Siemens micromaster 420 and turntable help

[Upfront]

I need a little help from those more clever than I.
I have a Garrard 301 and after reading about speed controllers, I purchased a Siemens MM420, programmed it (an event in itself!) and connected it. Once set, the speed is rock steady, very near to that of my SP10.
The problem is the noise it creates. This is where I need the clever help. The noise can be picked up through the cartridge. The closer the cart gets to the motor the louder (unbearable) the harsh buzzing. I connected a isolation transformer between the speed controller and the TT. This has taken most of the hum away but not all via the cartridge. It has also shown me how much noise it is putting back through the system. So I place another isolation transformer before the speed controller. But this hasn't obviously fixed the noise via the cartridge.
Any ideas how I can keep it quiet? I'd like to keep it, as the speed is unbelievably steady. But I can't handle the buzzing!

Thanks in advance for any help.

Linc

 

[Zen Mod]

you can try heavy choke , not isolation xformer

some boys at Lenco Heaven are having plenty of experience with mains controllers , especially with EMT decks

try to ask them there

 

[Upfront]

I did try asking there but no reply. Maybe a bump of the thread is needed. Choke is a good idea though! Thank you. Any idea of what size I would need? And I'd need one before and after again like I did with the isolation transformers?

 

[Zen Mod]

I believe one in between Micromaster and motor will suffice; for size - try biggest you have ....... maybe primary of big xformer , for test

I have intention to do the same , when I have time to connect Micromaster to my EMT 930 , but I'll need 3 of them

read this : http://www.lencoheaven.net/forum/in...lb2os5m58tjms3&topic=9241.msg237302#msg237302

maybe that's best place for your question

 

[Upfront]

Thanks for your help. I'll post there after work today.

 

[Upfront]

You need three chokes or three speed controllers?

 

[Zen Mod]

as far as I remember , Micromaster I have on shelf is having 3-phase output , exactly as needed for 930 motor .......

so , I meant on 3 chokes , I need to feed it


not case with your Garrard , though

 

[Upfront]

I thought that was what you meant. You are correct. I only use a single phase for the Garrard.

 

[Straight Tracker]

Hello Upfront

I only use a single phase for the Garrard.

I'm no electronics expert, but is it possible that the noise is caused by not using the other two phases?
Maybe you could connect a dummy load to the unused phases.

Sincerely,

Ralf

 

[Zen Mod]

not likely

as Upfront wrote

The closer the cart gets to the motor the louder (unbearable) the harsh buzzing.

culprit is clearly at phase feeding the motor

 

[Upfront]

I forgot to mention that although it's a 301 it is actually running a 401 motor an wiring harness including capacitors. Could a defective one of these cause an issue?

 

[kevinkr]

The output of the micromaster is not a sine wave, and probably has a lot of harmonics present particularly if square wave output is employed, in the case of half sine (not sine at all) this is also true.

Shielding the wiring may help, if possible installing a shield above the motor (ala TD-124) might also help. Using a choke and a capacitor to create an LPF on the output of the micromaster might help as well. Not sure how tolerant the micromaster output stages are to capacitance so proceed carefully if you try this - the choke in theory isolates the capacitance fairly well above the cutoff..

 

[carolus]

..... I did try asking there but no reply. ....

FYI.
c.f.r Manual Micromaster 420:
"The MICROMASTER 420s are a range of frequency inverters for controlling the speed of three phase AC motors. The various models available range from the 120 W single phase input to the 11 kW three phase input."

Only " three AC phase output" ....
(quid quid: type/concept Garard motor ?????)

My (home) experience:
I run my (very old lady) EMT930 three phase AC motor with a inverter "Mitsubishi S500" (output three AC phase)..... & with (hi-fi) satisfaction (and with Ortofon MC).
(this is not a product placement).

 

[volken]

I forgot to mention that although it's a 301 it is actually running a 401 motor an wiring harness including capacitors. Could a defective one of these cause an issue?

All the inverters creatate a lot of noise the one more then the other.
Thats the main problem with these.
I use a Siemens 420 on a EMT 930 to compare it with a analog one I build . Best you can do is shielding the cable to the motor and keep the controller away from the table.

Volken

 

[Upfront]

Thanks guys, maybe it's time to sell it off and put the money towards the Lenco Heven speed controller.