I own an AU-517 sansui since 1979 but now im getting serious feedback from both phono inputs. what might be wrong and is it fixable

Help and a repair video in the link

https://www.google.com/search?q=Sansui+AU-G77X+Amplifier.+Protection+light+blinking

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But it's an antique :>D It is before the time of HDMI connectors and may well be before the time of composite audio. You would be looking to Phono Connectors 'Out' on the television and a Phono Input Source on the AVR 2000.

There is full specs and manuals here, but you have to register to get them.
https://www.hifiengine.com/manual_library/sansui/2000.shtml

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What's not working about them? The only thing that should be hooked up to a phono input is a non-amplified phonograph. Phono inputs usually have a preamp attached to them that will cause other signals to be over-driven and become distorted if they are used.

The Phono section has a very high level of amplification and so the audio input is very sensitive. So a possible faulty/loose grounding of the input can create a HUM which can be due to even a poor shielding of the input from stray AC factors. So you need to check for the these factors that can bring in the hum , you can confirm by isolating the phono circuit and working to the faulty stage.
Also it can be due to a faulty power supply - non filtering in DC- to the phono preamplifier.Finally faulty capacitors in power and feedback circuits can be a reason- check the negative feedback circuit which can be an op-amp with a feedback , check the capcitors here as a higher amplification can also be a reason.- check the preamp IC.

PHONO is ONLY for TURNTABLES. That's why they don't call it AUX.

Wired as I described in the other request, the EQ will have effect of anything that amplifier uses for input once you engage the tape loop the EQ is installed on.

Yup, get a PHONO preamp.

"PHONO" is the only designated connection on an audio device that is literal and exclusive. Nothing but PHONO will work right on it and old-school turntables would require it to preamplify the tiny current produced by a Phono cartridge.

If your unit doesn't have a PHONO connection you will have to get a Phono Preamp to connect between the TT and any Line Level input, like Aux.

eBay always has some... http://shop.ebay.com/?_from=R40&_trksid=p3984.m570.l1311&_nkw=phono+preamp&_sacat=See-All-Categories

I imagine everything is also VERY LOUD.

Only a Phono (old school turntable) should be plugged into the Phono inputs. It contains a preamp for the tiny signal provided by a Phono cartridge, plus is alters the frequency response drastically to compensate for the RIAA curve applied when they cut the record from tape.

The AT-PL120 uses a magnetic cartridge to extract a music signal from the record. Magnetic cartridges all put out a very weak electric signal, and so their output must be strengthened, or amplified, to where it is as strong as the input from, say, a CD player. This amplification is provided by a pre-amp. If your receiver has dedicated "phono" inputs the pre-amp circuits are already in the receiver. If you do not have dedicated phono inputs you must either buy a pre-amp, or buy a magnetic cartridge turntable with a pre-amp built into itself. The AT-PL120 has a built in pre-amp. You can switch the AT-PL120's preamp on or off. The switch is located under the platter at the back side of the turntable. Take the platter mat off and turn one of the platter's holes to the back and you should see the switch through the hole. If you push the switch to LINE OUT the preamp is turned on and the turntable sends an amplified cartridge signal out the cables which MUST be connected to a receiver inout suitable for a CD player (a "high level" input). If you push the pre-amp selector switch to PHONO OUT the turntable sends the weak unstrengthened cartridge signal out the cables which MUST be connected to the receiver's dedicated PHONO inputs so the signal can be amplified with the receiver's own pre-amp circuits.

If everything is set wrong (i.e. LINE OUT (pre-amp on), and connected to phono inputs) you are applying two steps of strengthening to the turntable's signal which is too much. The resultant sound will be garbled. Try not to do this!

The other way to do everything wrong is set the pre-amp switch to PHONO OUT (pre-amp off) and connect the turntable's cables to a high level input. If this happens the turntable signal receives no amplification and the resultant sound will be thin and weak.

Are you wanting to play he audio from your tv through you Sansui Stereo. If you have audio outs on you tv then connect them to the aux input of the receiver. If you ae using a cable box r sat reciever you can connect the audio out from these devices to the aux or any input other than phono input of your Sansui receiver.