LENCO L75 (Restoration)

[fermaleb]

LENCO L75 (Restoration)

Hello everyone! My name is Martin, I am new to LH and this is my first work. My English is not very good, so I am going to use a translator.
Here my presentation:
https://www.lencoheaven.net/forum/index.php?topic=40918.0

I recently got my first lenco (L75) for just $12 on an auction site. The young man said it belonged to his uncle. The acrylic cover was broken, stuck with packing tape. Headshell without the top and needle was broken/bent.
   
As I take it apart I see that it is actually in better condition than I expected.

In principle I will try to restore it to its original form (as far as possible)
Key Points: Motor, Idler wheel, platter, Bearing, Tonearm, wires.

comfortable place to work



The first thing is the motor
I have disassembled and lubricated it following the steps of the "motor lubrication procedure" in lenco guides:
https://www.lencoheaven.net/forum/index.php?topic=2087.0

I found one of the Sinterbronze bearings with a small mark on the outside, as if beaten. I understand that this part does not rotate and therefore should not affect the operation... (is this correct?) unfortunately I did not take photos before reassembling it

then I centered the motor coils. lenco guides:
https://www.lencoheaven.net/forum/index.php?topic=2088.0

I think the rotor edge has been rubbing at some point (left side)
I cleaned it with isopropyl and re-centered it


I have replaced the thrust pad (inside the Nose spring setting screw) because it didn't look very good:
https://www.lencoheaven.net/forum/index.php?topic=6100.0

the "mark" is not in the center. I guess this would affect the centering of the Motor shaft



and... have I checked that the coils do not make noise? running the motor without the rotor
(could it make any noise this way?)


With all this, having the motor resting on the workbench, I can't say that it is really quiet.
So the first question is: is this normal?

Video:

[aamodtasan]

Good job! Sounds like the ones I have done, when you suspend it in the springs in the topplate, the slight vibration now transfered to your work bench will be gone/eliminated

cheers
henrik

[fermaleb]

thanks henrik!
I did the test of lifting it in the air with tweezers (tweezers with insulating rubber) and the noise (vibration) disappears.

now with the motor hanging it in the springs in the topplate:

Now I hear another noise (not the continuous one)
I think I hear something rubbing inside (use headphones to listen):

Could it be the Sinterbronze bearing? I already said that I saw it with some marks when I cleaned it.


Now another question arises: how should I hang the motor again? I don't understand how it was originally placed.
For the tests on the bench I worked with the motor leveled horizontally.

when putting it back in its place it is impossible to level it. The tip is too high. If I tighten all 3 nuts with the same tension, the tilt is greater.

The only thing I can think of would be to complement the spring of the tip, but I suppose that was not the case originally...





then...?

[aamodtasan]

Hi - the motor is not supposed to be level - provided you have the correct springs in the right places, it will be fine - https://www.lencoheaven.net/forum/index.php?topic=17383.0

member SPH sells new springs if yours are in bad shape

cheers
henrik

[Paul]

Hi Martin, the only part of the engine assembly that is supposed to be level is the theoretical line that runs along the length of the conical shaft where it makes contact with the idler wheel. That theoretical line is near the top of the shaft and because of the pronounced taper the nose of the shaft needs to be pointing upwards. A diagram would make it easier to understand.  

[fermaleb]

Thank you! It's understood very well.
It agrees with what I read lately in the forum.

this "theoretical line" would be the red dotted line and I should try to put it parallel to the turntable chassis (blue line)


I understand that this scheme would also apply to the view from above when aligning the idler.
The one on my l75 seems to be perfectly aligned to this imaginary line of the tapered axis and not to the center of the axis

[Paul]

Yes, exactly right Martin. I'd already made a very simple sketch before I saw your reply so I'll post it here anyway (although it essentially is the same as your diagram). 

[SteveM]

No need to complicate how to position the motor, although the explanations help understanding the system.
If the 6 springs are in their correct position and the 3 motor mount nuts are tightened fully, your motor should be in it's proper position.

Lencos are a different type of beast, subtly simple but simply ingenious.
I see some more questions about how this thing is supposed to work in your near future 
They're good questions.

Good luck with your Lenco and have fun!

[fermaleb]

Thanks Paul, your sketch is very good!

Thanks Steve, yes the motor stays in its perfect position on its own.
My doubts arose from a noise that was accentuated or disappeared depending on the inclination of the motor. This did not happen with the motor on the workbench where it was completely horizontal.
I disassembled the motor again, polished the sinterbronze (this time I did it right, turning them in a drill), cleaned them again and tried to refill them with oil, I think quite successfully.
When I started the engine again I had to look at it to see if it was turned (total silence)

Now start to battle with the idler wheel...