Lenco 75 project, some problems

[Ropie]

Hello,

This is my first post here though I am fairly experienced in diy hi-fi, so greetings to all fellow builders

I am nearing the end of a Lenco 75 refurbishment that I have been working on for the past few weeks. With all the great help I have found on the internet it has been a relatively pain-free process so far. The photo below shows the turntable in question.



The L75 seems to be an old one and has a metal idler wheel. I have housed it in a 5-layer ply plinth, resprayed the top black and set it up with an RB300 (in a new hole, correctly aligned - cutting the hole was the toughest part of the whole project!) Now I have one or two problems to iron out and was looking for some pointers or advice.

Firstly, the motor is quite noisy. Mechanically it is very smooth but the laminations hum audibly. Is there any way to fix this or is it just a sympton of an old motor? I have otherwise cleaned, re-lubed it, etc.

Secondly, and this may or may not be related to the above, speed stability is not perfect. There is a barely noticeable 'wow' when playing LPs. It could be my imagination but I think it is worse on the outer tracks??

Thanks in advance for any help or suggestions.

[Darren D]

Are the motor transit screws set correctly, they are usually red in colour with slotted heads.

If they are done up tight as they should be for transit then this may be your problem.

If the motor is suspended correctly then it sounds as if the motor itself has a problem and may need to be replaced.

Regards
Darren

[Ropie]

Originally Posted by Darren D

If the motor is suspended correctly then it sounds as if the motor itself has a problem and may need to be replaced.

The transit screws have been removed.

I didn't make a note of the order of the motor suspension springs when I dismantled the deck but have put them back so the motor at least looks level. Could a slightly incorrectly mounted motor cause speed stability problems?

Thanks for the reply

[spikeyfaz]

Originally Posted by Ropie

Could a slightly incorrectly mounted motor cause speed stability problems?

I don't think so. I've removed and replaced a couple of Lenco motors only to notice much later that I'd got it a bit wrong but still played ok. Still, as you are fairly experienced in diy hifi I am sure taking the motor off and moving the springs around would present little problem to you .

There is a spring that pulls the idler-wheel over in contact with the motor spindle and the bottom of the platter. You could try replacing it with a slightly stronger spring. Might also be worth cleaning the idler wheel and the underside of the platter as it could be slipping.

Are you sure it's definitely the laminations that are humming? If it is knackered a replacement motor shouldn't be hard to come by. It may be easier and possibly cheaper to buy another deck and canabalise it for the relevant parts (not a bad idea to have some spares). I'm sure our old friend Mr Ebay will oblige.

I like the black finish on your Lenco. Goes well with the Rega arm. It's not clear from your photo but have you got the arm tracking level with the platter? If not you might want to consider putting a piece of packing between the cartridge and headshell to level things up.

[Ropie]

Originally Posted by spikeyfaz

There is a spring that pulls the idler-wheel over in contact with the motor spindle and the bottom of the platter. You could try replacing it with a slightly stronger spring. Might also be worth cleaning the idler wheel and the underside of the platter as it could be slipping.

I'll try a better spring arrangement as you suggest. The platter and idler wheel are as clean as whistles.

Are you sure it's definitely the laminations that are humming?

I think so. If I tighten the motor 'nose' adjustment screw just enough for the spindle to stop moving the hum remains the same. It has that familiar, painful 50hz tone to it too!

I like the black finish on your Lenco. Goes well with the Rega arm. It's not clear from your photo but have you got the arm tracking level with the platter? If not you might want to consider putting a piece of packing between the cartridge and headshell to level things up.

Cheers, it's the same black metal spray paint I used for the turntable. I originally though the black on black would look odd but it's actually not too bad! The arm hole geometry is now correct but VTA is off of course, though I had read it makes little difference. What do you suggest for packing?

[spikeyfaz]

Originally Posted by Ropie

What do you suggest for packing?

I've used a small piece of plastic sheet obtained from my local model shop. I'm sure though that there are other materials you could use. I seem to recall a thread on this site advocating the use of coasters (suitably cut down of course). A bit of veroboard might do.

Francois has a motor for sale here: http://www.lenco-lovers.com/forum/viewtopic.php?t=83

Don't know what p&p from France might cost.

[Ropie]

Originally Posted by spikeyfaz

I'm sure our old friend Mr Ebay will oblige.

There is a GL-72 for sale right now but I am not sure if the motor is the same as the 75 - anyone know??