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TT Motor Hum- Help required


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I’ve got a hum coming from the pulley motor on my Kuzma Stogi S TT. It’s also slow to get up to speed. According to Kuzma the external power supply (which is connected to the pulley motor via an umbilical with DIN plug) may only be giving half output (it should output two phase sine wave). They suggest I measure AC output on Power supply DIN connector. Should be 100-130v between Pin 1&2 and pin 4&5 .

From photo attached... novice question perhaps - but which way are the DIN pins numbered - clockwise in numerical sequence? power supply gives you only half output. PS gives out two phase sine wave and if one output  is missing then can be e more vibration, longer time for platter to reach 33 rpm.
If electrical person can measure  PS output on DIN connectors- there should be AC voltage  around 100-130 V between pin 1&2  and 4&I would suspect that power supply gives you only half output. PS gives out two phase sine wave and if one output  is missing then can be e more vibration, longer time for platter to reach 33 rpm.
If electrical person can measure  PS output on DIN connectors- there should be AC voltage  around 100-130 V between pin 1&2  and 4&5.suspect that power supply gives you only half output. PS gives out two phase sine wave and if one output  is missing then can be e more vibration, longer time for platter to reach 33 rpm.
If electrical person can measure  PS output on DIN connectors- there should be AC voltage  around 100-130 V between pin 1&2  and 4&5.

016A1CA8-AF69-4260-A573-5E12012F5B4F.jpeg

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Hi There,

 

In the little circles next to the din pins, the end that plugs into that socket you show,  you will see a number. Its very faint , you may need a magnifier and some light to see into it. Use the rid slot as a guide to match pins with socket. If you have trouble seeing the numbers, google din plug, find one that matches yours with a diagram and pin numbers too help you.

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Tks dallyBoy,

Unfortunately no amount of light or magnification has yet shown the numbers and I've been down a few (and interesting) Internet rabbit holes looking for a Kuzma specific PS DIN - I did find plenty of 5 pin Mic DINs which are numbered 14253 clockwise (from the little square at top) plus plenty of other random things to throw me off the scent. So I'm hoping there's no difference between any standard 5 pin Mic DIN and my Kuzma power supply DIN.  Apologies if this all seems obvious to most but I've never really had any reason to look into DIN plugs previously (nor had any problem with my Power supply for that matter!).

 

Of course if anyone out there has a Kuzma TT with similar PS DIN and can confirm this that would be great!

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I had a look at mine but couldn't make out anything.  After reading your post again I am imagining a little one beside the square but not really...

 

From Kuzma Q and A:

 

"To test the PS check motor power. Remove the belt and try to slow down pulley rotation with three fingers, until rotation practically stops.  When it does stop it will vibrate.  Do not hold for more than 2 – 3 seconds.  If you feel very little resistance there could be one phase output failure which is giving less power to the motor.  If you rotate the pulley in the opposite direction and start the motor up and it continues rotating in the wrong direction, this indicates PS output failure."

Edited by Tim D
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Tks Tim, I’ll try that and let you know how I get on. I guess a PS output failure would require a new PS? I’ve had it for 10 years so it’s out of warranty and I’m a long way from any decent servicing.


BTW, this is what Franc Kuzma said.

 

“I would suspect that power supply gives you only half output. PS gives out two phase sine wave and if one output is missing then can be e more vibration, longer time for platter to reach 33 rpm.”

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One problem solved.... found the PIN numbers on the inside of the DIN cable, they aren’t in the DIN female plug....and the number sequence is different to the Mic DIN sequence .

3DCB4C19-65F5-47CD-8090-B54910A76D72.jpeg

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Well I tried the method described in Tim‘s post above....
-very little resistance when slowing down pulley. Vibration much the same. 
- also with pulley just running sub platter when I power the PS on and off, every so often it runs the platter backwards. Sometimes the PS won’t even rotate the sub platter without a nudge.

Something is failing... pulley motor or the PS is not outputting correctly.

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Good that you found the numbers. I did mean it was on the pin plug but anyway you found it.

 

Have you considered that the belt could need replacing after ten years, if it has not been replaced within the last 5 years it will need to be done. 

It would have stretched over time. 

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If it spins backwards it sounds like you have lost a phase. Any decent service tech specialising in hifi should be able to fix this. Try to get a circuit diagram from Kuzma, that will be a help.

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Thanks to all for useful comments and suggestions. As an update:

- the belt is 4 years old, swapped current and original belts back and forth with no change in the problem

- I opened up the PS, nothing obviously wrong, no signs of failure anywhere

- PS and pulley motor running ok once I nudge it up to speed (speed is then stable according to my Turntabulator RPM app)

- took the opportunity to give the whole TT a once over, topped up bearing oil, re-aligned cartridge, played with VTA, re-levelled the TT platform, swapped some power cords, re-positioned various cords and interconnects behind the other kit. All in all got rid of some hum and interference so apart from the motor vibration coming from pulley motor unit the TT is optimised. 

- I'll try and find a competent tech to look at the PS (not easy where I am curently living).

- also been in contact with Dutch company that makes the 

small motor in the pulley unit...just in case thats the problem

- and in the meantime, I"ll keep on spinning....

image.jpeg

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Not sure which London you are in but there is a Kuzma dealer in Melbourne and Sydney or if you are in Brisbane you can borrow my ps to test?

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Thanks for the kind offer Tim.....I'm currently outside of Aust and 4 hrs flight from the nearest Kuzma dealer but I have been in touch with Warwick in Melb about some options once I get back home...hopefully the PS will hold up until then.

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