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Restoring and Improving A Thorens TD-124 MKII
Restoring and Improving A Thorens TD-124 MKII
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Old 5th December 2017, 05:44 PM   #2511
kleppermaster is offline kleppermaster
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Join Date: Jan 2012
Nigel, I would have to do some re-wireing to let the motor run 24/7 in the standby mode. The TD-124 cuts the power to the motor in the standby position.

I agree about the synchronous motor. The toothed belt may add some noise & belt slip isn't the problem. I've already ruled it out.

I really like the TD-124 drive system. When it works it works very well and very quiet. My previous table was a Denon DP-62r. It was a very nice table, but it's high tech design scared me. If anything major went wrong I couldn't fix it. That is why I traded to the TD-124
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Old 6th December 2017, 08:48 AM   #2512
AndrewT is offline AndrewT  Scotland
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Would it help start up and warm up to use a higher voltage, then reduce voltage to the fully warmed up after 20 minutes?

This could easily be done with an auto transformer.
125Vac to start up, 123Vac to warm up and 110Vac to 118Vac to run at chosen speed.
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Old 6th December 2017, 08:55 AM   #2513
nigel pearson is offline nigel pearson  United Kingdom
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I sent back the TD124 I borrowed to look at a filter system so now from memory. If the standby was just a transformer offering too low a voltage to overcome friction I think it could work. From memory the drive train is the same running or stopped. Not so the Garrard where it could get a flat spot. If so it could be a cheap solution with real merit. What happens here is the motor inductance and DC resistance are in series. If not the motor would take huge current. Even when not rotating the inductance is the dominant quality. At circa 80 Vrms ( 160 V rms UK ) I would imagine the turntable would stop rotating yet still draw a reduced current. I would guess when taken up to full voltage the warm up time would be about 3 minutes. If you say to +/- 0.1% it might be instant. I imagine 5 watts of heating would be available at 80 V. It would be interesting to know the DC resistance of the motor.

I know what you mean about the Denon. I bought JVC L3 and L5 mini DD for friends. I think they work better than a LP12 Ekos I was using ( DL110 ). Looking at all the details they are not what they look to be. JVC TT71 shares parts. Alas they need constant little fixes to keep them working. Mostly cleaning things. The rock solid images can make an LP12 sound like it's AR cousin. As someone said who had a LP12, slightly drunk. I would say no CD player I have heard puts the little JVC's to shame. No CD player makes me not go to bed. The JVC's go well past 2 in the morning. The arm design copes very well with warps, not plastic as it looks. The PU seems an AT95 type device. Some say JVC made the very best DD's. The Technics designs may well be JVC. My friend ex of JVC thinks so. He was involved with the Mobile Fidelity project. JVC X1 pioneered many aspects of modern pick ups. Diamond shape to track CD4 imformation well above 20 kHz. The half speed cutting to make it possible. Sad that some Mobile Fidelity cuts were not like the originals.
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Old 6th December 2017, 10:39 AM   #2514
nigel pearson is offline nigel pearson  United Kingdom
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Quote:
Originally Posted by AndrewT View Post
Would it help start up and warm up to use a higher voltage, then reduce voltage to the fully warmed up after 20 minutes?

This could easily be done with an auto transformer.
125Vac to start up, 123Vac to warm up and 110Vac to 118Vac to run at chosen speed.

Hi Andrew. That's an excellent idea. I built a very crude low cost auto using a boost transformer. If we take the USA mains to be 115Vrms nominal ( in the past 117V I am told ) we could risk 6Vrms boost. I would guess 7Vrms from a lightly loaded 20VA type. If the usual voltage is lower a 9Vrms type. I often have to build something like this to test an idea. I never had a problem. Auto transformers I have played with seem to be made this way. Keep an eye on it and if happpy buy a real one. I don't think you will have a problem. The buck version would be good for an early Garrard 301.

As I think is clear the transformer adds it's 6Vrms output to the real mains 115Vrms. If you get it wrong it will buck the voltage. If you have any doubts find someone who knows ( wise even if you think you do ). If you feed 115 Vrms directly into the 6Vrms side you will get fire. The fuse is about what I think should do the job. I suspect that is the best place for it. Another to the input 115V side would be wise. It " might " be 250 mAT. If you fuse at 200 mAT you might blow the fuse on start up. You might need 500 mAT. If you think you might feed it into the 6V side add a 500 mAT output fuse ( 3 x 500 mAT looks ideal, one in and one out in addition to my drawing, all on hot H side , as always unplug if changing fuses). Trial and error has always been so with fusing if at reasonable cost in a design ( if not using a starting timer and serries resistance ). Reduce the real risks is what engineers do. Often the fuse in an amplifier is vastly larger than the transformer rating. It is likely fault testing showed it was safe. I have drawn the colours roughly as I think they are. N is neutral and H is what we call live.

Click the image to open in full size.

Last edited by nigel pearson; 6th December 2017 at 10:43 AM.
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Old 6th December 2017, 12:09 PM   #2515
AndrewT is offline AndrewT  Scotland
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12VA dual 115Vac primary to dual 6vac secondaries, gives lots of choices.

input can be 115Vac alone and ignore both secondaries for 115Vac output.
Change to one 6Vac winding plus 115Vac as primary input. The output can be tapped from the input or from the 115Vac to give either 115Vac or 95% of 115 = 109Vac (this at a maximum current limit of ~1Aac).

Then one can have input to 115+6+6Vac to give an output from the top tapping (115Vac), or from second tapping for 95% = 109Vac, or third tapping for 90% = 104Vac. Again the lower tappings are limited to 1Aac.

Finer steps by buying a dual 5Vac, or a dual 3Vac.

An advantage to using dual secondaries + primary is reduced current (lower flux) and cooler autoformer temperatures. And also less wasted electricity (higher efficiency).

220/240Vac users get finer steps of 2.5% and 5% using the 12VA 230:dual 6Vac.
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Last edited by AndrewT; 6th December 2017 at 12:13 PM.
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Old 6th December 2017, 12:56 PM   #2516
nigel pearson is offline nigel pearson  United Kingdom
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Even something this small could work. As Andrew says we could do well with circa 5 or 10 volts ( 0-4.5 , 0-4.5 ). 105, 110, 115 , 120 , 125 Vrms. All for $5.

Vigortronix VTX-120-4206-4045 PCB Transformer 115V+115V 6VA 4.5V+4.5V | Rapid Online
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Old 7th December 2017, 09:15 AM   #2517
Jarle is offline Jarle  Norway
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Join Date: Jun 2012
I have done the following on my TD124:

Changed the bushings in the main bearing
Changed the bushings for idler wheel
Changed the motor bearings with new felts from Audiosilente.
New belt and motor decoupling springs from Hanze hifi
Everything is lubed with ISO46 compressor oil

The motor runs a bit on the warm side, but I suspect this will improve after some use.
Other than this, the table is running very silently, and I am very happy with the outcome of this.

I have ordered new armboards in plywood. I read the november issue of Stereophile about Swissonor TA10 tonearm. Here Mr Dudley is describing the "loose" mounting of the armboard to the turntable in the form of rubber grommets. He compared the fixed mounting to this and clearly prefered the compliant version.

Any comments on what is the prefered material for armboards?
Anybody tried to mount it "loose"?

I am goint to mount an old Ortofon SMG212 arm on my turntable.
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Old 7th December 2017, 09:47 AM   #2518
Jarle is offline Jarle  Norway
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This is information from the home page of Schopper:

The advantages over a normal wooden board is the efficient decoupling from the chassis. The material used is solid harder than wood. Thus, mechanical vibrations, which belong to the sound are not absorbed.
Soundwise the decoupled laminated board sounds louder than the wooden board and has a better bass reproduction. It lost no information.
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Old 7th December 2017, 12:45 PM   #2519
nigel pearson is offline nigel pearson  United Kingdom
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I found that with wood, I rather like MDF even though out of fashion. I use ply-MDF sandwitch. Ply alone sounds a bit brash to me, not talking fancy ply, Baltic birch I think. The motor being warm or even hot is normal. It might even be a good thing.
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Old 7th December 2017, 03:14 PM   #2520
AndrewT is offline AndrewT  Scotland
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Ply being stiff relative to weight and not lossy (Hi Q) will vibrate and probably at frequencies well into the audio range.
That may account for "brash"
Quote:
the decoupled laminated board sounds louder than the wooden board and has a better bass reproduction
This too sounds like vibrations in the audio range.

A well damped (Lo Q) flexible board might be OK.
A very stiff board, like carbon fibre sheet might be Hi Q. But a constrained layer arrangement with two thin carbon fibre sheets may perform very well.
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