Phaser like effect when recording with Tascam DR-40

[Gronlund]

I have been noticing an undesired cycling type of effect on recordings lately when using the built in condenser mics on my DR-40. It comes and goes. I bought the unit about a year ago. It's in great shape and I have taken care of it well. I don't know what to make of this odd noise. It slowly cycles up and down somewhat like a phaser or flanger effect and adds or cuts treble or low end kind of like a wah pedal very slowly being lowered and raised. Hard to explain but very odd and incredibly annoying. Anyone else experience this or know what to make of it?

 

[dthem51]

My DR-05 is doing the exact same thing...kind of a swirling phaser effect whether recording live or with mini-jack from my digital piano!!