I have Pioneer PL-990 turntable and it's experiencing a small buzzing sound. I've got it plugged in via AUX to a Sherwood receiver (the turntable has a preamp), which has Sony speakers plugged into it as well. These are the only two things plugged into the receiver.
When I unplug the turntable from the receiver or switch channels, the buzzing goes away, but otherwise it's constant. It's hard to hear unless I'm right next the speaker, but just the fact that it's there makes me worry. The receiver and turntable are both plugged into the same power strip, and as far as I know I shouldn't need to ground the turntable, but I'm not ruling that out as the problem. There isn't any area on the turntable to plug in a grounding wire.
I'm not very advanced in this area, so can anyone offer me any advice to get rid of the buzz?
First, you shouldn't plug the turntable into the "aux" input. It needs to go into the "phono" input.
Oxidized connections can cause a grounding issue that would result in noise. However, virtually any table requires a ground from the tonearm to the phono pre amp. This is typically (and certainly on a Pioneer) a thin cable (wire) that runs from the bottom of the table's base and needs to be connected to a ground lug on the receiver. This ground cable can be either a separate wire or a wire that is moulded into the phono leads and is terminated with either a bare wire connection or a spade lug.
The instructions say to plug it into the auxiliary input instead of phono, because of the preamp on the turntable. When I plug it into phono there is a very loud buzzing.
So I need to open up the turntable and connect a ground wire in there somewhere to the receiver?
Sorry, no. I misread your statement about the pre amp. With the phono pre amp in the table there should be no need for a ground between the table and the receiver.
That does not mean a ground strap will not solve your problem. Try connecting a cable to the turntable and touching the other end to the ground lug of the receiver. Without seeing the two items it's difficult to tell you where to make your connections.
Do you have a VOM (a meter) to check continuity? If so, you need to find a screw on the table that has continuity with the ground ring (outer portion) of the RCA's (connectors) that feed your signal out of the table. Find a similar screw on the receiver - one that has continuity with the ground side of the RCA inputs. Be careful making your connection because a screw can be insulated by paint from the actual chassis ground. If you don't solve your problem by touching one screw, try another. Usually the screws that hold the feet on a receiver chassis will be a ground point. Do this with the volume lowered.
If grounding the table to the receiver doesn't help, try running your ground cable from the table to the center screw on your AC outlet.
If this doesn't solve your problem, then we'll move on to the next most likely thing to try.