It looks like it has a phono input, but NOT the internal phono pre-amp & RIAA stage. In the manual’s troubleshooting: “If your turntable doesn’t have a built-in phono preamp, you must connect one between it and the AV receiver/AV amplifier. If your turntable uses an MC cartridge, you must connect an MC head amp, or an MC transformer and phono equalizer.”
The manual: https://www.intl.onkyo.com/downloads/manuals/pdf/tx-sr705_manual_e.pdf
After turntables dropped in sales in the early 1990s, many companies stop putting phono pre-amps in receivers to save money & because they also sold turntables that had their own built-in phono pre-amps. The SR-FX70 is from the 80s & would not have one.