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Marantz TT-15S1 spinning to fast after moving to EU

jviss said:
In the sales literature Marantz says this uses an asynchronous motor:
Click to expand...

Most likely a bug, as in the spec sections of both the multi-language user manual and the service manual for the variants /N1M and /T1M it says "synchrnous motor". And if you look at the OP's pic of the underside of the motor in post #19, you can clearly see the two speeds 250 rpm for 50 Hz and 300 rpm for 60 Hz, so it would seem highly unlikely, that the motor wouldn't be 24-pole synchronous.

Greetings from Munich!

Manfred / lini
 
Disclaimer: I could be totally wrong about all of this. I'm just putting this case together from information available in the Marantz literature, and the symptoms described here. It's been 40+ years since my motor course in engineering school! I would ahve selected a synchronous motor was I designing a TT, but Marantz says this one's asynchronous, so there you go. :)
 
lini said:
Most likely a bug, as in the spec sections of both the multi-language user manual and the service manual for the variants /N1M and /T1M it says "synchrnous motor". And if you look at the OP's pic of the underside of the motor in post #19, you can clearly see the two speeds 250 rpm for 50 Hz and 300 rpm for 60 Hz, so it would seem highly unlikely, that the motor wouldn't be 24-pole synchronous.

Greetings from Munich!

Manfred / lini
Click to expand...
Oh, good point! I'll re-run numbers with those speeds and see what I come up with. Thanks!

But, I don't see "synchronous" in any of the Marantz manuals I have. Can you provide a link?

I had run it out with a 24 pole motor, at those speeds, of course, and assuming that the OP's assertion that the platter was precisely 296.86mm in diameter, the motor pulley diameters for 33 1/3 RPM at 50 and 60Hz would have to be 39.6 and 33mm, respectively. Given that's the effective diameter, not the diameter of the flange, etc., so it could well be so. The difference between these diameters and the quoted 44 and 37 is the same, 4mm, so that could well be the outside of the flange diameter of the pulleys, if there is a flange.

UPDATE: the above has a mistake, I was wrong about which pulley diameter to use in the calculations. The larger step on the pulley, the one that's dimensioned in the illustration, is for 45RPM operation. I mistakenly used it for 33 1/3 RPM calculations.

UPDATE 2: not so sure it was a mistake; given the motor of which the OP supplied a picture, which is certainly a 24 pole motor, and runs at 300 and 250 RPM at 60 and 50Hz, respectively, and given the platter diameter is precisely 296.86mm, the required pulley diameters are,
For 45RPM and 33.33RPM:
60Hz: 44.55mm and 33mm (yes, that's 32, 9967mm!)
50Hz: 53.46mm and 39.6mm

So, it seems the illustration may be imprecise, in that it indicates the large pulley step diameter, but quotes the small step dimension. Make sense?

Screenshot 2024-02-15 at 9.45.16 PM.png

In any event, it's not the motor voltage, it's the pulleys! :)
 
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@malotru007 do you have a caliper? Can you please precisely measure the diameter of both steps of the motor pulleys you have? You said you have two, but they are the same, that's fine. Both step sizes would help me. Measure at the "central slot" as per the illustration above.

I ask because I checked my math, and came up with the following:

Given the 110VAC 50/60Hz motor running at 250/300RPM, per your pic earlier in the thread, and your specification of the platter diameter as 296.86mm, these are the effective motor pulley diameters required for proper operation at 45 and 33 1/3 RPM:

60Hz: (large step/small step) 44.529/32.98mm
50Hz: (large step/small step) 53.435/39.58mm

Thanks,

jv
 
Given my previous post, let's just say we pretend you're in Japan when you're at the output of your step-down transformer. I know, it's not 110V, it's most likely going to be 115V, since Italy is 230V and the transformer is probably a 2:1 step down. But, the higher voltage won't hurt that motor, and won't make is spin any faster or slower.

(I checked, and a European motor for this table is over $500 USD.)

With the transformer, there's a pulley that will operate this at the correct speeds. I don't think you have it, I suspect, you have two US spec pulleys.
 
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ralphfcooke said:
JV, when you did your calculations did you take into account the 2mm diameter of the round belt that's used to drive the platter?
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No. How would one account for that? Or why would one account for that? Surely it's only the contact surface of the belt on the pulley and platter that matter. The belt could be six inches in diameter and it wouldn't affect the speed, no?

If you disagree I'd like to hear the theory.
 
O.K., now I'd like to ask the mother of all stupid questions: @malotru007 , have you contacted Marantz customer support?

Marantz Customer Support​


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You can contact our Support team via chat, phone or by email from our Support site. https://support.marantz.com

To minimize any wait times, our Chat service option is preferred. Chat is avaiable Monday - Friday 10 AM - 7 PM and Sat 10 AM to 6 PM EST. Our phone Support is available Monday - Friday 9 AM to 9 PM EST.


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jviss said:
I ask because I checked my math, and came up with the following: (...)
Click to expand...

Might not work out like that, 'cause your calculation seems to be based on n(motor) * d(motor) = n(platter) * d(platter) rather than n(motor) * (d(motor) + thickness of belt) = n(platter) * (d(platter + thickness of belt). The latter formula is based on the assumption, that the true linear speed is found roundabout at the middle of the belt, as its outside is streched, while its inside is compressed, when going around the pulleys. And of course even with that formula it might not work out 100 %, as possible belt slip isn't yet considered.

Greetings from Munich!

Manfred / lini
 
I haven't tested it with round belts, but a lot of testing has been done with flat belts and it's 'proven' that belt thickness affects pulley ratio; a thicker
belt causes the platter to run faster. As lini said above it's 'normal' to add the thickness of the belt to the diameter of both the motor and platter when
carrying out the calculations.
 
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lini said:
Might not work out like that, 'cause your calculation seems to be based on n(motor) * d(motor) = n(platter) * d(platter) rather than n(motor) * (d(motor) + thickness of belt) = n(platter) * (d(platter + thickness of belt). The latter formula is based on the assumption, that the true linear speed is found roundabout at the middle of the belt, as its outside is streched, while its inside is compressed, when going around the pulleys. And of course even with that formula it might not work out 100 %, as possible belt slip isn't yet considered.

Greetings from Munich!

Manfred / lini
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Thanks, Manfred, but I don't think that's so. The only force acting upon the pulley and platter is the friction of the contact surface of the belt.

Let's assume no slip of this belt.

Then, try this. Think of a theoretical belt that's 2mm thick, and 1km wide, where the 2mm part is what's contacting the pulley and platter (hereinafter referred to collectively as 'pulleys'). The belt is magical, in that it's massless, and of such a material that it can actually turn around the pulleys, and not sag, and not absorb any of the motor power. So, should we calculate the speed ratio based on the center of the belt, 0.5km out, or at the surface of the pulleys?

Similarly, do you think changing from a 2mm diameter round section belt to a 3mm round section belt will change the speed ration?

I don't think so.
 
ralphfcooke said:
it's 'normal' to add the thickness of the belt to the diameter of both the motor and platter when
carrying out the calculations.
Click to expand...
The total thickness of the belt, or 1/2 the thickness of the belt?

Any difference, flat belt to round belt?
 
jviss said:
O.K., now I'd like to ask the mother of all stupid questions: @malotru007 , have you contacted Marantz customer support?

Marantz Customer Support​


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EMAIL THIS PAGE
How do I contact Marantz Customer Support?

You can contact our Support team via chat, phone or by email from our Support site. https://support.marantz.com

To minimize any wait times, our Chat service option is preferred. Chat is avaiable Monday - Friday 10 AM - 7 PM and Sat 10 AM to 6 PM EST. Our phone Support is available Monday - Friday 9 AM to 9 PM EST.


Customer Care Line​

1-800-654-6633

Monday to Friday: 9:00am to 9:00pm.
Saturday: 10:00am to 6:00pm.
All hours are Eastern Standard Time
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Not stupid at all. Great minds think alike or you might call it synchronicity... When you IM me this morning, I thought the only way to get to the bottom of this, was to contact them. I sent an email and I'm awaiting a response.

As far as the caliper, no but look at post #31, sqlsavior measured it and he has a US version bought at the same store I did (MusicDirect).
 
ralphfcooke said:
I haven't tested it with round belts, but a lot of testing has been done with flat belts and it's 'proven' that belt thickness affects pulley ratio; a thicker
belt causes the platter to run faster. As lini said above it's 'normal' to add the thickness of the belt to the diameter of both the motor and platter when
carrying out the calculations.
Click to expand...
I don't buy it. I'd have to see a reference. The only thing I can imagine would result in that is if the thickness of the belt affected the effective diameter of the driving or driven pulley.

UPDATE: O.K., maybe so! I did some searching. But how much are we talking about? And how does this affect the current situation, with off-the-shelf parts and belts?
 
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The belt has a neutral line somewhere between inside and outside faces; inside that line it compresses around curves and outside it stretches. The effective diameters of the pulleys are the actual diameter plus 2 times the distance between the neutral line and the inside face of the belt.
 
absolon said:
The belt has a neutral line somewhere between inside and outside faces; inside that line it compresses around curves and outside it stretches. The effective diameters of the pulleys are the actual diameter plus 2 times the distance between the neutral line and the inside face of the belt.
Click to expand...
I'd love to see a scientific paper on this topic!
 
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