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Turntable hum

ZenithNut

ZenithNut

Member
So I got this pioneer pl 117D for free the other day and plan on replacing my sears roebuck lxi belt drive tt with it. I cleaned it up and tried hooking it up to my set up, which atm is a vector research vr 2000 fm/am receiver, a pair of 2nd gen realistic mach ones (with new foam surrounds), and a pair of early 60s made klh sixes. I have the turntable grounded out to the receiver and when I switch to phono it hums from the speakers horribly. If I move it away from the speakers it hums considerably less but still bad. I looked under the tt and checked everything, nothings disconnected, so its probably a signal interference. rather than a ground issue. Any input you guys could offer me would be really appreciated!
 
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Use your ohmmeter. This symptom is often caused by an open ground connection somewhere in the turntable or interconnects. The cartridge itself may be open-circuit, but don't put any current from the ohmmeter through the cartridge unless you rule out all other possibilities.
 
HUM…let me think.
Do you have your stereo gear near light switches with dimmers, ceiling fans, fans, refrigerators, microwaves, cell phone towers, televisions, antennas, etc? Is your air really dry? Are any wire types crossing other wires, such as the TT rca cables and the Vector's power cord or speaker wires?
 
BinaryMike said:
Use your ohmmeter. This symptom is often caused by an open ground connection somewhere in the turntable or interconnects. The cartridge itself may be open-circuit, but don't put any current from the ohmmeter through the cartridge unless you rule out all other possibilities.
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Actually the cartridge is bad and I have it removed. The head shell is on tight, and I just took it off and put it back on again. The rca cords arent intertangled, and itll hum if the tt is plugged in or out. There might be an open ground because itll quite down if I have my finger on the tone arm but still hum pretty bad at less than half volume.
 
is the ground wire attached to the ground terminal post and not the am/fm posts or case screws?

In any case, I'd use cheap speakers until the issue is solved. Mach 1 speakers are great. I have them too and the surrounds are still going strong for decades old.
 
need a cart. +1 above
-you may still have hum but the cart is out of the ='sion. might look into new cables, too. You can usually find some vid grade (low noise shielded) at GW for peanuts that easily adapt to a TT.
 
It had just as much hum when the cart was installed as well. Anyways if anyones familiar with this turntable, theres a little blue wire that grounds to a post on the silver side of the bottom lid. If i hold onto this post with the blue wire attachted thehu goes back to what would be considered "normal level'. I think if I attach another ground wire from this post to the reciever ground post itll go away. Hold on
 
OK So new rca cables might work. If i touch the rca jacks they hum increases dramatically, even though theyre coated in rubber.
 
No all the wires were soldered onto the terminal tree. Its all connected. I do have the SM.
But I think its weird that if i touch the exterior of the rca jacks the hum gets worse. Theres a blue wire that grounds to a post on the bottom cover, and if i touch it the hum goes all the way down.
 
ZenithNut said:
I have the turntable grounded out to the receiver and when I switch to phono it hums from the speakers horribly.
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Put the cart back on the table and disconnect the ground to the receiver and move it away from other wires. You don't have to use a tt ground wire, sometimes they create hum, sometimes they get rid of it, it's your choice as to what works best. Also don't have you IC all bunched up with other wiring.

Are you using a stand alone stage?
 
4-2-7 said:
Put the cart back on the table and disconnect the ground to the receiver and move it away from other wires. You don't have to use a tt ground wire, sometimes they create hum, sometimes they get rid of it, it's your choice as to what works best. Also don't have you IC all bunched up with other wiring.

Are you using a stand alone stage?
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The wiring is apart from each other, also the hum was worse with the ground disconnected. Theres a second ground that clips to a post on the tt bottom cover, it quites down if I touch said post.
 
ZenithNut said:
The wiring is apart from each other, also the hum was worse with the ground disconnected. Theres a second ground that clips to a post on the tt bottom cover, it quites down if I touch said post.
Click to expand...

So you didn't put the cartridge back on like I ask?
If you didn't disregard below, if you did follow the below. We can't help if you don't test as we ask.
The ground, (little blue wire) will be the tonearm ground, so it's sounding like the issue might be in the arm.

With the cart on the table and all set up correctly, volume set at normal listening levels. start the tt with a record on it, cue down at the start of the record, cue down at the end of the record moving your hands away both times.

Is the hum louder at the beginning of the record or at the end?
 
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