feedback buzz in record mode on mpc 1000

hey everybody. just bought an mpc 1000 the other day after getting my tax returns back. i'm a totally new to music production and i have a lot to learn but i'm slowly getting the hang of things.
i've run into a slight problem when trying to record from my record player into my mpc 1000. there is an annoying feedback buzz when i'm in record mode for some reason. even when i'm not playing music through the mpc there is still an annoying buzz. i tried recording with the main volume all the way down and still, buzz.
what am i doing wrong?

your gain stageing is wrong
you propably have your recored knob all the way to the right
when recording a sample put the gain up on the turntable mixer or the source
and have the recored knob around halfway
after recording you can turn the knob all the way to the left to elminate the noise from the machine as your makin a beat

nah, when i recorded the record gain was exactly halfway. but the buzz gets louder the more the main volume and the record gain are turned up, of course. the thing is im not running my turntable through a mixer only a preamp so i cant **** with the gain on my source.

does the turntable need to be grounded?

yeah but its grounded. its grounded from my turntable and my preamp is grounded then its going out to my mpc 1000.
i just got home from work and tried tightening down my ground wires even more and still, fuzz buzz. buncha crap.