Hum

Hi,

I am having a new problem with my Technics SP15 - AT ATP-12T set up.

It has developed an acute hum. Both ground cables - turntable and tonearm - are properly connected to the preamp's ground. There are no shorts, continuity is fine. CD no problem.

The preamp's PS and the power amp are far away from the Technics. I really do not know what else to check.

Please advise.

Many thanks.

Horacio
 
I neither have shorting plugs nor resistors to build a pair. Instead, I connected the record player to an integrated amplifier. The hum is still there. It is the same with either a MC or a MM cartridge.

I built the plinth a few years ago, installed the deck and arm and it worked fine.

Cheers,
 
Hi,

I am having a new problem with my Technics SP15 - AT ATP-12T set up.

It has developed an acute hum. Both ground cables - turntable and tonearm - are properly connected to the preamp's ground. There are no shorts, continuity is fine. CD no problem.

The preamp's PS and the power amp are far away from the Technics. I really do not know what else to check.

Please advise.

Many thanks.

Horacio
If you have not tried it yet, wrap the ground wire around the two cables tightly the entire way.

jn
 
No, I did not. Then, I just removed the tonearm and table from the plinth, checked everything and put it all back together. I also replaced the interconnects but it is the same.
 

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Ok.

If you accidentally swap the grounds to the cartridge you will also get very bad hum. It will all measure ok on your meter, but terrible hum. Quick check for this problem is if you move the interconnect around the hum changes, or if you bunch it it will also change in level.

I swapped a cartridge out and put the ground connectors around the wrong way - hunted for that one for hours :D
 
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When you say you replaced the interconnects, is the interconnect straight plug to plug each end? O4 is it captive at the T/T end and you had to solder it in the T/T?

If plug to plug, have you tried another cable?

Also, make sure on the head shell connector receptacle side (ie the arm side) that the grounds are not accidentally touching - this can also cause a problem.