Ibanez CS5 insufferable whistling noise, how do I fix this?

[logimite]

Hi guys! first post here, longtime no account lurker. Anyways, I got an ibanez cs5 and it had a *really* bad whistling noise that drives me crazy every time I turn on my amp. Any way to modify the circuit to get rid of it? My trex diva drive is on the same psu and doesn't make the sound. Also the sound remains when it is off too.

[logimite]

example of the whistle: https://www.sndup.net/fr5h/

[Rob Strand]

Are you powering it from a switch-mode power supply?

Try a battery and see if it stops.

Another thing  to try is to put a dummy load resistor on the power supply, say 100 ohm (1W) or 220 ohm (1/2 W).