Siting a GL78 deck into a L75 plinth.

[Green Bean]

Thanks to member Jonpw98 for his kind donation of an L75 plinth, here is my first ever foray into turntables, starting with this conversion.

Bought a Dynatron Music Centre off ebay. It was clear the GL78 deck was in great condition. But I had some issues with getting a viable MM signal out through the old 5-pin DIN tape outlet - mentioned elsewhere in this site.

All I've had to do other than snip a few wires, is cut two wooden mounting blocks off the new plinth, as it seemed to me they were not at the right height to accommodate the cast mounting protuberances on the underside of the deck.

I'd be grateful for advice now. Can I simply feed a 240v mains feed direct to the motor, or is there some kind of current-regulating component I need to fit between the feed and the motor? I imagine motors prefer DC.

And does anyone have a use for the leftover Dynatron gubbins? The plinth and acrylic top are in very good condition.

https://postimg.cc/gallery/dkWM2h3

[analogadikt]

Lenco motors work on AC , not DC.

Please read this and confirm how your motor is wired.
https://www.lencoheaven.net/forum/index.php?topic=68.0
Music centre motors are sometimes wired for 110 volts. Feeding 240 volts to them would damage the coils.

Regards,

Anwesh

[Green Bean]

Thank you Anwesh. You have answered my question well.

[analogadikt]

free pic upload

It looks like wired correctly for 220 volts. Just check that the blue and white coil wires are coil A to 1 and 2 from left and coil B connected to 3 and 4 from left in the above pic.

Regards,

Anwesh

[Jonpw98]

Looking good Tom.

Glad you got it all wired up and pleased you could make use of the plinth.

Jonathan

[Green Bean]

Am reaching the end of this project.
Have fitted an IEC C14 socket and a pair of phono sockets.

My question to the community is this:
Can I connect the earth wire from the tonearm to the earth pin of the IEC socket? I can't connect it to the amp as the amp does not have a ground terminal. Eventually, the plan is to use a WIIM as the phono stage. But I'd like to make my decision about earth-wiring now, as I seek to finish the plinth project.

[damiena]

I usually do not connect tonearm ground to the safety earth. Unless it's the only way to get rid of a hum. I get better results connecting it to preamp/amp chassis.

Results may vary in your system though, and you need to test what works best.

Have you read all this? https://www.lencoheaven.net/forum/index.php?topic=19831.0

[Green Bean]

Fabulous Damien, thank you.

[damiena]

Out of interest, have you earthed the top plate and motor directly to the electrical safety ground (via the IEC ground)?

There is a useful guide on this here - https://www.lencoheaven.net/forum/index.php?topic=71.0

And a few replies down a guide to disconnecting the tonearm grounds, in case the above procedure has introduced a hum/ground-loop into your system (though it sounds like you may not have this style of connection block in your system? I share it anyway as may help show the principle of keeping the cartridge and safety grounds separate and why you might want to)

https://www.lencoheaven.net/forum/index.php?topic=71.msg183748#msg183748

[Green Bean]

Interesting that you should mention that Damien. I have just in the last few minutes rigged up precisely such a system to earth the top plate/motor. Thanks for mentioning it - it helps reassure me I'm on the right path. My A-level physics is but a dim 40-year ago memory, but combined with the help on this forum I feel I can enjoy the problem-solving involved.

Here are pics of my two wiring groups - tidied and prepared and ready to solder - and the plinth I've prepared.

[Green Bean]

Here is a link to a gallery of pics of the old Dynatron Music Centre plinth.

https://postimg.cc/gallery/6R08R3K

[tabarddn]

Welcome & good luck with the project. However one thing to realise is that the Lenco plinth is made of veneered chip board, this material sucks the life out of the music and the 1st upgrade should be to make/buy a solid plinth of decent material.
for more reading on the effects of plinth materials, take a read of this TNTAudio online mag review of the difference plinth material can make to the sound of every T/T.

https://r.search.yahoo.com/_ylt=AwrOu2eL4VNm_WErSKDzZgx.;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1716802060/RO=10/RU=https%3a%2f%2fwww.tnt-audio.com%2fsorgenti%2fteemaudio_kit2_e.html/RK=2/RS=5C9sDmBGqjeOMnakXLiayhqohyI-

Cheers Derek

[analogadikt]

Welcome & good luck with the project. However one thing to realise is that the Lenco plinth is made of veneered chip board, this material sucks the life out of the music and the 1st upgrade should be to make/buy a solid plinth of decent material.
for more reading on the effects of plinth materials, take a read of this TNTAudio online mag review of the difference plinth material can make to the sound of every T/T.

https://r.search.yahoo.com/_ylt=AwrOu2eL4VNm_WErSKDzZgx.;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1716802060/RO=10/RU=https%3a%2f%2fwww.tnt-audio.com%2fsorgenti%2fteemaudio_kit2_e.html/RK=2/RS=5C9sDmBGqjeOMnakXLiayhqohyI-

Cheers Derek

That review has used used materials like MDF , sand , IKEA board granite etc , not proper chipboard as used by mainstream manufacturers back in the day.

Chipboard has good damping properties that are essential for damping the vibrations of the powerful Lenco motor. Many members of this forum enjoy their Lencos sat in original plinths.
In fact , not only tts , famous speaker brands such as JBL, Tannoy , Wharfdale, Philips etcall used chipboard for their cabs .

Regards,

Anwesh

[bazzast]

I've used chipboard on both my Lenco, to my ears sounds good.

[Green Bean]

I’ve finally got it properly sorted, following steep learning curves with a soldering iron and a multimeter.
It needed a quality pre-amp also, and not just a basic solid state. This one was just £70 on ebay and makes so much difference.
I know that technically, CDs are supposed to sound better, but I’m not interested in them. I did not know vinyl could sound so good, and I’m still beginning, using just a basic £13 stylus.
Your gift of the plinth has ignited a real joy. Thank you.