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back to the TD124 Dept

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)

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DSC_2306.jpg (207544 bytes) With eddy brake magnet and adjuster  assembled.  Note heavy felt and E-clip retainer.

DSC_2316.jpg (207980 bytes) Looking into the stepped pulley bushing bores.

DSC_2321.jpg (191756 bytes) checking for size and evidence of wear. upper bushing

DSC_2322.jpg (187220 bytes) lower bushing

DSC_2323.jpg (220022 bytes) checking for size and evidence of wear on the stepped pulley shaft.

DSC_2326.jpg (193065 bytes) 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.

DSC_2315.jpg (292666 bytes) Height adjuster, lock and thrust pad for the stepped pulley.

DSC_2317.jpg (176136 bytes) preliminary assembly, loose for now.

DSC_2329.jpg (153766 bytes) 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.

DSC_2337.jpg (184006 bytes) With its drip cup installed.

 

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. 

DSC_2330 annotated.jpg (257717 bytes) Far view.  Location of the bushing

DSC_2331 annotated.jpg (197142 bytes)Close-up view....bushing

DSC_2335.jpg (131650 bytes) Measuring the pin. Size checks uniformly up down and around at  .19685

DSC_2334.jpg (291681 bytes) The bore gage (Mahr Gage) is zeroed out to the nominal ( 5mm / .1969") Measurement is determined by the number of graduations away from the nominal setting on the gage.

This gage reading is .1969 + .00125  = .1981"

DSC_2333.jpg (276878 bytes) Higher up within the bushing the read is .1969 + .0018  = .1987

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

DSC_2341 ANNO.jpg (163635 bytes) The thrust brg surface, bottom of idler wheel.

DSC_2352.jpg (149171 bytes) Axle prior to fitting of the thrust washer.

DSC_2353.jpg (190829 bytes) Thrust washer over axle.  Note the close fitting of size between washer ID and axle OD.

DSC_2354.jpg (209701 bytes) 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.

DSC_2355.jpg (162947 bytes) Once thrust washer is seated, a thin layer of general purpose lithium grease mixed with 20 wt. turbine oil is brushed on.

DSC_2356.jpg (173400 bytes) 20 wt. turbine oil is drizzled over the axle and into the bushing bore of the idler wheel prior to slipping the wheel over its axle.

DSC_2357.jpg (170226 bytes) 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

DSC_2329.jpg (153766 bytes) Once idler wheel is fitted, it is now possible to adjust vertical position of the stepped intermediate pulley relative to the idler wheel.

Looking at the result from above:

DSC_2358.jpg (120216 bytes) 16 rpm position

DSC_2359.jpg (91743 bytes) 33-1/3rd rpm position

DSC_2360.jpg (114819 bytes) 45 rpm position

DSC_2361.jpg (115790 bytes) 78 rpm position

Close enough for now.  Once the turntable is assembled and running, we'll check these adjustments again.

CLUTCH

DSC_2362.jpg (249536 bytes) prior to installing clutch

DSC_2364.jpg (270612 bytes) with clutch placed

DSC_2372.jpg (182412 bytes) pivot retainer

DSC_2373.jpg (202715 bytes) sliding retainer

DSC_2380.jpg (166590 bytes) 

Platter Bearing

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

DSC_2365.jpg (184875 bytes) 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)

DSC_2366.jpg (224891 bytes) The iron platter is placed over the spindle and rests over the bearing flange prior to fastening the 3 machine screws. 

DSC_2367.jpg (200031 bytes) after screwing the platter onto the bearing flange, a dial indicator is used to check for run-out at three places.  Here we check the OD for concentricity to the bearing.

DSC_2368.jpg (160394 bytes) Here we check for run-out on the top face.

DSC_2371.jpg (300635 bytes) Most vital check; we measure run-out at the inside rim where the idler wheel engages.  After minor adjustments run-out at this critical area was reported to .001" total.

 

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.

DSC_2374.jpg (304108 bytes) This TD124 has a version of the on/off switch I hadn't seen before.  I took several photos to document.

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DSC_2382.jpg (257324 bytes) early listening....testing.

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.