If the reverb is set above 1 or 2 there's a siren like noise and this noise gets louder as i turn up the reverb if you unplug the red and white Rca plugs from the reveb tank the sound goes away and the amp works fine but then i have no reverb what is wrong with my reverb tank?

Music - Fender - Frontman 212R 100W 2x12 Guitar Combo Amplifier