Audio Technica pl120 turntable

Remove the 4 wires to the cartridge. With the system on. Put your finger on each of the wires separately. On two of the wires you should hear a buzz (one on each channel) on the others very little or perhaps a faint buzz.
If you hear the loud buzz(s) the amp inside the deck is working and you have either a faulty cartridge or have not connected the two wires right.
If you don't hear any buzz, the amp inside the unit is faulty. If the amp has other functions that do work (such as radio) then it is the pre-amp for the cartridge that has gone. As this will not affect the other functions.

What you need to do is disconect the turntable from the amp and touch the phono connectors of the amp. You should hear a buzz on each channel. If you don't then the pre-amp for the deck inside the amp is faulty. If OK plug the turntable back in to the amp and remove the connectors to the cartridge. With the amp on - touch each wire end cartridge connector. You should hear a buzz on the left with one wire and a buzz on the right with another wire. The other two wires are earth and will not probably give a responce. Again no buzz and there's a fault in the wires that connect to your amp. Or a fault inside the turntable itself.

Wrong power adapter most likely used and unit is damaged

Disconnect the wires from the cartridge. Then with the amp on touch each of the four wires with your finger. You should hear a loud buzz on two of the wires one on each channel. If you don't then the connections could be faulty. If you can hear the buzz, get someone else to move the wires connecting the deck to the unit. If you loose the buzz then something is poorly connected.
If all is good and the buzz is present no matter what you do, then either you have a bad connection to the cartridge or the cartridge is faulty.

see this causes and fix it. God bless you
Magnetron If the microwave is loud or noisy only when cooking, the magnetron tube might be defective. The magnetron uses high voltage, high current DC power to generate the microwave frequency that cooks the food. Under normal circumstances the magnetron is nearly silent. However if it is damaged or nearly burned out it can begin emitting high pitched or growling noises. It's not normally dangerous to use a microwave oven when it makes these noises, but they are an indication that the magnetron is almost dead and will need to be replaced.
Exhaust Fan Motor If the microwave is loud when running the fan motor might be
Stirrer Motor If the microwave is loud or noisy the stirrer motor might be worn out. The stirrer is a metal blade which slowly turns around, deflecting the microwave energy in a random pattern inside the microwave oven. As the motor nears the end of its useful life it begins to make grinding noises. The microwave will not heat food evenly without this stirrer, the motor should be replaced.
Turntable Motor If the microwave is loud or noisy the turntable motor might be worn out. This is a common problem and relatively easy to replace.

I'm thinking you have an open shield ground on the RCA input side. Connecting speaker inputs possibly restores the ground. Try connecting the high level inputs then disconnect the remote end of the cables (floating the grounds).

Then get out an ohmmeter and find that open circuitor or bad solder joint between RCA ground and real ground in the speaker's amplifier. Or.... if speaker ground kills the hum and you want to use RCA Line Level input to the sub, just connect one minus speaker output on your source amp to one minus on the sub's amp.

First you need to know if it's the turntable and not the amplifier or connections. Unplug the RCA Jacks right at the turntable. The male jack should be the one(s) going to the amplifier/receiver. Just holding your finger against the jack tip should give you a loud buzz out of your speakers. If not, the cabling, or more likely the switch selections on the amp are set improperly. It isn't likely at all that the cartridge is bad on both left and right channels. Check switch settings carefully.

Loud buzzing normally means dc on output or through your spaeker,amplifier needs to be serviced as it is faulty

You have a bad set of Audio output IC's for the sub. There is two of them. TDA7293 REPLACE BOTH!!!
There is 4 on one side of board,and 2 on other "also 1 small one" The the two are for the sub,the other 4 are for the main speakers/surround. They sell on Ebay for $6-10 each or a kit of all 6 for $25. I would replace all 6 on your system. To insure that the other's do not go bad after fixing the bad ones.

You maybe be able to turn the internal speakers off through the tv's menu...either in the Audio section or in Settings