The previous posting is correct, turntables usually have ground wires that need to be connected to the amplifier or receiver chassis. Usually there is a ground screw attachment point on the back of the amplifier or receiver. When you have done that, then check the following:
On older audio gear, the power plugs are not polarized. It can make a noticable difference which way you have the plug in the outlet.
First determine the best orientation for the Luxman receiver plug by turning up the volume with no input on one of the high level inputs such as tape, then do the same with the input selected for phono. If you turn the volume way up with no input, you will probably hear some slight high frequency hissing, but also any AC line hum that is present. Note how high the volume is set when the hum becomes audible.
Next, turn down the volume, power off the unit and unplug it from the outlet and then flip the plug over and reinsert. Power up and again raise the volume to see if the hum is greater than before or is diminished at the same volume control setting.
When you have the plug oriented in the socket with the least audible hum, mark the plug so you know which is the hot and which is the neutral plug tip. The hot tip will be the one in the smaller of the two plug socket openings. Then, repeat this procedure for the turntable.
Getting the polarity of the plugs right can make a big difference in eliminating any hum you may hear.
If you after you try these remedies and you still have noticable hum coming from the Luxman, on low level (phono) as well as the high level inputs such as tape or auxilliary, your amplifier may have one or more leaky capacitors (electrically leaking not actually dripping some noxious liquid) in the power supply. This is a common problem in older gear and can be repaired.