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 Post subject: Just about Teres'ed out
PostPosted: February 7th, 2021, 9:58 am 
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Having alot of problems lately with static build up zapping the motor controller on my Teres 340. I can get through one side fine, but flip it, and it flakes out halfway through the side. I have tried EVERYTHING, grounding the bearing, tonearm base, motor is already grounded. Tried different belts or cord drive. Also added a humidifier.

Looking at the fact that the turntable platter is non-conductive cocobolo, the pulley is anodized (non-conductive) aluminum, the static buildup has no where to go until enough kilovolts build up and it discharges. The turntable is basically a Van de Graff generator. I might as well rig up a "Jacob's Ladder" for effect.

At this point, I don't know that this will go away over time (after getting through heating season)

So, considering my options for vinyl playback, without spending a lot of money at this time (waiting to buy an end-game DAC), I see a few options to get records spinning again near term.

1. Instant gratification - Buy a new SL1200 Mk7, SL1500G, or SL1200 clone such as the Pioneer PLX-1000, Denon VL-12 Prime) to hold me until I get a better turntable. I have to deal with an arm that is marginal, but I have some tweeks I can do to the platter (a TTWeights copper mat), and can get better feet and KABUSA tonearm damping and rewireing. I am certain that this will ultimately be disappointing compared with what I have now, but who knows?

2. Vintage Direct Drive Motor Unit Project - Buy a used Denon DP75/DP80 (from Japan), Technics SP10 Mk2/Mk3, or JVC/Victor TT81/TT101. I would build a base capable mounting my 12" Jelco TK850L. The used Denon DP80 can be had for the price of a Technics SL1200 Mk7, i.e. under $1K. It may need to be recapped, bearing lubed and other minor work to restore it, but once restored should last the rest of my life problem free, and they reportedly sound very good. If I can get a JVC motor unit, these are also excellent (Goldmund used JVC motors). Technics SP10Mk3 gets expensive though.

3. Vintage Idler project - This is more than I want to spend now, since there is so much competition for units, and restoration can get expensive. The bargains are long gone.

4. Used Belt drive - Pick up a Thorens, Linn, AR, whatever, and restore and tweek it. Probably would need to buy an tonearm if it didn't come with one. I had a Thorens 35 years ago, and got a SOTA soon afterwards.

5. Do what I did with my DIY Teres, and ditch the Teres motor controller and find something more reliable. I ended up using a (no longer available) Maxon drive unit. Space is a problem, however.

6. Sit back and digitally Roon-out and hope climate improves. Really enjoying digital right now with Qobuz and my ripped collection (still a work in progress - gotta get moving on that!).

Anyway, any thoughts, observations, experience. I know Roscoe, Pete, and others have gone the vintage idler drive route. I have not heard much opinion on vintage direct drive motor units.

Sorry for the long post.

David


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PostPosted: February 7th, 2021, 10:22 am 
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I know this is sonically a terrible idea but to verify what’s going on I would somehow set up a grounded drain wire dragging against the platter and or the pulley to see if problem goes away


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PostPosted: February 7th, 2021, 11:37 am 
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Paul,

Good suggestion, though my challenge with this turntable is how to rig this up because of lack of a plinth. It makes the easy solutions difficult since you have to build a platform or support, though I might be able to rig up something with BluTack on the motor pod.

I just ordered some copper electrically conductive tape that I can wrap around the platter in contact with the belt I can then use a thin strip up and across the platter surface to the bearing shaft or have a grounded conductive brush in contact with it . I am not sure how well the tape would stick long term, the platter has a tung oil finish, so will have to degrease the area before applying the tape. This might do the trick, at least I will have the belt area grounded so that it should drain off any static. I can also use an electrically conductive mat to help drain off static. I have a graphite mat and copper mat, but they do not fit well due the fact the platter surface is not perfectly machined flat (it is made of wood). These work well on machined metal platters. Best would be something conductive and thin. Are there conductive paper, felt, or foam mats?

I will keep experimenting for now.

David


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PostPosted: February 7th, 2021, 11:45 am 
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Keep it simple
Just taped a grounded wire to the support beneath the plater and have the wire bent so that it just touches the underneath side of the platter. Let it drag along and suck up the nasty electrons
Pearl dose this with a piece of surgical tubing to dampen the platter from vibrations


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PostPosted: February 7th, 2021, 11:49 am 
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If I recall correctly, the Teres 340 is like the original Teres turntable which used feedback to control speed. There's an optical sensor that looks at a strobe pattern on the bottom of the platter and adjusts speed based on reading this strobe. Is that right?

If so, then the path for "zapping" the motor controller is probably through the sensor leads. You might try putting a zener diode on these leads and see if that would work to clamp the electrostatic charge from building up to the point where it glitches the motor drive.


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PostPosted: February 7th, 2021, 11:51 am 
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You can put part of the blame your platter pad. There are better choices out there that are reasonably conductive that do not allow the static charge to build.

As far as the controller is concerned -- that is entirely different issue. I think -- and this is entirely speculation -- that somehow any static charge build-up on the record is finding its way through the ground or the belt to the electronics.

Especially if the drive belt has carbon black content that could direct the charge right through the motor spindle to the drive motor.

Static charges can hit 5,000-volts or better and "march to the tune of their own drum."

Maybe -- just maybe -- aggressive spike protection surrounding the controller could take care of business. Especially the output feed to the drive motor. I presume your drive motor is DC powered. Maybe inserting an inductor in series with both motor drive feeds. A low DCR and high inductance inductor on each leg could possibly get the job done.

Or -- if you wish to go first class the following circuit could be your end-all:

https://electronics.stackexchange.com/q ... protection

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PostPosted: February 7th, 2021, 11:59 am 
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Another possibility instead of copper tape would be to try some lock lubricant, which is just very fine graphite dust. Conductive enough to prevent static buildup, but not enough to create ground loop problems. You could coat everything but the top of the platter, and then use something to conduct the static to ground. Something like this: https://www.amazon.com/TAC-01-Antistati ... B00B2AMSYS rigged up to run on the bottom or side of the platter and grounded, combined with the lock lube, (you might even try it w/o the lube first) ought to get rid of most of the static...

As for the DD Denon motors, be careful, some of those use a tape head like sensor and a magnetic tape strip on the inside of the platter to control speed, if the tape strip is coming off, you're pretty much screwed... That said, we used my DP-3000 based table at CAF one year, maybe the first year in the current hotel, and it worked out pretty well. You may need to not only re-cap the motor controller on one of these older units, you may also need to replace the transistors, as they tend to fail. Not hard, since they're all TO-92, but there are a few of them...

Roscoe

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Last edited by Roscoe Primrose on February 7th, 2021, 1:08 pm, edited 1 time in total.
typo


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PostPosted: February 7th, 2021, 12:28 pm 
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Roscoe Primrose wrote:
Another possibility instead of copper tape would be to try some lock lubricant, which is just very fine graphite dust. Conductive enough to prevent static buildup, but not enough to create ground loop problems. You could coat everything but the top of the platter, and then use something to conduct the static to ground. Something like this: https://www.amazon.com/TAC-01-Antistati ... B00B2AMSYS rigged up to run on the bottom or side of the platter and grounded, combined with the lock lube, (you might even try it w/o the lube first) ought to get rid of most of the static...

As for the DD Denon motors, be careful, some of those use a tape head like sensor and a magnetic tape strip on the inside of the platter to control speed, if the tape strip is coming off, you're pretty much screwed... That said, we used my DP-3000 based table at CAF one year, maybe the first year in the current hotel, and it worked out pretty well. You may need to no only re-cap the motor controller on one of these older units, you may also need to replace the transistors, as they tend to fail. Not hard, since they're all TO-92, but there are a few of them...

Roscoe

I use a Denon DP-59L DD TT and it runs beautifully -- especially the servo-controlled anti-skate and arm damping. If anyone out there has a complaint about the Denon DL-103 bass quality it can be much improved with arm damping.
Just like Roscoe pointed out -- the inside of the platter has the magnetic strip. What's different with the Denon is that it uses an AC motor and VFD control instead of a DC motor that is discredited because of cogging. I think some out there made a mountain out of a mole hill. Sure a DC motor cogs but the inertia of the heavy platter (fly wheel) eliminates that issue as evidenced by my experience with my Yamaha YP-D8 DD TT.


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PostPosted: February 7th, 2021, 12:41 pm 
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Do you have an ultrasonic humidifier you could put near the turntable?


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PostPosted: February 7th, 2021, 12:59 pm 
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I almost forgot. You could be the victim of a cold solder joint. Cold joints behave in strange and wonderful ways.

Cold joints were not much of a problem when PC boards were hand-soldered by techs trained to do the assembly work. But that has changed with automation and wave soldering.

I have been victimized by manufacturer cold joints -- and (embarrassingly) my own as well.

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