How to straighten Armtube+Counterweight Stub connection of L75?

[Sasha]

Hello! I am new here and L75 is my first turnable.

My first quesion is how to straighten Armtube+Counterweight Stub connection of L75? Is it possible? I've removed Armtube+Counterweight Stub from Arm Pillar but both Armtube and Counterweight Stub don't have screws but some kind of other connection system which I don't know how to use. Please help.

[rfgumby]

Here's one older thread on that subject:

http://www.lencoheaven.net/forum/index.php?topic=3982.0

There's likely more , but this talks about the dental floss/super glue solution.   I remember someone actually rebuilt theirs somehow
and corrected the problem with that press fit union, but I can't recall exactly how they did it. 

[mfrench]

try to bend it straight by hand, and then fill the gap with tightly wound dental floss, with a whip finish.

scott beat me to it.

[Sasha]

Thank you for response.
OK, dental floss. ) Will try to find some kind of metal collar to fill the gap first. If not — dental floss.

[mediaman]

Welcome to Heaven

You may wish to share your real name in your signature like I and many of us here do. Also sharing your location in your profile sometimes makes it easier to help you.

Hope you enjoy your stay here, everyone is very helpful 

[mfrench]

Thank you for response.
OK, dental floss. ) Will try to find some kind of metal collar to fill the gap first. If not — dental floss.

The arm stub is decoupled from the arm wand. Dental floss still maintains that "decoupled" approach. Using a metal collar would work, but, would couple the stub and wand, making them one rigid component. Does this matter? ::shrugs::

[rfgumby]

The arm stub is decoupled from the arm wand. Dental floss still maintains that "decoupled" approach. Using a metal collar would work, but, would couple the stub and wand, making them one rigid component. Does this matter? ::shrugs::

I've read reports of people preferring coupled counterweights over decoupled (o-ring) types.  But I've also read contrary reports.

[Sasha]

Thank you, mediaman. I am from Moscow, Russia.

mfrench, it's a worthy addition! Thank you!

rfgumby, OK I will decide how is better in my system afterwards. For now I want to check every part and lubricate it.

Trying to disassemble Tonearm pillar. Roller bearing as I can see from below is a little rusty. Can't find spanner/wrench thin enough to fix Horizontal bearing race. Maybe will do a wrench from plywood or turbonit (paper-based laminate).

[AlexP68]

Sasha, it will be better if you find an experienced locksmith from tool department in the precise mechnical plant (or similar plant). He has to unpress (undrill) the rivets and cut the thread in two holes. Then it need to make (or find) two small screws and fix the new piano wire (with lengh 25 mm and diameter 1 mm as i remember).
After that your tonearm will be like new.
Good luck!
Alexey

[Sasha]

Alexey,
Are you from Russia?

He has to unpress (undrill) the rivets and cut the thread in two holes.

Do you mean brass pin inside two parts of arm?

Then it need to make (or find) two small screws and fix the new piano wire (with lengh 25 mm and diameter 1 mm as i remember).

"and fix the new piano wire"
Piano wire? Do you still mean that brass pin?

25 mm screws? Not too long?

[wer]

Way too long 

[martinhall]

Unless you realy HAVE to, don't be messing with the counterweight decoupling/stub! It is suposed to hang down a little with the weight of the counter ballance, that's NORMAL! It can break if you try to straighten it. If it is abnormaly bent, you will have a difficult time trying to rectify it. Nearly always the arm is damaged by NOT dismantling the deck before transit!! the platter coming loose and striking the other componants (it is heavy!). The counter weight bouncing on the arm's end? All should be dissembled before you move this deck or any like it (Mitchel Gallaxy's & etc)
The GL75 arm tube cannot be parted at the point of decoupling, it HAS to be decoupled because it is carried on rubber 'V' blocks and these would wear out quite quickly if the direct weight of the counter ballance were to be continualy exerted against these 'V' blocks when handling the arm. The decoupling also works with the rubber 'V' blocks and the suspension under the GL75p's plinth to prevent acoustic feed back occuring. With everything in good condition this works exceptionaly well. If you have a GL75 arm that has a damaged decoupling tube, shop around for a replacement, they aren't hard to find. You might try Technical & General advertised on the old Lenco Heaven site, I bought a pair of 'new' 'V' blocks from there, his prices are okay too.

[AlexP68]

Alexey,
Are you from Russia?
...

Sasha, you have a personal message.
Alexey

[Sasha]

martinhall, actually it was easy to make it straight with just hands. And I understand now that I must not make two parts one and solid. So, now I just interested how arm is constructed what is good to do and what is not. Thanks!

[jawaligt]

(...)

The GL75 arm tube cannot be parted at the point of decoupling, it HAS to be decoupled because it is carried on rubber 'V' blocks and these would wear out quite quickly if the direct weight of the counter ballance were to be continualy exerted against these 'V' blocks when handling the arm. The decoupling also works with the rubber 'V' blocks and the suspension under the GL75p's plinth to prevent acoustic feed back occuring. With everything in good condition this works exceptionaly well. If you have a GL75 arm that has a damaged decoupling tube, shop around for a replacement, they aren't hard to find. You might try Technical & General advertised on the old Lenco Heaven site, I bought a pair of 'new' 'V' blocks from there, his prices are okay too.

As always, your mileage may vary. I personally have had good results with coupling the counterweight more rigidly to the arm tube by using dental floss. Don't be afraid to experiment! Just make sure it's removable afterwards.

With regards to the design philosophy of the L75: I do think the arm deserves more credit than it usually gets. Still, we cannot assume the engineers did everything right. Take for instance the knife edge bearings which for all their elegance and sonic results weren't built to last due to decaying V-blocks. I don't believe the general Lenco user of the past would have taken the tonearm apart to check what's causing the weird sagging of his tonearm, let alone trying to fix it himself. On the other hand the motor and drive system turned out to be super-durable and the bearin isn't half bad either.

I think I've read somewhere that the decoupled counterweight stub was also used to compensate for footfall and other environmental vibrations, could that be right? Seems to me that would be less necessary in these days of ultra heavy plinths without any springs.