I've used the heating process, learned through the experiences of Kevinkr and others as documented in this thread. It does work quite well. In fact, I've posted a few Youtube vids showing my luck with the process.
My only concern with it is the effect certain temperatures may have on some of the old oils (of unknown types & combustion temp points).
As others have noted, the old oil when coming out sometimes appears very dark, a characteristic normally written off as evidence that the old oil was badly contaminated. Some of my own efforts have also brought out dark oil, but when watching the "cooking process" closely, even at temps that according to my thermometer are below 200 degrees, I have occasionally seen some wisps of smoke, accompanied by a tell-tale burning odor. Is my thermometer off that much? I suppose it's possible, but again, I've no way of knowing exactly what are the characteristics of the oil (or a mixture of oils) in a bushing that may have passed through many hands over the decades.
My concern has been the possibility that what we are seeing, the dark oil, is not the result of just the age of the oil and impurities getting into the bushing over time, but actual combustion byproducts caused by heating the bushing past the unknown oil's combustion point - and that some of these byproducts might be getting left in the bushing.
Anyway, that was the main reason I was wondering if the vacuum chamber might be a viable alternative for evacuating old oil as well as for infusing new bushings. Even in instances where new bushings are used, there may be times when they are infused with an oil other than what I'd prefer to use.
My only concern with it is the effect certain temperatures may have on some of the old oils (of unknown types & combustion temp points).
As others have noted, the old oil when coming out sometimes appears very dark, a characteristic normally written off as evidence that the old oil was badly contaminated. Some of my own efforts have also brought out dark oil, but when watching the "cooking process" closely, even at temps that according to my thermometer are below 200 degrees, I have occasionally seen some wisps of smoke, accompanied by a tell-tale burning odor. Is my thermometer off that much? I suppose it's possible, but again, I've no way of knowing exactly what are the characteristics of the oil (or a mixture of oils) in a bushing that may have passed through many hands over the decades.
My concern has been the possibility that what we are seeing, the dark oil, is not the result of just the age of the oil and impurities getting into the bushing over time, but actual combustion byproducts caused by heating the bushing past the unknown oil's combustion point - and that some of these byproducts might be getting left in the bushing.
Anyway, that was the main reason I was wondering if the vacuum chamber might be a viable alternative for evacuating old oil as well as for infusing new bushings. Even in instances where new bushings are used, there may be times when they are infused with an oil other than what I'd prefer to use.
Thanks. I had been looking at those and even the smaller 35mm versions. Nice to know that they are very quiet. I really don't know how much torque is needed to driver a TT platter. Considering the low RPM and consequent low 9:1 gear ratio, maybe a lot?This is the one I'm considering:
It's 49mm diameter, 3 watts, with 2.7 oz-in torque.
Precisely the the problem with my big old Rek-O-Kut motor. Just idling it's tolerably quiet. But once pressed against the pinch roller and platter, the noise is very annoying. At least Thorens put in a little belt.
Guys, we've drifted pretty far from the intent of this thread - let's move these posts and start another thread.
(Preceding post excluded - it's on topic)
Chop out what you want to Kevin and put it in a new place. Sorry to drag this O.T. - there is just so much good info here.
e50 stator coils
re: post #1154
Just an update on the new E50 replacement stator coils that I purchased from Simone Luchetti. It has been several months now with the updated motor and tt behavior is now very stable and repeatable. With some sensitivity toward ambient temperature.
I think the older (mk1) models giving irregular and slow start-up times might be operating on coil sets which may have seen too much heat too often and have partially melted through their insulation. I do believe that an important component of stable motor speed is the temperature at which the motor operates.... and worn coils cause it to run too hot.
just sayin.
-Steve
re: post #1154
Just an update on the new E50 replacement stator coils that I purchased from Simone Luchetti. It has been several months now with the updated motor and tt behavior is now very stable and repeatable. With some sensitivity toward ambient temperature.
I think the older (mk1) models giving irregular and slow start-up times might be operating on coil sets which may have seen too much heat too often and have partially melted through their insulation. I do believe that an important component of stable motor speed is the temperature at which the motor operates.... and worn coils cause it to run too hot.
just sayin.
-Steve
Thread has been cleaned up and brought back on track.
jr186262 Continually posting about some guru who is reputed to work magic on these products, and yet refusing to share that information with others is not what this forum is about.
If you wish to promote 3rd party services then there are other more suitable channels for you to do so.
No shims needed. It did require careful alignment between the separate pieces in order to fit the 4 pins that hold the coils in place. The pins, btw appear to be aluminum and will bend easily. Pin diameter is 2mm. I find that a bicycle spoke can be found in the same diameter but in different materials depending on the spoke. I did substitute one stainless steel spoke (trimmed to length) to replace one hopelessly bent pin. Assembly does require some care.
I detailed the process in an earlier post here to this thread and at a page on my site.
13943
The hook-up wire on these coils come extra long so you can trim to length as you solder them to the terminal board.
Whatever effort it takes to install, the end result has proven well worth it. I plan to replace the coils on my two other TD124 players with these from Simone.
After several months, operation behavior is entirely predictable. On a cold start it takes maybe 2 platter revs for the strobe to hit steady, then a couple of seconds later there is a momentary slight speed-up followed by a slight slowing, which gradually recovers back to target in a few minutes. And all of this is close enough to target speed to be playing a record. The best motor behavior I've had on one of these.
Based on what I've seen so far, I suspect (intuitively) that we need to consider another factor in our motor rebuilds. That is that motor rpm is affected by the running temperature at the stator coils.
Things to consider:
There is some increased drag felt due to cold lube, where the drag factor reduces as the lube comes up to normal operating temp.
Another factor is the eddy brake magnet adjustment. Another source of drag.
Then there is voltage input. We know that an increase by as little as 5 volts AC can change motor rpm enough to be seen on the strobe.
Correct running clearance between rotor and bushings. Often assured replacing bushings with new ones and a light polish to the rotor shaft. Careful with sizing. I use crocus cloth.* (a rubberized abrasive that doesn't reduce shaft size)
We take extreme care in aligning the upper and lower case halves as part of our process. This minimizes drag between bushing and rotor shaft.
Now add stator coil temperature into the equation. I do believe that as the coils change temperature, motor rpm also changes. I think this because with the new coils I have a very stable strobe window all day long with hardly any need at all to compensate with the pitch knob. The new coils are temperature stable, therefore the motor is far more speed stable. This is what I think.
#2729 will be the next player to get new coils. That player dates back to the late '50s. Old coils.
-Steve
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Copper has a quite large positive temperature coefficient of resistance, the motor generates a back emf and the output power is detemined by the forward current through the coils.
Take these three together and it explains why coil temperature affects speed.
If it helps anyone, 2mm stainless spokes are also known as 14 ga.
They are usually made of cold drawn 304 wire. If you heat one to red hot with a torch and quench it in water, it will become quite soft and lose any remnant magnetism. The drawing process re-aligns some of the austenite to martensite, raising the permeability, annealing as above re-forms the austenite.
Take these three together and it explains why coil temperature affects speed.
If it helps anyone, 2mm stainless spokes are also known as 14 ga.
They are usually made of cold drawn 304 wire. If you heat one to red hot with a torch and quench it in water, it will become quite soft and lose any remnant magnetism. The drawing process re-aligns some of the austenite to martensite, raising the permeability, annealing as above re-forms the austenite.
And the next item to address on this subject of coil temps is why older coils might cause the e50 to run less speed stable. The only thing that comes to my mind is that with repeated exposure to high temperatures, the wires start to burn through (melt) their insulation. The ultimate result would be a complete burn-thru and a short circuit, stopping the motor. But prior to that extreme, partially burnt insulation must be a factor.
Steve
I shall have to think about that, but it accords with the behaviour of industrial induction motors such as those we use in wineries for pumps etc.
They are routinely tested for insulation resistance (known as a "megger" test, short for megohm meter) because overheating the motor causes insulation leakage which causes inefficiency which causes overheating which causes ...
This would contribute to long term speed problems due to thermal cycling for the reasons outlined above. I'm not sure about short term speed instability, I haven't thought about it and it's not something we'd really notice: pumps often show short term cycling due to such things as resonant effects in pipework.
BTW I should have added to my post above:
Forward current = (drive voltage - back EMF) / coil resistance
They are routinely tested for insulation resistance (known as a "megger" test, short for megohm meter) because overheating the motor causes insulation leakage which causes inefficiency which causes overheating which causes ...
This would contribute to long term speed problems due to thermal cycling for the reasons outlined above. I'm not sure about short term speed instability, I haven't thought about it and it's not something we'd really notice: pumps often show short term cycling due to such things as resonant effects in pipework.
BTW I should have added to my post above:
Forward current = (drive voltage - back EMF) / coil resistance
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The Megger will show a leak to the test probe.
A turn to turn leak, where the internal insulation has failed, will not show in the Megger test.
A check on current drawn will show as turns short out.
Lower turns equals lower inductance and lower resistance.
Those combine to draw more current than a "not failed" set of coils.
A turn to turn leak, where the internal insulation has failed, will not show in the Megger test.
A check on current drawn will show as turns short out.
Lower turns equals lower inductance and lower resistance.
Those combine to draw more current than a "not failed" set of coils.
At one time I owned three E50 of differing vintages, and all clearly had differently constructed windings. My understanding is that the last revision to the windings relatively late in the original 124 series was intended to mitigate the heating issues.
The motor in my MKII definitely runs slightly cooler than the motor in my older "MKI" which has what I call the "middle" motor - I had an earlier one from a table with a much lower serial #.
The MKII motor runs slightly slow when cold and as the table warms up comes up to nominal speed, this can take a couple of minutes to 20 minutes depending on the temperature of the listening room. Once warm it is extremely stable and this table rarely needs adjustment.
The older table runs slightly fast and slows down as it warms up, this would be consistent the behavior with higher copper losses as the windings heat up. (Torque is related to effective line voltage across the winding)
I think the improvement is largely due to reduced heating during operation and hence a smaller variation in torque during warm up..
I would expect any winding with an internal short would probably burn out in short order.
The motor in my MKII definitely runs slightly cooler than the motor in my older "MKI" which has what I call the "middle" motor - I had an earlier one from a table with a much lower serial #.
The MKII motor runs slightly slow when cold and as the table warms up comes up to nominal speed, this can take a couple of minutes to 20 minutes depending on the temperature of the listening room. Once warm it is extremely stable and this table rarely needs adjustment.
The older table runs slightly fast and slows down as it warms up, this would be consistent the behavior with higher copper losses as the windings heat up. (Torque is related to effective line voltage across the winding)
I think the improvement is largely due to reduced heating during operation and hence a smaller variation in torque during warm up..
I would expect any winding with an internal short would probably burn out in short order.
Motor speed and temperature
On four E 50 motors I made the following measurements
Mains voltage 228 Volt Room temp 20 degrees new bearings without belt !
resis.cold speed resis.hot degrees speed
Motor ser.no 1487 695 1440 820 38 1440
Motor ser.60000 390 1447 445 40 1445
Motorcoil Simone older 400 1450 470 39 1450
Motorcoil Simone lattest 350 1460 386 39 1465
Speed stabilty was ok for all the motors after the complete revision off course .
There is some spread in the motors and voltage but the min speed from about 1440-1450 rpm must be ok at first start up, without belt !
Volken
On four E 50 motors I made the following measurements
Mains voltage 228 Volt Room temp 20 degrees new bearings without belt !
resis.cold speed resis.hot degrees speed
Motor ser.no 1487 695 1440 820 38 1440
Motor ser.60000 390 1447 445 40 1445
Motorcoil Simone older 400 1450 470 39 1450
Motorcoil Simone lattest 350 1460 386 39 1465
Speed stabilty was ok for all the motors after the complete revision off course .
There is some spread in the motors and voltage but the min speed from about 1440-1450 rpm must be ok at first start up, without belt !
Volken
I think you have to test also under full load* conditions. Then we can compare an unloaded test versus loaded and see if motor speeds are as consistent. Expect somewhat lower rpm under load but compare the cold versus warm same as done under no-load conditions.
* on a fully operational TD124.
-Steve
Yes but thats not so easy because to measure the speed from the motor you must have room to measure when it sits on his place.
I expect that the difference is not so much the motor slip become a little bit more and depents from the eddy current brake , idler/platter.
But I shall try it maybe I can measure the belt speed on the underside from the chassis.
Volken