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12" Fatboy unipivot , horizontal torque forces
#1
Hello,
After installing a rather light VDH Colibri on my 12" Fatboy unipivot with about 1.25gr VTF as per maker's recommendation , i noticed that when the stylus gets in the run out groove the tonearm automatically skids back  to a random position of the last track on the record. With cartridges which require higher VTF around 2.5gr this is not so evident.
It appears as if there is excessive antiskating caused by the  lemo wire . This happens even with the lemo wire disconnected fully from the junction box/disengaged and even when held straight upright. I experimented by twisting the wire 3 times fully counterclockwise and this stopped. However the twist of the cable is thus so pronounced that the whole balance of the tonearm is affected ...this is not normal. I also tested with Wally Skater and i got a huge reading (counted over 20 hashmarks) evidencing the existence of strong horizontal toque forces.
I read on this forum instructions by Harry to heat the wire with hair dryer to relax the internal forces. I tried that however with little effect. It is not very clear  how long i must heat and to what extent and at what distance from the cable though.
As i suspect the wire is twisted internally , would it be possible to remove cartridge , front grommet , disassemble the forward part of the tonearm from the rear part and turn the cable internally? Or would it be possible to turn the heatshrink tubing as it comes out from the top of the bearing housing??
Thank you  for any advice.
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#2
I’m currently running a VDH Colibri Stradivarius with a 12” FB gimbal with no issues. I do not use the lemo twist to set anti-skate as I find that is provides both an inconsistent force and a force that is not always inline with the horizontal plan (more of an issue with the Uni).

My recommendation would be to reset your lemo wire so that is has a little to no influence on lateral movement. To do this, set your vtf to O so that the arm/cartridge floats. Readdress your lemo wire so that it does not move the arm when floated over the middle of the record surface. You may need to heat the lemo wire (hair dryer on low) to relax the dialectic memory to achieve a neutral influence. Reset vtf to the manufacture’s maximum.

Play a record to see if this corrects the issue. If the issue is corrected, install the VPI mechanical anti-skate device and as a bonus, purchase and install the dual pivot option.
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#3
Hello Brf and thanks for your answer.
Maybe i did not make myself clear.The problem is that the lemo wire even if it is totally disconnected from the junction box is apparently so much twisted internally that creates a huge antiskating force that makes the tonearm skid outwards with a light cartrtidge like my VDH Grand Cru.To stop this i have to twist three times the lemo wire and this creates an unbalance. I have the dual pivot but this is not the solution. The "memory" of the dielectric has to be relaxed as you say. I tried to heat the wire with a hair dryer on low however with little result. I heated it for about 5 minutes holding the hair dryer from a distance of 10cm away and moving it up and down along its length.
Is there any other way to do it? Can the tonearm wire be removed somehow?
Thanks
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#4
Take off the arm and hold it upside down and let the lemo wire suspend freely. This should relieve any twisting energy. As an aside, there should be little to no rotational torque caused by the internal wire as it mainly resides on the longitudinal axis. Post a picture of your arm and lemo connection, perhaps we’re missing something.
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#5
I had to do this a few times to get the tension out myself. I put a hair dryer down then held the arm upside down with one hand. I drew my fingers of my other hand down the wires to the lemo as I pass it past the heat from the dryer. Sounds more complicated than it is. I did this once a day for two days and it removed the tension for me.
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#6
Hi bhjazz, Heating the cable more than once makes sense...i will try it out and report.
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#7
Video 
Hi again. I have tried twice to heat the cable but the problem still persists. It is slightly better (when measured with Wally Skater) but even with one counterclockwise twist of the cable as you see on the video i am still having problems . If i twist the cable three times to stop the excessive antiskating  the twist is so strong that unbalances the tonearm  to one side.
Thanks
password is 1234
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#8
(05-17-2022, 11:52 PM)Brf Wrote: My recommendation would be to reset your lemo wire so that is has a little to no influence on lateral movement. To do this, set your vtf to O so that the arm/cartridge floats. Readdress your lemo wire so that it does not move the arm when floated over the middle of the record surface.  You may need to heat the lemo wire (hair dryer on low) to relax the dialectic memory to achieve a neutral influence.  Reset vtf to the manufacture’s maximum. 

Were you able to float the arm with a neutral balance as described above?
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#9
Check and make sure the antiskate wire is not getting caught on something when your arm gets to end of record. I had exact same issue and the end of antiskate wire was getting caught and causing arm to bounce back. Never know:0)

Mike in Austin
Avenger MK1 Reference, Fatboy 12” Uni, Koetsu Rosewood Platinum, Eagle/Roadrunner, Audio Sensibility Cabling, ARC Phono Ref 2, ARC Ref 5SE, ARC Ref75, KimberKable 8TC, Vandersteen 3A Sig, Stillpoints under all
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#10
Brf. as you can see after heating the lemo wire,  i tried to float the tonearm in the middle of the record surface but it always returns to the beginning.
Mike, antiskate thread is not getting caught on anything.


 password:1234
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