VR T560 head weight/dashpot adjustment issue

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tragwag
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VR T560 head weight/dashpot adjustment issue

Post: # 48149Unread post tragwag
Tue Oct 17, 2017 3:49 pm

haven't seen this specific issue discussed so I made a new thread.
the numbers I have say to set the brass counterweight at 40 grams (while the stylus is touching the disc)
effective cutting weight should be 20 grams for old stylus, and 15 grams for new stylus.
on one machine it takes somewhere between 1 and 2 full turns to get the dashpot "engaging", and bring the total weight around 20 grams
on the new-to-me VR, I can turn the dashpot adjustment maybe 1/2 a turn, and then the stylus will leave the disc, but still be putting 30-40 grams of pressure on the little scale.

I've tried many head angle/height adjustments with the black knob to the left of the head, and nothing changes this.

Does anyone have more detailed info regarding the head weight/cutting pressure and how the dashpot should be setup?
Both my machines are second hand so it's likely I have very little info on the dashpot's regular range.

sorry if I threw in a bunch of weird terminology, again I'm a second hand user so I don't know the proper terms.
Let me know if you need clarification or translation.
making lathe cuts on a Presto 6N, HIFI stereo cuts on vinylrecorder
at Audio Geography Studios, Providence, RI USA
http://www.audiogeography.com

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The Shank
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Re: VR T560 head weight/dashpot adjustment issue

Post: # 48150Unread post The Shank
Tue Oct 17, 2017 3:53 pm

Check the spring around the dashpot, it starts to be maybe tired or not in his place. 45g to 50g for the counterweight. And check if the daspot is free of move on his brass cylinder
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tragwag
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Re: VR T560 head weight/dashpot adjustment issue

Post: # 48151Unread post tragwag
Tue Oct 17, 2017 4:11 pm

ah, I didn't even think about the spring! I'll go about looking for a new one. Definitely looks stretched.
making lathe cuts on a Presto 6N, HIFI stereo cuts on vinylrecorder
at Audio Geography Studios, Providence, RI USA
http://www.audiogeography.com

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tragwag
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Re: VR T560 head weight/dashpot adjustment issue

Post: # 48180Unread post tragwag
Sat Oct 21, 2017 12:33 pm

update: it seems the spring was applying too much upward force, making my counterbalance weight too light, and thus the dashpot adjustment bringing the stylus up almost immediately. I adjusted the spring so it was not applying any force with the head at rest, adjusted the counterbalance to the usual 40-45 grams, and now the dashpot adjustment can spin about 2-3 whole turns to get it to a solid 20 grams of force while cutting.

thanks everyone for the advice, I'll keep going on this.

If anyone has concrete "manual" type info on how the spring/dashpot, and all that are supposed to be adjusted I'd be grateful.
making lathe cuts on a Presto 6N, HIFI stereo cuts on vinylrecorder
at Audio Geography Studios, Providence, RI USA
http://www.audiogeography.com

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idecable
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Re: VR T560 head weight/dashpot adjustment issue

Post: # 48256Unread post idecable
Mon Oct 30, 2017 6:20 am

Assuming the spring of the damper holding correctly on both ends, is not compressed. Then adjust the back weight to make neutral position of the stylus at the same height of where the record is. Hold the cutter head with the scale while keeping it at that neutral height, *then turn the dial in on the damper, and measure desired stylus weight.

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tragwag
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Re: VR T560 head weight/dashpot adjustment issue

Post: # 48282Unread post tragwag
Tue Oct 31, 2017 11:23 am

yeah right on, I get that.
I think my problems stem from the fact that I can't tell if the spring is in the proper position.
both my machines are second hand so I have no standard to compare it to.
making lathe cuts on a Presto 6N, HIFI stereo cuts on vinylrecorder
at Audio Geography Studios, Providence, RI USA
http://www.audiogeography.com

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idecable
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Re: VR T560 head weight/dashpot adjustment issue

Post: # 48290Unread post idecable
Wed Nov 01, 2017 4:31 am

While holding the scale with stylus in neutral position, as soon as you start turning the dial for the damper, you can slowly see the grams building up.

*Before calibration for stylus neutral position, your damper has to be in a non compressed (or stretched) position. I dont think you should ever have it stetched, no point in that.

And, both metal ends that connects the spring together must have snuggle fit. There are lines that lets you lock the spring in.

Once you get that done, no more need to fiddle with the spring.

The *only thing left to do then is to introduce the stylus pressure while holding the scale, by turning the black dial on top of the damper and watching the spring compress and you get instant slow buildup of stylus weight, keep turning until you hit that 15g sweet spot.

And that's it. The spring is not meant to be plugged and unplugged all the time. You install the ends to the spring proprelly and *always use the dial at the top to operate it.

Backweight should always be used for neutral position calibration, and damper is always used for stylus pressure and suspension.

I don't think there is a need for stylus pressure caused by backweight imbalance.

Try it out :) I hope I'm explaining myself proprelly. It's okay to add me up and PM me, I'll be glad to assit where I can.

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