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Project sn 27520

Receiving:

Date received: 5/11/2016

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Comes with a plinth from the original period:

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Unpacking

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The light upper platter and accessories

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oem tonearm: ESL and armboard

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Flywheel

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Chassis

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DSC_2618.jpg (268190 bytes) sn# 27520  Late first version.

DSC_2619.jpg (323909 bytes)  It appears complete.

Inspection:

Chassis and paint

Before clean-up: DSC_2617.jpg (309848 bytes)

After clean with warm water and soap:

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Detail close-ups; scratches and chips (below)

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Rub-throughs:(below)

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Under view (below)

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Notes:  One highly visible deep scratch covered with an accumulation of dirt and debris left to etch into the enamel finish. --Front to the right of the strobe window.--

Two rub-through areas along the back side.  Chips in paint on the left side near the clutch lever.  Wear-through near the speed control switch (common).

Clean-up procedure was to use soft cloths, soap and warm water.  After this cleaning, the dirt is still stained deeply into the paint.  A light pollish will clear much of that.  However  the exterior finish on this and most other TD124 chassis is not of a uniform thickness.  Some areas have very thin coverage while being more normal (thicker) coverage in other areas.  Extreme caution must be taken to avoid further rub-throughs as evidenced on the back side of this deck (received that way, btw).

This seems a good candidate for light touch up to the paint.  I'll see about getting a color match to this chassis from local automotive body&paint suppliers.

Other notes: The bubble level was dry and non-functional.  This will need replacement.

DSC_2645.jpg (247788 bytes) DSC_2646.jpg (200750 bytes) dead as a door-nail

The chassis finish surrounding the bubble level is rubbed-through to bare metal.  In need of paint touch-up. DSC_2629.jpg (194692 bytes)

 

 

Parts list of needed replacements: (preliminary, to be added to as inspection continues)

Mushrooms
motor mount grommets, washers & e-clips
clutch lever pads
strobe mirror
bubble level
drive belt
platter brg housing bushing sleeves (SAE 841 porous bronze) (in stock)

E50 sn 48083

DSC_2647.jpg (307717 bytes) Checking ohms readings of the stator coils

Coil #1:
black - yellow: 55.5 ohms
black - red: 86.2 ohms
black - green: 265.5 ohms

 

Coil #2:
black - yellow: 53.5 ohms
black - red: 81.5 ohms
black - green: 259.7 ohms

It is the differences in readings between coil 1 and 2 that we are looking for.  Preferably, all comparisons would be closer than a 2 ohm difference

Differences in readings between coil 1 and coil 2:
black - yellow: 2 ohms
black - red: 4.7 ohms
black - green: 5.8 ohms

DSC_2702.jpg (154997 bytes) neon strobe bulb

Strobe Resistor:

DSC_2648.jpg (368158 bytes) reading: 37 K-ohms

Should be: within 10% of factory spec 33 K-ohms

opening the motor casing:

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DSC_2653.jpg (344013 bytes) DSC_2654.jpg (283659 bytes) Bushings after several soak sessions in acetone. Using the Mahr split ball gage I get bushing inside diameter measures to range from .1870 to .1871 inches.

DSC_2655.jpg (279280 bytes) Rotor prior to pollish.  Shaft diameters either end: .1867 inches all over and around.

Running clearance shaft to bushing: .0004 inches.

DSC_2656.jpg (215653 bytes) After first bake; 250 F for 5 minutes.  Nothing dirty oozing out.

DSC_2657.jpg (123162 bytes) After second bake; 250 for 5 minutes.  Still nothing dirty oozing out.

DSC_2658.jpg (297220 bytes) Rotor shaft after lathe pollish: .1867inches.  (nothing removed) 

Rotor pollish process: 1) machine a sleeve out of nylon round rod  .375 OD and .1875 Id.  Slip the nylon ring over one shaft end, chuck it in the lathe, insert live center in the other end of the rotor shaft.  Pollish with 1200 grit emery cloth.  The 1200 grit is so fine that no measurable amount of material was removed from the shaft.  We just have a uniform micro-smooth finish all over the rotor shaft.

Before: DSC_2655.jpg (279280 bytes)  after: DSC_2658.jpg (297220 bytes)  Little things do count when it comes to the E50 motor.

DSC_2659.jpg (476482 bytes) Oil retaining felts after several cleanings in acetone.  Felts are supple and clean.  Ready for more service.

DSC_2660.jpg (184596 bytes) Motor bushings soaking in 20 wt turbine oil (aka Thorens Oil)

Inspection; dimensional

DSC_2661anno.jpg (185638 bytes) Stepped pulley shaft and bushing bores.

Shaft diameter: .1573"

bushing bores; bushing top: .1578, bushing lower: .1575

DSC_2662 anno.jpg (235346 bytes) idler wheel carrier / speed change detail.

Bushing bore ID: varies as follows: top: .1985, middle: .1980,  bottom: .1987

Shaft diameter: .1967 inches

running clearance: top: .0018, middle: .0013, bottom: .0020

DSC_2663.jpg (241428 bytes) platter bearing shaft and bushing bores:

Shaft diameter:

Bottom (near thrust ball): .5500
mid: .5500
top: .5497 inches
Note: Bearing ball at shaft bottom, under magnification (10x) looks ok and will remain in place.

Bushing Bores:

bottom bushing (near thrust pad): .5515 inches
top bushing: .5515 / .5520 (.0005 irregular wear)

Visually, the bushing bores show wear areas.

shaft to bushing run clearances:

top: .0023 / .0018
bottom : .0018

disposition: replace bushings with new

bushing bore size with new bushing sleeves installed into the steel housing:

top: .5514

bottom: .5514

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Above photo: Platter with main bearing shaft attached.  The Shaft has been lightly pollished using 1200# emory cloth. The bearing housing has its new bushings installed.  A new gasket has been cut.

Bearing ball has been removed for inspection.  Ball checks ok, though I have some new ones standing by should there be a need. (there isn't).

Brg Shaft dimensions after pollish: .5500 to .5497 (same as before pollish)

The new bearing shaft to bushing running clearances: .0017 - .0014

DSC_2667.jpg (181393 bytes) The bearing ball is installed back into the shaft end. Clipped in place. A new gasket.  A new Torlon 4301 thrust pad.

Idler wheel and its axle:

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Pin diameter: .1968

idler wheel bore diameter: .1974

running clearance: .0006 inches.  Very Good

 

Clean-up: Chassis and paint

B4: DSC_2617.jpg (309848 bytes)

After touch-up

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DSC_2684.jpg (235807 bytes) with new voltage label

Assembly

Current status: waiting for replacement parts.  In the meantime the chassis has been assembled partially for this photo shoot below. Note the new Jelco SA-750D is mounted to its new armboard and chassis.

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Notes: Apart from the dirty and deeply scratched veneer surfaces, the plinth is sound and serviceable.  Four heavy rubber feet have been installed.  The external surfaces of the plinth have been cleaned and oiled.

Now....where are those parts?  They were ordered two weeks ago and we're still waiting!  I've been informed by the supplier that they were to have been in the mail on Thursday 6/26/2016. USPS priority mail.  It's Saturday (5/28/2016).  Wouldn't it be nice if they showed up in today's mail. 

What remains:

install bubble level into its fixture (when the part arrives)
Motor parts...needed to assemble
a new strobe mirror (glass)
Mushrooms (for the open box style plinth in the photos)
but my usual source is slow shipping this time.


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The replacement parts arrived 5/31/2016. The installation of the upgrade parts went normally.  However when I was ready to test run the turntable I found that the motor was running very low on torque and did not carry pace very well at all.  All variables checked normal except one.....the motor.  A new E50 revision stator coil set was ordered from Audiosilente in Rome, Italy.  Turnaround was fast.  I had the coils on Tuesday.  I'd placed the order the previous Friday!

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Ohms check new coil set:

Coil 1

Black - yellow: 22.3 ohms
Black - red: 70.1 ohms
Black - green: 102.8 ohms

Coil 2

Black - yellow: 22.4 ohms
Black - red: 70.2 ohms
Black - green: 103.2 ohms

Very close resistance reads. With the new coils installed, and all previously replaced parts in their places, the initial power on resulted in a motor that came up to speed in one rpm! 

 

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The Jelco SA-750D tonearm is installed to its armboard.  For testing one of my Denon DL-103R lomc cartridges is put to use.  Installation to the headshell went uneventful.  I drew and printed a custom arc protractor for this arm.  It wants a Stevenson alignment with nulls at 60.325mm and 117.42mm.  mounting distance: 214mm.  Eff.Len.: 229.  Setting overhang on this headshell went smooth, requiring scarcely any fiddling around to zero in on target.  Nice machining Jelco!   VTF was set to 2.2g using a digital scale.  VTA/sra was eyeballed putting buttom edge of the ebony body parallel to record surface.  A ballpark starting point.  My exp on this cartridge for setting vta/sra is that with the conical tip there is some allowable tolerance in finding the sweet spot.

Sound quality is very good.  Background noise is quite low.  Quiet.  The new mushrooms over an open box plinth can be a potent foundation for one slammy td124.  This one seems so.  The Jelco SA-750D does not get in the way of bass.  I like it.

I'll spin vinyl on this one for the next day or more -- if I can get away with it -- 'lest the turntable's owner tells me to ship it back to him pronto so he can listen to it.