My Rek-O-Child (Record Lathe)

[Gus]

Hi!
Here is the Fairchild 539 lathe, the photo taken from ebay who has listed in 2013 and it has sold for 1.230 Euros or 1.649$ but not by me

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After one month the winner removes the overhead included the cutterhead and sold it to me for 310$
i think it was a good deal

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so my new project starts on August 2013 .

to be continued...

[Gus]

Here is what i've received

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so after 70 + years it's time to disassembly it for a good clean, re lube and repaint!

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[Gus]

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[Gus]

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[Gus]

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to be continued...

[Gus]

After a good clean with many chemicals all the parts are shine like new

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[Gus]

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[Gus]

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[Gus]

Before

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After

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it's time to check the cutterhead

[Gus]

First of all i didn't like the idea of Allen screw i would like to be able to remove the cutting stylus with my fingers.
what i did was to make my own screw

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Also as you can see i swap the Allen screws of damping blocks with Phillips Screws because the difference of U.S vs E.U. Allen key sizes

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This nice document of B.B.C writes the d.c. resistance of Fairchild 541A must to be 132 Ohms that means the head works with old school 500 ohm amp.
http://downloads.bbc.co.uk/rd/pubs/reports/1948-32.pdf

After a Deep Breath... YES!!! My multi-meter writes 131.3 Ohms that means the cutterhead seems to work.

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70 + years, is a good idea to recharge the magnet for how to you can read more infos at this useful thread http://lathetrolls.com/viewtopic.php?f=1&t=5207&p=34753&hilit=remagnetize#p34753

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Now it's time to find the suitable amp for the cutterhead.

To be continued.

[Gus]

Suitable amp for Fairchild cutterhead is UNIT 540 AMPLIFIER - EQUALIZER very rare and very expensive these days.

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Second option was to build my own tube amp with 500ohm output or to find a P.A. amp with 100volt output.
Third option was an amplifier and reversed 100 volt line transformer.
i found at my storeroom a new 300w car amplifier

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i had bought it for my E30 but never used

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[Gus]

With the help of member markrob i've found the correct transformer for my amplifier and cutterhead.

Connect the 100V, 15 watt tap to the head which will be a pretty close match to a 500 ohm head. You can calculate the secondary impedance from R = (V squared) / power. In this case: 10000 /15 watts = 667 ohms).

Mark

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As PSU to drive the amplifier i've used a 500watt P.C. PSU

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1Khz @ 0db sine wave

And it WORKS!!!
As you can see my multi meter reads 22 Volts AC

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To be continued.

[Gus]

As the owner manual writes the overhead pitch work through turntable's worm and gear at 98,118,141,161 lines per inch
what i did was to remove the gears and to install direct at feed screw a stepper motor controlled at different speeds electronically via arduino
as you can see it works pretty well

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Now it's time to find a powerful and stable turntable for my Fairchild overhead.

[Gus]

My first attempt was the Stanton SP-150 turntable with VERY powerful motor 4.5kg/cm torque very stable speed and no audible wow effect to test recordings at different speeds.
Here is a sample file embossed on polycarbonate @ 33.3 RPM with sapphire stylus and Fairchild cutterhead at 500 ohm .
Original File
http://www.lathetrolls.com/download/file.php?id=492
Embossed File
http://www.lathetrolls.com/download/file.php?id=491

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https://www.youtube.com/embed/-Hyia4L1aZ8

[Gus]

After hundreds tests on polycarb with sapphire stylus I've noticed some songs with many high frequencies as the example of the attachment file, the sound goes up and down. I think this called flutter effect if i'm wrong please correct me.

original file.mp3

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The reason is the eccentric of the platter, i measured it with Dial Indicator and it gave me 0.10mm runout. Also the wow& flutter of Stanton ST-150 is 0.10.
I have two choices the first is to build a new one platter at the local machine shop
and the second choice is to give a try to a Rek-o-Kut turntable of the 50's.
I'm going with the second...

[Gus]

The postman knocked on the door, outside of my home was a medium size box with a vintage REK-O-KUT LP 743 transcription turntable. http://www.vinylengine.com/library/rek-o-kut/lp-743.shtml

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I hate the solution of car inverter 12volt to 110v @60hz actually 63hz because of the radiation but is a cheap solution just for my tests

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[Gus]

So after 60 years of use it's time for restoration.

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[Gus]

First of all it's very important to rebuilt the motor.
you can find information at this post http://audiokarma.org/forums/index.php?threads/inside-look-of-the-death-cube.653231/

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[Gus]

After complete rebuild i add three new rubber grommets.

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[TheCrates]

Impressive work! Congrats!