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

Showing 9 responses by elliottbnewcombjr

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

Damage:

UPS picked it up yesterday, plinth, tt, arm, cover. They are confirming damage before they pay the $1,000. insurance. I expect that to go well. The money may go back to the seller as he purchased the insurance on my behalf. Then, if he sends me the money back as a refund thru Paypal, hopefully two things will happen:

1. not charge the seller a fee to send me the money.
2. refund my original $46. paypal fee I paid to send the money to the seller.

I will check with Paypal before.
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Rubber Washer Repair.

My rubber washer was not factory, soooo ....
I never fully removed mine, soooo ...
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Removing two separate tubular pieces. (I should have taken pics).

a. the rear counterweight tube (easy). 

b. the shorter tubular fitting that my washer was pressed into (tricky). Note: this may not be required, it is possible I could have simply pulled the washer hard until it came out, but, I saw set screws and thought they were restraining it.

c. replacing thw rubber washer
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a. rear counterweight tube simply unscrews. it surprised me, I hesitated, but kept going, it came fully off. no real force needed, just confidence to keep turning.

now you have access to the rubber washer. 

My replacement washer had a shoulder/neck pressed into a short tube. I am calling that a short tubular fitting, part b.

The washer resisted coming out, so, I looked to see why. Perhaps I should have simply pulled harder, but I was concerned about ripping the washer apart.
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b. short tubular fitting. at the bottom surface, two very small allen-wrench set screws exist. You need to loosen both of them. now that fitting comes out of the main tube, washer still stuck into it.

c. replace the rubber washer?

When I saw the damage to the forward surface of that fitting, I stopped. Checked out the anti-skate, didn't like that either. Decided I was lucky UPS dropped it. Back together, back in the box.

I didn't pursue pulling the washer out. It may just be pressure fitted into a recess in that short fitting. 

If you tore the deteriorated washer out, I think you could put a simple plumber washer between the two parts, no real need for an exact match, no real need for one with a shoulder/neck to press into the fitting.

Home Depot, plumbing department. 
best-groove

If you see the innards, you realize the weakened rubber grommet is more critical than many think.

the link you posted is terrific, repeated below, and 2 links found within it

https://www.audiovintage.fr/leforum/viewtopic.php?t=55306

http://www.ne.jp/asahi/moto/jogging/audiowood.html

http://www.ne.jp/asahi/moto/jogging/audiowood.html#7045

the top link photos are the best I’ve seen, especially when fully disassembled to see the internal brass piece separately.

my 7082 was slightly different, however,

I now understand the design, which does TOTALLY isolate the rear assembly from everything forward of the pivot via a ’ two stepped’ rubber grommet:

’two stepped’ rubber grommet: like a 2 layer cake, the top layer (forward-invisible inside the tube when assembled) is a smaller diameter than the bottom layer (rear-visible separates the front and rear tubes when assembled).

It is the deterioration of the smaller unseen portion of the grommet that ’allows’ sag of the rear assembly. When seriously degraded (as mine was before the seller repaired it), it ’allows’ serious damage to metal parts.

The smaller diameter rubber layer gets pushed inside the forward tube, thus unseen when assembled. That is the TOTAL isolation from the front assembly. That portion, unseen, must be firm enough as it is carrying all the weight of the rear assembly.

The larger diameter rubber layer is the diameter of the tubes, thus visible, and simply keeps the tube faces apart from each other when assembled, like the white part of an Oreo cookie.

The larger diameter portion of the grommet also restricts forward movement of the internal rubber.

When the larger diameter portion is deteriorated, it also ’allows’ sag, however, it is the unseen rubber that is most important.

Assembly:

1. rubber grommet slides onto the brass fitting. The brass fitting has a thin flange at the face toward the pivot. That simply stops the stepped rubber piece from moving further forward.

2. Insert the brass piece/forward portion of the rubber grommet into the hole in the rear face of the pivot. Position it back far enough so the brass flange (now unseen) does not contact any internal pivot parts (in any position when the arm is moved.

3. Tighten the set screw.

4. The threaded shaft of the brass fitting faces rearward. The larger diameter portion of the rubber grommet is in place.

5. spin the entire counterweight assembly (it has internal threads) onto the threaded shaft. spin forward until it’s face is firm against the face of the rear face of the rubber grommet.

6. Fasten set screw.

Serious Internal Damage:

IF/When the interior unseen rubber grommet sufficiently deteriorates, the sag allows/moves the forward flange of the brass piece too far forward, actually making contact with metal within the pivot.

Half of my brass flange was missing, (fell out when seller repaired it). The remaining portion of the flange was ’mangled/misshapen-ed’. It must have been making seriously detrimental contact against internal pivot parts.

Before serious internal damage occurred, there had to have been minute contact, minutely effecting pivot movement, and both progressing speck by speck.

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You can buy an arm that has been repaired, and not see/know of any past or potential internal metal contact. Circumstances, curiosity, nothing to lose led to me discovering damage within. And, a set of tiny allen wrenches.

I suppose seller, when repairing the rubber, might have ’re-set’ the fitting rearward enough that no internal contact was occurring. All might have been happy ever after, but it was a disturbing sight for sure.

Anyone making the repair can re-set the brass piece to avoid internal metal contact.
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Mostly or Completely remove a damaged brass flange? I suppose so, however, it would have to be a one piece stepped grommet so the larger diameter layer kept the attached smaller diameter internal layer in place, unable to move too far forward. Careful positioning of both fitting and rubber in the pivot then locked with set screw.
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After seeing this, I would say, if your arm sags, fix it.




In the close up photo that shows the brass fitting, I noticed that:

the short chrome fitting that goes into the rear of the pivot: it has notches that must be to receive/retain the flange on the end of the brass piece.

During assembly the flange/notch positioning needs to be maintained until a set screw is tightened. Then all is well until the rubber deteriorates.

When the grommet deteriorates, the sag allows the brass flange to move forward out of those notches, larger amount of sag now possible,

and the brass flange can move forward enough to contact internal metal surfaces.
look at the photo where the brass piece is completely separate, no old rubber on it.

right of it, short chrome piece with notches to receive/retain the flange, and keep the brass piece from rotating after assembled.

the flange stays on. push the threaded end of the brass thru the short chrome piece. the flange and notches now mated.

put the short chrome piece into thew hole in the back of the pivot. verify no physical contact when arm is moved in all directions.

tighten set screw fixing short chrome piece.

slide the two layer grommet past the threads onto the brass piece, the smaller forward layer pressed into the short chrome piece, now invisible.

the second layer of the grommet is against the rear of the short chrome piece, visible, the part of the grommet that is always visible.

spin the entire rear counterweight assembly (it has internal threads) onto the threaded shaft of the brass piece.

rotate the assembly forward until it is snug to the rubber grommet.

tighten set screw.

assembly complete, entire rear assembly totally isolated from the front by the rubber grommet.

now, the balance and stylus force can be made using the movable weight collars. 

best-groove
409 posts
01-11-2020 4:59pm
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
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Not to be critical, however, to clarify for others, in the photo, the center piece is show reversed.

The small diameter threaded shaft is shown forward, it should face rearward.

That rear facing threaded shaft is what the entire counterweight assembly threads onto (counterweight assembly has internal threads). You spin the counterweight assembly forward till it is snug against the rubber grommet, and fasten a set screw. Then, balance and stylus force are achieved.
I just wanted others viewing that photo to realize, for any of these, the threads face the rear, and the counterweight screws onto it.
You can do this. Words, words, words, it’s not that hard, or precise.

prior link to good photos

https://www.audiovintage.fr/leforum/viewtopic.php?t=55306

You take it apart, remove the old rubber, install the new stepped rubber gasket (dimensions below), reassemble, no critical adjustments.

The hardest part is having/acquiring the tiny allen wrench to fit the 3 allen head set screws. That’s the only tool needed.

1. Disassembly:

A. Remove the rear counterweight shaft/assembly.

a1. loosen set screw on the counterweight shaft (probably on the bottom).

a2. unscrew the entire counterweight assembly. (counter clockwise from rear). It has internal threads, it simply spins off. Fear not, keep turning.

****Visible Now: old rubber on brass piece inside short chrome piece****

B. Remove the short chrome tube extending out of the rear of the pivot

b1. loosen two tiny allen-head set screws on the bottom of the pivot.

b2. pull short chrome piece out. (brass piece probably held in place by old rubber)

C. Remove all old rubber, pushing brass piece out of the short chrome piece.

***Notice: front of brass piece has tabs. front of short chrome tube has notches.***

Tabs in notches keeps the brass piece from spinning during re-assembly.

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2. Size of ’Stepped’ Rubber Gasket!

You need to take rear of arm apart to fix it, so take the short chrome piece and brass piece with you when going to the plumbing store/dept.

Described horizontally, facing cartridge.

2a. Front portion that becomes invisible when pushed onto the brass piece and inside the short chrome tube: 9mm outside diameter x 4mm long. (mine started out longer than 4mm and was cut by hand to 4mm long) (doesn’t have to be perfect length or perfect cut).

2b. Rear portion that remains visible, (ends up looking like a simple washer): 13mm outside diameter x 4mm long. (it could be a bit larger diameter but would visually exceed the counterweight tube’s diameter). (it could be only 3mm long. (Not more than 4mm long, you don’t want this portion of rubber to allow too much sag when re-assembled.

2c. inside diameter of gasket: sadly I forgot to measure it. it slides onto the brass piece. anyone know the diameter of the brass piece ___________ ? Take the brass piece with you.

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3. Re-Assembly

3a. insert brass piece into the short chrome tube.

3b. locate brass tabs in the tube’s notches

3c. push rubber gasket onto the brass piece inside the short chrome piece

You want the brass tabs to stay firmly in the notches before proceeding.

3d. Insert short chrome tube into the hole in the rear of the pivot.

***How far into the pivot?***

Far enough for the set screws to lock it in place, not too far to contact/interfere with arm/pivot movement.

3e. Tighten the two set screws. lightly snug, check full pivot motion, tighten firmly.

3f. Spin the counterweight assembly onto the brass threaded shaft.

*** Pull rearward while spinning on. Do not push the brass piece forward when doing this, you want the internal brass tabs to remain in the chrome tube’s notches so the brass piece cannot spin.

3g. Firmly snug the counterweight shaft to the rear face of the rubber gasket.

*** Now the counterweight has pulled everything together, has tightened the brass tabs into the notches, is holding itself firmly against the gasket***

3h. tighten the set screw preventing counterweight shaft movement.

Done.