TD124 project sn #57175
Above: receiving photo. the turntable came to me in 'near' complete disassembly. The parts received are clean and appear ready for assembly. However there will be measurements taken to reveal any evidence of wear on friction surfaces such as bushing bores/bearing shafts, thrust pads etc.
More details to come.
So far. A TD124 delivered in pieces.
Chassis sn# 57175 (later serial number, first version)
This check indicates a running clearance between bushing bores (upper and lower) and the bearing shaft of the stepped pulley. Clearance = .001 inches. Bushing bores check straight and round. The micrometer could not reach into the entire length of the pulley shaft, but visual evidence supports what measured evidence exists to suggest the shaft surface appears nominal and ready for assembly.
adjusting height of the stepped pulley from this point. This method will be used to position stepped pulley height relative to the idler wheel once the turntable is fully assembled and ready for testing.
Checking the speed shift mechanism. A critical part of this assembly is a cam follower bushing that positions the cam follower linkage assembly that positions the idler wheel for different speed selections.The bore gage (Mahr Gage) is zeroed out to the nominal (Ø 5mm / .1969") Measurement is determined by the number of graduations away from the nominal setting on the gage.
This gage reading is Ø .1969 + .00125 = .1981"
The running clearance between pin and bushing bore: .0013 to .0019 inches. By design the pin movement within the bushing is to be vertical only. This pin/bushing fit is important in maintaining position of the idler wheel relative to the stepped intermediate pulley that drives it. Bushing material appears to be Oilite (porous Bronze)
IDLER WHEEL SETUP: Thrust washer
To take the vertical thrust of the idler wheel, a lathe-turned Tecapeek thrust washer has been made. Dimensions: size for size between axle shaft and washer ID. So that the washer will not spin. Thickness: 1mm.
A retainer collar is held in place via two set screws. Care is taken to allow a slight gap between upper face of the idler wheel hub and the bottom surface of the collar. No rub allowed. A small gap is preferred.
ADJUSTMENT VERTICAL POSITION STEPPED PULLEY TO IDLER WHEEL
Looking at the result from above:
Close enough for now. Once the turntable is assembled and running, we'll check these adjustments again.
As found, the bearing shaft was too tight within the bearing sleeves of the housing. The likely cause of the tight bearing shaft would have been that the sleeves were not pressed in with enough attention toward getting the sleeves squared up to the housing bore. The effect in such a situation is a deformation of the soft Oilite Bronze sleeve resulting in excess out-of-roundness and a reduction in sleeve-to-shaft operating clearance. The fix was to press out the deformed sleeves and press in new ones. With the new sleeves the running clearance between shaft and bushing bores are within nominal tolerances and the shaft spins freer than before while exhibiting proper running clearances. (.001")
The original flexy thrust cap appeard to be in good condition and was retained. A new gasket seal was made. The original Nylatron thrust pad was retained by simply turning it over to a fresh unused side..
Installing and Aligning the Platter
Bearing is mounted. In the bearing housing new sleeve bushings have been pressed in. A new gasket seal is installed at the bottom cap. The original nylatron thrust pad had one fresh unused side, so we are using it now. Lube in bearing is a match to the requirement in the TD124 service manual....20 wt. turbine oil. (Modern equivalent)
E50 Motor Maintenance.
This E50 has apparently received service in recent years. Rotor bushings appear to have been replaced. So have the oil retaining felts. I found a Ceramic Silicon Nitride bearing ball at the thrust end of the rotor. This has to have been a recent upgrade. My purpose in this instance is to observe the assembly, check wear areas for evidence of wear, clean, lube, reassemble. Install to the TD124 chassis. Make the electrical connections. Make adjustments of the motor/rotor for centering. Running in period. Final adjustments motor/rotor centering.
RPM comes up within 2 revolutions. Will listen to it this way for several hours, then make rotor/centering adjustments.
Initial listening impressions: Excellent rhythmic drive and energy. This coming from the turntable sitting without mushrooms on an open box plinth. Mk1 style single grommet motor isolation mounts. No rumble heard during stylus drops, in lead-in lead-out grooves.