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Delboy 4th June 2003 03:54 PM

Turntable Hum
 
I have noticed recently that my cartridge is picking up hum the closer it gets to the spindle, i.e. it seems ot be coming from the motor which is an a.c. type located to the rear left of the tt. Does anyone have any ideas about how to cure this problem?

Netlist 4th June 2003 07:58 PM

Hi, Delboy

What brand is it?
Does the hum increase when you move the arm in the up-position towards the spindle, or only when playing music?
Is the hum gone when you stop the motor?

/Hugo

Jan Dupont 4th June 2003 10:02 PM

I think that you must check the ground wire to the motor... There must be a bad connection there.......:scratch:

Delboy 5th June 2003 07:59 AM

Quote:

Originally posted by Netlist
Hi, Delboy

What brand is it?
Does the hum increase when you move the arm in the up-position towards the spindle, or only when playing music?
Is the hum gone when you stop the motor?

/Hugo


Hi Netlist,

The cartidge is the Music Maker and it only hums when the motor is spinning whether it is in the up or down position, as long as it is close to the spindle.

Delboy 5th June 2003 08:01 AM

Quote:

Originally posted by ACD
I think that you must check the ground wire to the motor... There must be a bad connection there.......:scratch:

Hi ACD,

There are 3 wires to the ac motor, I can't see which is the ground. How can I find out which wire it is?

Jan Dupont 6th June 2003 07:55 AM

Quote:

There are 3 wires to the ac motor, I can't see which is the ground.
It's hard to tell, as there are no standard colours for this.:scratch:
Try to see where they are comming from..
Otherwise take a simple wire and attach it to the ground pin of one of the signal phono plugs.
Then (with the motor running) shortly touch the other end of the wire to the metal housing of your arm (near the pick-up). If the hum disappear, your ground wire to the arm is bad.
If this is not the case, then shortly touch the free end of the wire to a metal part on your motor.

One of the above should solve the problem
Keep us informed about the results :up:

stefanobilliani 6th June 2003 08:29 AM

Quote:

Originally posted by ACD
One of the above should solve the problem


I encountred the same problem with an AC motor ,but a ground connection to metal parts of the motor didn't solve it .

It is a matter of cartridge . Not every cartridge rejects the noise from motor at the same way. Sometime , if the noise is very high is better use a low-voltage-electronically-controlled motor.

Generally high voltage AC motors are more intrusive , but I did not find the problem using MC phono cartridges.

Delboy 10th June 2003 11:02 PM

Quote:

Originally posted by ACD


It's hard to tell, as there are no standard colours for this.:scratch:
Try to see where they are comming from..
Otherwise take a simple wire and attach it to the ground pin of one of the signal phono plugs.
Then (with the motor running) shortly touch the other end of the wire to the metal housing of your arm (near the pick-up). If the hum disappear, your ground wire to the arm is bad.
If this is not the case, then shortly touch the free end of the wire to a metal part on your motor.

One of the above should solve the problem
Keep us informed about the results :up:


I have already tried these things to no avail, the hum is still present, but thanks for your input.

Quote:

Originally posted by stefanobilliani



I encountred the same problem with an AC motor ,but a ground connection to metal parts of the motor didn't solve it .

It is a matter of cartridge . Not every cartridge rejects the noise from motor at the same way. Sometime , if the noise is very high is better use a low-voltage-electronically-controlled motor.

Generally high voltage AC motors are more intrusive , but I did not find the problem using MC phono cartridges.


I think that this is most likely as you say an ac motor problem. I am looking into trying a dc motor with my tt to see if this cures the hum. Thanks for your contribution


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