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Victor UA-7082 Arm, Rubber Washer at Rear Counterweight Tube: Sag/Repair/Fitting Damage.

Victor UA-7082 Arm, Rubber Washer at Rear Counterweight Tube: Sag/Repair/Fitting Damage.
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The Large Plinth with UA-7082 I bought arrived, the plinth, legs, dust cover seriously damaged. Insured, at UPS for damage claim now.

The arm, before I bought it, the counter weight tube was sagging (very typical it seems), because the rubber washer between the main tube and the rear counterweight tube had deteriorated (the typical age related problem).

I pointed it out to seller, he fixed it, posted new photos, I bought it.

The arm arrived undamaged, however, it was going back, and, perhaps I will buy one in the future with bad rubber, soooo, I decided to see how he fixed it.

I’m no engineer, this is my attempt to clarify the rubber repair for myself and others. Lot of words to attempt clarity, it’s not that complicated.

1. the 7082 (presumably 7045) rear tube and counterweight are not totally isolated from the arm by a tubular layer of rubber like my SME 3009 was. (I repaired 3009 with factory rubber tube from SME when I first got it).

2. The 7082 rear tube is threaded, It threads into the back of a fitting on the end of the main arm, just behind the pivot. Not tight machine threads, so minor movement can occur. That is a semi-solid, not totally isolated connection. If the rubber washer is weak, these loose threads allow sag to occur. Perhaps the threaded shaft gets bent down also.

3. You thread/snug that rear tube forward against the rubber washer. The thickness of the washer is therefore not critical (except too thin). The density of the rubber needs to be firm enough to keep the rear tube from sagging, but not too hard, so it can do it’s job: dampening vibrations traveling down/back up the tube, isolating counterweight .... engineers can clarify this design function.

4. Washer Shape. Factory ____? This one: It did not slip off the front tube as I expected a simple washer would. It had an integral smaller diameter ’shoulder’ or ’neck’ that projected forward into the rear tube fitting. There are two tiny allen-head set screws at the bottom of the fitting. I loosened them and a short piece of tube came out, less than an inch long, rubber washer at the rear end.

5. Front face of the small fitting with the washer has/had a brass faced plate, curved. This one was damaged, part missing, part ’mangled’. My guess, it was set too tightly to the face of the arm shaft, someone messed with it, who knows ....

6. The point is, unless I took it apart, it looked fixed, you would definitely choose this over one with deteriorated rubber, sagging rear tube. But it had invisible damage. No way to know if buying used. Or know after you received it. I think this is probably a very rare instance, just mentioning it, perhaps someone knows something about it _____ ?

7. Effect performance??? Many have said they have weak rubber washers/sagging rear tubes: so what, plays great. The fitting: internal damaged brass face could be carefully reassembled, making sure no contact with anything.

8. Anti-Skate. I don’t like it, especially used. The plastic cap lifted off to reveal a spring coiled around the shaft (cap’s tiny set screws too loose?). Turning the top dial compresses the spring, step-less progressive resistance to the rotation of the arm shaft, great  ... Counter-acts inward force when playing.

Perhaps I would be confident with new from factory, but, there is no way I would be confident with this one, or any used one. Where is zero? Prior in-appropriate revolutions? Weakened spring?

I like dangling string counterweight with many small 1/4 gram notches like the SME and others. One thing I did not like about my 3009 Anti-Skate was the age and brittleness of the plastic line, but it always tested accurate in use.

9. Actual anti-skate. Listening, test record, final set of anti-skate is best. But, when changing cartridges, Stereo to Mono, Shibata to Elliptical: quickly adding or reducing tracking force, then a quick anti-skate corresponding change ..... no listening test, trust the incremental changes from prior proven setting. I feel more confident moving the string to the next notch than adjusting a spring.

Hope this is helpful, perhaps others can clarify anything I got wrong.

Elliott


elliottbnewcombjr
elliottbnewcombjr OP
5,112 posts
 
btw,

found another large plinth dual arm tt81, bought it, seller assures protection.

https://www.canuckaudiomart.com/details/649579421-victor-jvc-tt-81-high-quality-quartz-lock-turntable-with-fidelity-research-tonearm-reduced/

I probably will move it's Fidelity Research arm to the rear for Mono, and install my newly acquired Lustre GST-801 as main arm for Stereo and cartridge swapping. It arrived looking gorgeous.

That will be two 9" arms, not my original goal of one 12" arm, but, thankfully I learned here the cartridge compliance gets more complicated with longer heavier mass arms, so, I'm ambivalent.
lewm
12,456 posts
 
I have had my UA7045 apart at the counter-weight, so I can sort of follow your description of what you found, but I'm not totally clear. In my case, I could not get the mating metal pieces apart, which you need to do in order to replace the rubber, and I ultimately decided not to keep at it until I understand better how they come apart without applying brute force. Question: how do you know that what you see inside is not original, since to my knowledge there exist no factory drawings or even photos on line? Maybe Chakster could enlighten you and me and others.  My other question: You are sending this UA7082 back to the seller, presumably for refund? 
totem395
390 posts
 
The above Victor series may have been 
one of the last mass produced arms to incorporate the traditional 
rubber isolation between the pivot and rear stub.

In the early day's of audio most higher end arms incorporated
this design including the SME series 1 and original Ortofon broadcast arms mono and stereo.




 


best-groove's avatar
best-groove
831 posts
 
I repaired and replaced the Victor arm rubber a short time ago, no problem if you are practical with DIY

https://i.postimg.cc/JhGB0fL8/DSCN5962-thumb-jpg-da81b9ff50d69a0d02549b0dc19fd7f4.jpg
lewm
12,456 posts
 
Totem, Many more modern tonearms also use some method or other to decouple the counter-weight from the pivot.  The idea is a good one, from an engineering standpoint. Fidelity Research FR64S and 66S have this feature, among tonearms of a similar vintage to the Victor tonearms.  Triplanar has it too. What started this thread about the Victor tonearms is more about whether and by how much the counterweight can be permitted to sag, due to wearing of the rubber joint or to its deterioration related to age.
Best-groove, I went to your URL, and I think you provided it once before. The problem is that it shows your tonearm and CW already separated.  That doesn't help much if the joint won't come apart in the first place. I'm referring to the metal to metal joint that gets exposed when you open up the juncture.  Do you have any additional photos of the step by step process? Thanks.
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