Links (analog style) and downloads
The TD124 Motor
My example came with a spare motor. The original TD124 motor is seen to the right of the turntable. The PO had trouble with too-fast running speeds and had replaced the motor with another. Unfortunately the fast running speeds persisted. For this page I will clean and lube the original motor to see if it can be re-used.
The motor type is a shaded pole induction motor. In the above photo the two phase coils are visible on either side of the large central opening. The different colored wires are for different operating voltages. Black for 100-120. Yellow for 125-150. Green for 220-250 volts. The red wires are for AC mains.
Looking inside the casings after many, many years of use and then many years of non-use. The lube reserve held within the felts has dried and turned to wax.
The bushings are contained within an assembly of felt pads, spring collar and cover. These are originally held in place with hollow rivets. To service the bushings the rivets were drilled out. I've seen photos of these motors far more gunked-up than this one was.
Take a look at the bottom end cap with the white plastic thrust pad. The small bearing ball rides between the pad and the countersink within the end of the rotor shaft. Wear is indicated by the indentation within the white pad.
Some of the parts. The white plated parts were allowed to soak in Berryman's B9 Carburetor cleaner. After 1/2 hour they came out free of crud and shiny. The carb cleaner can also strip paint. Caution is in order. Caustic skin irritant, eye melting acids! The bronze spring retainers were simply washed in lacquer thinner and wiped dry. On second thought, these could have also benefited from a soak in the carb cleaner, but they will be functional as is.
The sintered bronze bushings after the first cleaning. First the bushings were baked at 250 deg. F. A dark greasy substance oozed out. Following that they were washed in a jar filled with lacquer thinner then allowed to dry. Next I put the bushings back in the oven just to see if any more crud might run out. It did. More black ooze. Another cleaning with lacquer thinner, then allowed to dry. Next I placed the bushings in a container of lube and put this into the oven at 250F. After several minutes they were removed from the oven and allowed to cool while still submerged in the lube. Next I removed the bushings from the tin filled with lube and then placed them in a disposable pie tin to be baked dry at 250F. No more black ooze. Once more the bushings were put in a container filled with fresh lube and baked at 250F for a few minutes, then removed and allowed to cool. Now they were ready to be installed. the lube being used is Valvoline 80/90wt hypoid Gear oil.
Note the spherical ends. This feature makes possible a limited amount of alignment adjustment between the upper and lower casings once all of the parts are assembled.
About the oil reserve felt pads: It might not be felt as previously thought. The texture of the pads appears sponge-like. The sponge pads were still intact with good shape. These I lightly cleaned by soaking/washing in a lacquer thinner bath, then allowed them to dry. this was followed by a soak in a container of lube at room temperature for several minutes. I've noticed that the pads do retain the lube. In effect, the lube did not immediately evacuate once the pads were removed from the soak.
Bearing end cap, thrust pad and ball, after cleaning. The end cap went into the carb cleaner. The ball and pad were simply wiped clean with a paper towel. The bearing ball mic's at 2mm in diameter. The pad measures 1mm thick.
Without the ball. The previously used indented side is now faced down. The unused side provides a flat new surface to engage the thrust ball. I'll try it this way for now. Perhaps, later on, a heavy bronze end cap with a fresh Delrin thrust pad could be made for this! I'll put that idea on the back burner for something to try at a later date. Also, the bearing ball could be replaced with another one of different material.
The lower bushing after a few cleaning and lube cycles. It awaits to be inserted into the spherical socket of the end case. The end cap with thrust pad is positioned to receive using m2.5 x .45 machine screws The larger oil retaining sponge pad is laid against the end case.
The bushing is inserted with its spherical end fitted within the spherical socket of the end case.
The inner cap is partially assembled with the smaller sponge pad and the bronze bush retainer spring. it is ready to be fitted over the bushing end and onto the case.
After fastening the bearing assembly onto the lower case. The inner cap tensions the bushing while allowing the bushing to be rotated a small amount within its spherical socket fitting. The m2.5 hex jam nuts were carefully ,and somewhat tediously, fitted with my fingers to engage the threads of the machine screws. Once the nuts had a 'start' on the threads I used a screw driver to engage the slotted end of the screw while holding the hex nut with a small plier. In this way I was able to tighten the assembled bushing quite firmly to its end case.
The bushing assembly is installed to the upper case the same as the lower but with the exception that there is no end cap. The rotor shaft fits through the upper case.
Another view of the end cases after cleaning and reassembly of the bushings.
The thrust ball, in my example, is magnetized and sticks itself to the end of the rotor shaft. Very handy for assembly and disassembly.
Above three photos: To assemble the motor I fitted the rotor (with thrust ball stuck within the c-sink at end of the shaft) into the bushing of the lower case. Then the stator core was slipped over, then the upper case. Care was taken to align the wire harness and fit it through the intended port of the upper case. Note the photo showing the position of the posts. these fit up through the cast chassis for mounting and must be oriented as shown.
Btw, the motor in the above photo is not yet fully assembled but is complete enough to make preliminary bushing alignment adjustments.
Here the motor is after cleaning and re-assembly. It is being tested for quiet running using a Viz isotap isolated power supply (with adjustable output) and a mechanic's stethoscope. The axial alignment of the upper and lower bushing was "tweaked" until quietest running was heard through the stethoscope. One positive thing I noticed is that this motor will turn and run on 25 volts AC. I take that as a sign of the motors overall good health.
For alignment adjustments I set the output of the Viz and connections to the motor at 100 volts. I began by leaving the four fasteners just slightly tensioned. Then, with the motor running in my hand, and by lightly tapping the upper and lower covers with the plastic end of a screw driver at various places, I could minutely adjust position of the end cases. This DOES alter the noise level and noise character of the running motor. I settled for the quietest noise level I could get. After several minutes of running the motor became quite warm in my hand but did not become so hot as to burn me.
Next: After the motor has been installed to the turntable, and the belt has been fitted, and while the motor is running and fully warmed up, under load, I will make further bushing alignment adjustments using the stethoscope.
Much more to come.
detail close-up of the TD124 motor wire-up
Reference in use:
http://homepage2.nifty.com/pantone/thorens/overhaul_1.htm I found this link to be a very useful reference guide. It shows step by step disassembly and reassembly, and also details the electrical connections. Highly recommended.