have some clearances. If you don't take this step of reading runout and adjusting for it...you can have less the ideal wow/flutter.
-Steve
My Series 1 (#48755) is like this, too, though I am missing the rather nifty 'oil-collecting washer'.
I have the Schopper non-magnetic platter which appears to have a better fit to the spindle and not to have the need for checking the inner rim runout (but then again, I do not have the fancy gauge that you have so I could be wrong).
I have the Schopper non-magnetic platter which appears to have a better fit to the spindle and not to have the need for checking the inner rim runout (but then again, I do not have the fancy gauge that you have so I could be wrong).
Cool on the Schopper non-mag platter. That is said to be a significant upgrade. I'd love to try one some day but the price of it gets in my way.
re: fancy gage. Standard machinist's tool A Mitutoyo 'finger' indicator with .0005" graduations. It has been a reliable work-horse for me. And also the magnetic stand used to hold it.
I conjecture that Your #48755 and this 57175 carry parts that were also used on the MK II. But I haven't had a MK II to work on yet.
-Steve
Steve the plastic cup is not original own mod I think from previous owner.The later bearing screws had a rubber ring on it , black one not but with some gastape you can fix it.
These open switches are in later versions from the MK1 and in all MK2 TD124.
I can confirm some things as I have a 47xxx MKI and a very late MKII, and with a few minor exceptions they are nearly identical. Unfortunately my MKI came missing parts and some of the parts to fix it came from a much older basket case unit, they fit and worked without issue.
The motors have different windings, and frankly the older unit's motor is a better performer in terms of warm up time.
The MKII as far as I can recollect does not use a thrust pad in the intermediate pulley bearing assembly. Since I continue to have problems with it I will check one of these days. Neither came through with the plastic cup your unit had and those assemblies appear identical.
re: thrust pad. That could very well be the source of noise at the IM pulley.
I can make one of these pads. Torlon of course;-) But now that I have 57175 all buttoned up and ready to ship, I don't know the diameter to make it. Thickness, no doubt should be 1mm.
-Steve
Steve, I'd be highly appreciative and can find out the required size sometime over the next few days/week..