Bench Testing a Thorens TD124 Motor - diyAudio
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Old 18th January 2013, 04:22 PM   #1
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Default Bench Testing a Thorens TD124 Motor

Guys,

I bought a TD124 recently, and I'm restoring/rebuilding it on a budget. I rebuilt the motor a few days ago, and I'm hoping to run it in and seat the bearings properly. Issue is, I don't have a variac or very much electrical knowledge. I got some thoughts from Audiokarma, and the consensus was that I could do it simply by soldering a lamp cord to the appropriate leads from the motor and plugging that in.

I have read this thread on how to do it:
トーレンス THORENS model TD 124

and the motor is back together, but I have a question. Based on the TD124 Motor and the thread above, it seems that I should connect the two black leads to each other, and connect one red lead to the positive wire from the lamp cord, and one red lead to the negative lead. Then just plug it in?

Thanks
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Old 18th January 2013, 04:29 PM   #2
kevinkr is offline kevinkr  United States
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Yes, this should be fine.. I do recommend you wire a 40W/120V incandescent lamp in series to protect the motor against miswiring initially.

Big TD-124 thread here: Restoring and Improving A Thorens TD-124 MKII
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Old 18th January 2013, 04:43 PM   #3
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Kevin,

Thanks for the response. Frankly, I'm not even sure how to wire a bulb in series here.

Have read parts of the big DIY 124 thread, but have not gone through all 150 pages. Did read the motor section, and he references testing the motor, but does not break it down to the point where a luddite like me can understand exactly how to do it.
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Old 18th January 2013, 04:52 PM   #4
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There's quite a lot of motor related stuff in the thread, and I've replied to several others regarding motor issues.

Purchase a ceramic lamp socket, connect one side of lamp socket to AC line cord, other side to one of the motor's red leads, connect the other side of the AC line cord directly to the other red motor lead. Make sure you insulate everything with electrical tape!
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Old 18th January 2013, 05:01 PM   #5
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Had not realized the "he" was you! Glad to have your ear on this. I referenced your page 60 along with a few others for the "how to" on the rebuild, along with baking out the bearings, re-impregnating them, etc. etc. - I just didn't see a "plug this wire into here, plug that wire into there" to break in and adjust the motor.

Will go do so now, and let you know the results.

Thanks again.
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Old 18th January 2013, 05:05 PM   #6
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As you proceed you would be most welcome to post pictures and comments to the main thread about your experiences.. I get a kick out of working on these tables and own two plus a parts unit..

Have rebuilt a number for others as well, still learning!
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Old 18th January 2013, 06:11 PM   #7
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Well, the lamp cord (i went to goodwill and bought a lamp with a switched cord) appears to be working perfectly. Per some feedback from a guy on audiokarma, I started with the green wires, and will move to yellow and then black, as a veritable built-in variac. She's coming along nicely. I'll keep her going for a while, and see about adjustments shortly.

Click the image to open in full size.
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Last edited by jdgordon; 18th January 2013 at 06:18 PM.
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Old 20th January 2013, 08:53 PM   #8
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Sounds good, make sure the felts are quite soaked with oil..
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Old 21st January 2013, 03:14 AM   #9
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Well, I got it perfectly silent out of the table - there was still a hum when using a stethoscope on the motor housing.

However, when I put it back in the deck and put the belt on, and fired it up, there's a distinctly audible metal-on-metal hiss. I've read that it's louder under load, and that it's louder at the beginning of the break-in cycle, but should I be hearing this? Is it a question of tapping the motor housing to get the bearings to align a bit, or should I tear it down to see what's going on?

Thanks again.
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Old 21st January 2013, 04:48 PM   #10
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Not sure I understand exactly what you mean, but no the TD-124 drivetrain is not, nor ever will be silent. Even in tip top shape it will be audible from a short distance away depending on room noise levels and your hearing acuity.

It is extremely important to make sure all running surfaces are smooth and clean and I recommend lightly polishing the motor pulley and stepped pulley running surfaces.

The type of belt employed and its initial tension play a big role in the noise levels generated. The Schopper belt (prohibitive) really is the best belt I have found so far, followed by at least some instances of the Hollywood Florida belt I have mentioned in my thread.

Applying real talcum powder (generic foot powder with 100% talc) to the belt prior to installation will help as will running for some number of hours.

Things will quiet down quite a bit as the belt stretches.

Make sure that you have properly relubricated the intermediate stepped pulley bearing (bearings) before running for an appreciable length of time. Not knowing the vintage of your table I can't advise further. (Does it have the single bronze bearing in the pulley itself or a pair of bearings in the chassis?)
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