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Spider27

Tonearm Lifter Hanging....

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Posted (edited)

Hello,

 

I have Jelco tonearm that works great except cueing mechanism or arm lifter. When lever drops, the horizontal level/plate drops a bit then hang there a few seconds then slowly drop all the way down.

That hang at the start is annoying and I took it apart and re-lubricated with pure silicone oil 300,000 cst which should have enough viscosity. When I push it down and up a few times then it works smoothly. However, it happens whenever I leave it for awhile and drop the arm again.

 

My initial thought was oil is dirty or old so need to be re-lubricated but it is not the case if I understand correctly.

 

Has anyone have re-lubricated the tonearm lifter successfully before? If so, could you please share one or two tips? :) 

 

Here is the shot of tonearm lifter.

 

 

jelco tonearm lifter opened.jpg

Edited by Spider27

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Posted (edited)

Is there perhaps a burr or something causing the hang in descent?

Distortion of the tube or piston?

Some residue or rough spot?

 

Can you assemble the piston at a different rotation into the tube? Maybe it's better 180 degrees turned?

 

I'd probably give the contact surfaces a polish with some 1000 or higher grit Wet'N'Dry abrasive paper.

Edited by pwstereo

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Tis the season for cue arm damping issues it would seem

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38 minutes ago, pwstereo said:

Is there perhaps a burr or something causing the hang in descent?

Distortion of the tube or piston?

Some residue or rough spot?

 

Can you assemble the piston at a different rotation into the tube? Maybe it's better 180 degrees turned?

 

I'd probably give the contact surfaces a polish with some 1000 or higher grit Wet'N'Dry abrasive paper.

Thank you for the suggestion. I will give it a go later today and report back. 👍

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What would have caused in to get scratched/dinged enough to need polishing? If it really needed polishing I'd be starting only with a cloth or piece of leather. The fit of the slider and tube would seem to be fairly critical. Even the surface texture might be important.

 

If it's just wear then the 180° turn sounds promising.

 

If it only hangs for a second or two that's just enough time to sit back down.

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23 minutes ago, GregWormald said:

What would have caused in to get scratched/dinged enough to need polishing?

Maybe a previous inexpert attempt at disassembly/repair (not suggesting by the OP)?

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I cleaned and every bit and relubricated and tried.... And, it does not come down to the bottom but hang at the top..

 

when I move the lever up and down 8~9 times then it works and comes down smoothly every time after that.

 

However, if I leave it for an hour or so and try again, it happens again.

 

My guess is that the viscosity may be too high (300,000 cst) or inner wall of barrel needs to be lubricated by the lubricated cylinder moving up and down so it goes down without hang?

 

Not sure if this is norm for Jelco tonearm...

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Left it for an hour and just tested it again and it does not hang this time. Might need to monitor closely to make sure it is definitely working.

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56 minutes ago, Spider27 said:

Left it for an hour and just tested it again and it does not hang this time. Might need to monitor closely to make sure it is definitely working.

No... I am wrong. I tried again and it hang on top and does not come down. After 8 times of moving the lever up and down, it works smoothly again.  🤔

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Posted (edited)

Cleaned off cylinder and just applied a tiny amount of this thick silicone fluid to the cylinder wall of cueing mechanism and it is better.  The quantity of oil must affect the performance of cueing mechanism and too much is worse in this case. 

Edited by Spider27

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Just a smidge is usually all that is needed  -  after a clean of course.

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Just now, Grumpy said:

Just a smidge is usually all that is needed  -  after a clean of course.

Yep. I continue testing by leaving it idle for half an hour and try again and it is now much better than original status. A drop or two to very thin coat on inner wall of cylinder seem all needed.

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Hey Jim, 

if the clearance is very tight anything beyond a very fine film would be problematic. 

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13 minutes ago, thejt said:

Hey Jim, 

if the clearance is very tight anything beyond a very fine film would be problematic. 

Hello, Yes, it looks like it is the case here. 😅

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If it was an engine I'd say piston slap. As a joke
 

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From cold start, it is now 3 up & downing the lever, it works smoothly. Definitely improvement from previous 8 times up and down to make it work. Still bit of work to be done to make it work every time without pre-up& down movement.

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Maybe just clean all the silicon lube out and try a light machine oil.

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3 hours ago, pwstereo said:

Maybe just clean all the silicon lube out and try a light machine oil.

I tried it first thing before applying silicon lube and it was no no... It drop it super fast and also making funny fart sound. Silicon oil is the one for sure but I feel that it is the quantity that counts unless I miss something else. 

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Maybe a lighter weight of silicon damping oil then.

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10 minutes ago, pwstereo said:

Maybe a lighter weight of silicon damping oil then.

That might be the solution. If I cannot make it work with current oil, might get lighter one to try. I somehow could not find high viscosity silicon oil domestically hence ordered it overseas and it took very long time to arrive.

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9 minutes ago, Spider27 said:

... ordered it overseas and it took very long time to arrive.

That's a painful reality for so many low volume specialty things in AU.

Good luck with your quest.

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Third time cleaning off cylinder and it now works every time (Will monitor closely but it looks like works now every time). 

I am just surprised how little oil it really requires to make it right. 

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3 hours ago, Spider27 said:

Third time cleaning off cylinder and it now works every time (Will monitor closely but it looks like works now every time). 

I am just surprised how little oil it really requires to make it right. 

YEP.

BTW  the 300,000 'oil' can be found at some RC car hobby shops  -  used in the diff gears.

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