How do I stop the Humming from my LP12?

Hi all this is my first turntable. I am new at this. I have two problems. I purchased a used Linn LP12 circa 1974 with the original power supply, Infinity Black Widow tonearm, AT - 30 Moving coil Cart, AT step-up transformer, Creek 5350 Integrated with built in MM phono amp, Vandersteen 2ce speakers. The cartridge came premounted by Brooklyn Audio. When I play a record, the music sounds good, but when there is no record playing there is an audible hum coming from the speakers that gets louder as increase the volume level. When the Amp is in any other mode like CD or Aux, there is no humming noise. Any thoughts as to what this is and how to eliminate it? My second problem is that with the table set up according the instructions I can hear the belt rubbing against the top of the guide that it threads through when it is spinning. Even when I try to adjust the belt to the bottom of the subplatter disc, and then replace the platter, the rubbing continues. Any suggestions would be appreciated. Thanks - Dave
On the hum issue, check all connections (including the four tiny connectors at the cart). Since you have a transformer, make sure the cable running to and from it is a shielded type. Make sure no phono cable is near an AC line. It may be a malfunction somewhere or it may simply be that you are not used to having any level of noise of the type you find with a turntable in the system. Whatever noise emanates from the tt/arm/cart/transformer and their cabling should be very little though. Putting your volume control at its highest is not a very good test since any noise will be amplified significantly. It all depends on how much noise you actually have.

The other issue is purely mechanical and probably has to do with the fact the Linn has a suspended chassis that might need some fine tuning. Cleaning the belt and putting talcum on it wouldn't hurt either, but I doubt it would cure your problem for any appreciable period.

Good luck. Oh, and don't believe folks who tell you that LP analog is the be all and end all. It might have a certain quality of sound that makes it very attractive, but it has drawbacks that devotees tend to be mum about at best or flatly deny at worst.

Good luck.
Did you connect the ground wire?
Thanks for the suggestions. Yes the ground wire is connected. I will double check the other connections and report back. Thanks for the intitial advice. This is a great community. Best regards, Dave
Teach it the words!!!
I've gone through a process of upgrading my TT's over the last 2 years, and seemingly every time I make an adjustment or swapped equipment (ie Tables, Arms, Cart's, Pre's) had similar issues surface. Here's some of the problems I've encountered:

first the easy problems that can be solved with repositioning and or cleaning connections -
1) Poor interconnect cable connection between preamp and phono pre. Poor ground connection - on preamp, on table, or on the arm.
2) poor cartridge lead connection (between cart and arm)
3) Table in too close proximity to preamp. Be careful not to position your preamp close to and directly above or below your table.

Now the harder problems -
4) bad ground post on my preamp (yes, the assembly at the factory was incorrect).
5) Bad Cartridge - I had to send it back for warranty service on a ground connection.
6) 60hz feedback from motor to cartridge - some cart's are susceptible to this. My Grado Sonata just did not like being mounted on my Heybrook TT2. The closer the cart got to the center spindle (and the motor), the louder the hum got. This is a problem only with 120V motors. 12VDC motors shouldn't be a problem.
7) Bad wiring inside the tonearm (this is a problem with buying a used tonearm) - had to be re-wired.

I also found that some cartridges are much harder to get quieted down, while others are easy. And finally, as Pbb indicates, expect more noise than you're use to with cd player.